Lower Carboniferous clastic sedimentary rocks(i.e.,the Nanduan Formation)in the Changning-Menglian belt of the southeastern Tibetan Plateau may provide new insights into the tectonic evolution of the Paleo-Tethys Ocea...Lower Carboniferous clastic sedimentary rocks(i.e.,the Nanduan Formation)in the Changning-Menglian belt of the southeastern Tibetan Plateau may provide new insights into the tectonic evolution of the Paleo-Tethys Ocean.This paper presents new petrographic,geochemical,and detrital zircon U-Pb age data to constrain the provenance and depositional setting of these rocks.Sandstone samples of the Nanduan Formation are all quartz arenites(Q_(92-99)F_(1-7)L_(0-2))with high SiO_(2)contents(85.1 wt.%-95.2 wt.%;average=90.9 wt.%),indicating high compositional maturity.They exhibit fractionated rare earth element(REE)patterns,with light REE enrichment[(La/Yb)_(N)=6.48-12.1]and negative Eu anomalies(Eu/Eu^(*)=0.53-0.74),and marked negative Sr-Cs-V-Cr-Ni anomalies in upper continental crust-normalised multi-element diagrams.The geochemical features and heavy mineral assemblages suggest that sediments were mainly derived from ancient sedimentary rocks in cratonic interiors or stable continental areas,and were probably deposited in a passive continental margin setting.Detrital zircon U-Pb dating(n=256)of the Nanduan Formation sandstones defines three distinct age peaks in the Pan-African(600-500 Ma),younger Grenvillian(950-850 Ma),and older Grenvillian(1250-1000 Ma).Their zircon age spectra are similar to those of Lower Paleozoic sedimentary rocks(i.e.,the Mengtong and Mengdingjie groups)in the BaoshanSibumasu Block,but significantly different from those of older rocks in the Simao-Indochina and other surrounding blocks(i.e.,the western Yangtze,western Cathaysia,western Qiangtang,Tethyan Himalaya,and Lhasa blocks).This suggests that the Nanduan Formation was deposited at the margin of the Baoshan-Sibumasu Block.Combining the new data presented in this study with published data,we suggest that the Nanduan Formation and underlying Lancang Group were deposited in the same setting during the Early and Late Paleozoic,respectively.展开更多
The giant Jiama deposit is a post-collisional porphyry Cu-polymetallic system located in the Gangdese metallogenic belt of Xizang.It consists of three deposits:The Main deposit,the Zegulangbei deposit,and the South Pi...The giant Jiama deposit is a post-collisional porphyry Cu-polymetallic system located in the Gangdese metallogenic belt of Xizang.It consists of three deposits:The Main deposit,the Zegulangbei deposit,and the South Pit deposit according to exploration and research.The South Pit deposit is a high-grade Cu-Pb-Zn deposit,but its genesis is unclear.To investigate its genesis,a detailed study was conducted on the deposit geology,geochronology and amphibole geochemistry.The results indicate that the weighted average 206Pb/238U age of the zircons from the granite porphyry in the South Pit is 15.38±0.45 Ma,and the molybdenite from the mineralized skarn yield a ReOs isochron age of 15.23±0.22 Ma,in line with the age of the Main deposit(15.7-14.3 Ma).The amphiboles in the granite porphyry of the South Pit,magnesiohornblende and actinolite,are high in Mg and Ca and low in K.They crystallized at temperatures of 705-7490C,pressures of 0.44-0.67 kbar,oxygen fugacity of-14.31--13.69(NNO),and depths of 1.7-2.5 km.Mapping of structure and alteration indicates that the South Pit skarn developed due to the metasomatism of marble of hornfels or carbonate in fold hinge dilation and an interlayer detachment zone by magmatic hydrothermal fluids.According to the age of magmatism and geological features,the South Pit deposit and the Main deposit have originated from the same Miocene magmatism,but the South Pit deposit was affected by the gliding nappe tectonic system.The amphibole geochemistry indicates that the ore-related magma of the South Pit has a high oxygen fugacity and is rich in water.展开更多
The Suzhou granitic pluton is the first identified Nb-Ta-rich granite in China.To reveal the genetic link between the sequence of magmatic and hydrothermal evolution and Nb-Ta mineralization in different intrusive pha...The Suzhou granitic pluton is the first identified Nb-Ta-rich granite in China.To reveal the genetic link between the sequence of magmatic and hydrothermal evolution and Nb-Ta mineralization in different intrusive phases of the Suzhou granite,whole-rock geochemistry,geochemistry and U-Th-Pb dating of monazite was analyzed.The unique geochemical characteristics show that the Suzhou pluton can be discriminated as an A-type granite.LA-ICP-MS U-Th-Pb dating of monazite in both the medium-and coarse-grained biotite granite(MBG)and the fine-grained biotite granite(FBG)indicates that the granite formed between 124 and 127 Ma.Based on geochemical characteristics and mineral textures,the MBG(Mnz-Ia)and FBG(Mnz-Ib)monazites are classified as magmatic monazites;another monazite(Mnz-II)from the MBG formed during a magmatic-hydrothermal transitional stage.Nb-Ta in the Suzhou pluton gradually concentrated during fractional crystallization and alteration of Ti-rich minerals and biotite.Ultimately,with the involvement of F-Li-rich fluid,Nb-Ta mineralization occurred during the magmatic-hydrothermal transition.The Suzhou pluton is considered part of a 600-km-and NE-SW-trending Nb-rich A-type granite belt together with other Early Cretaceous A-type granites in the Jiangnan Orogen that offers prospects of a new target for Nb-Ta prospecting.展开更多
Detrital zircon geochronology is reported from the c.1200 m thick Cambro-Ordovician sedimentary succession recovered in core from the COSC-2 continental drilling project in the Scandinavian Caledonides.Above a regolit...Detrital zircon geochronology is reported from the c.1200 m thick Cambro-Ordovician sedimentary succession recovered in core from the COSC-2 continental drilling project in the Scandinavian Caledonides.Above a regolith marking the sub-Cambrian peneplain,a lower to middle Cambrian(?)succession comprises conglomerate,sandstone and shale overlain by gravity flows fining upwards into the Alum Shale Formation.First results of detrital zircon geochronology from the Cambrian(?)succession show that the basal section of the autochthonous cover is characterized by mainly late Paleoproterozoic–early Mesoproterozoic detrital grains.The middle part of the succession is dominated by late Paleoproterozoic detritus with minor Mesoproterozoic and Archean input.The upper part of lower Cambrian(?)succession is characterized by Archean to Cambrian detritus.The maximum depositional age is calculated to 530.5±4 Ma for the upper part of the lower Cambrian succession.Two samples from the Lower Ordovician(?)succession above the Alum Shale Formation show predominantly Mesoproterozoic to early Neoproterozoic(1.5–0.9 Ga)ages.The autochthonous lower Cambrian(?)passive margin succession in the lower section is dominated by local detritus,sourced exclusively from the Eastern Segment of the Sveconorwegian Orogen,which includes the basement studied in COSC-2.Up-section,the provenance shifts towards the Transscandinavian Igneous Belt and Svecofennian Orogen sources,with the youngest part of the succession showing a notable input of Neoproterozoic–Cambrian active margin detritus.The Ordovician(?)succession is characterized by populations,likely derived from the Sveconorwegian Orogen,and a minor cratonic contribution.Statistical analysis of detrital zircon datasets across Baltica suggests that the Southern Baltica/Sandomirian Arc,rather than the Timanian Orogen,was a significant source of detrital material across the paleocontinent.The influence of Timanian Orogen grains is limited to northernmost Scandinavia,whereas Sandomirian detritus reached central Scandinavia in the lower to middle Cambrian and remained prevalent in southern Scandinavia into the Lower Ordovician.展开更多
We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and g...We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and geochemical data,the granitoids in the region can be divided into two age groups:ca.285 Ma and ca.269 Ma.The granitoids of the first group are mainly composed of calc-alkaline to high-K calc-alkaline,weakly peraluminous Ⅰ-type granodiorites with ε_(Hf)(t)values of-19.6 to-4.3,which demonstrates evidence of crustal reworking;the granitoids of the second group,however,mainly consist of A-type granites that are high-K calc-alkaline to shoshonite,metaluminous to weakly peraluminous,and have high 10,000×Ga/Al ratios(2.59-3.12)and ε_(Hf)(t)values ranging from-11.3 to-2.7,all of which demonstrates a mixed crust-mantle source.We interpret the granitoids of the first group to have formed during the subduction of Central Asian oceanic crust and the second group to have formed by the asthenospheric upwelling caused by the formation of slab windows during late ocean ridge subduction.展开更多
The Southern Granulite Terrane(Dharwar Craton),South India,is a key unit for understanding the origin of charnockite.New U-Pb and Lu-Hf analyses in zircon crys-tals from 16 samples representing a wide variety of litho...The Southern Granulite Terrane(Dharwar Craton),South India,is a key unit for understanding the origin of charnockite.New U-Pb and Lu-Hf analyses in zircon crys-tals from 16 samples representing a wide variety of litho-types from the quarries in Kabbaldurga reveal a complex geological history in the Archean and early Paleoprotero-zoic.Magmatic protoliths predominantly record Paleoar-chean ages between 3.4 and 3.2 Ga.Combined U-Pb and Lu-Hf signatures indicate a history of recurrent crustal anatexis,juvenile magmatic input,and felsic injections.Mesoarchaean magmatic charnockites were generated mainly from hornblende-dehydration melting of Paleoar-chaean mafic rocks.In addition,Peninsular Gneissic Com-plex of the Dharwar Craton,commonly described as TTG suites,are likely generated by melting of hydrated basalt.The new data are consistent with the idea of a convecting magmatic cycle and also support the proposal that the southern Dharwar Craton comprises a tilted cross-sec-tion through the Archaean crust.Paleoproterozoic high-temperature event is documented here as a complex unit involving juvenile mafic magmatism,granulite facies imprints and crustal anatexis as well as felsic injections,occurring within a short time period around 2.5 Ga.展开更多
1.Objective The Eastern Junggar Kalamaili region in Xinjiang constitutes a significant tin metallogenic belt in northwest China(Fig.1a).It hosts four independent tin deposits-Kamusite,Ganliangzi,Beilekuduke,and Saresh...1.Objective The Eastern Junggar Kalamaili region in Xinjiang constitutes a significant tin metallogenic belt in northwest China(Fig.1a).It hosts four independent tin deposits-Kamusite,Ganliangzi,Beilekuduke,and Sareshenke-from west to east,supplemented by two tin mineralized points,namely Hongtujingzi and Sujiquan(Figs.1b).according to the ore type and the composition of gangue minerals,the tin deposits in the region are classified into two groups:Quartz vein type and greisen type,with the Sareshenke deposit ascribed to the former and the remainder to the latter.展开更多
To determine the geological age,petrogenesis,and tectonic setting of Mesozoic volcanic rocks in the Ningyuancun Formation in Xunke area,Lesser Hinggan Range,the zircon U-Pb geochronology,petrographic observations,and ...To determine the geological age,petrogenesis,and tectonic setting of Mesozoic volcanic rocks in the Ningyuancun Formation in Xunke area,Lesser Hinggan Range,the zircon U-Pb geochronology,petrographic observations,and geochemical analyses of major and trace elements were conducted in this study.Zircon U-Pb dating showed that the volcanic rocks of the Ningyuancun Formation were formed in the Early Cretaceous(112.97±0.90 Ma).Major element analyses revealed that the content of SiO_(2)weighted from 74.14%to 76.54%,indicating the volcanic rocks to be high-silica and felsic.The content of Al_(2)O_(3)varies from 12.48%to 13.65%.A total alkali content of the volcanic rocks range between 8.46%and 9.56%,with Na_(2)O/K_(2)O ratios from 0.69 to 0.89.This indicated that the volcanic rocks belonged to a highly differentiated calc-alkaline series.Additionally,A/CNK values range from 0.950 to 1.015,and A/NK values vary between 0.999 and 1.127,suggesting a peraluminous characteristic.Trace element analysis showed a right-sloping“V-shaped”REE pattern,with the enrichment in light REEs and a prominent negative anomaly of Eu.The volcanic rocks are enriched in Rb,Th,U,La,and Ce,while Ba,Sr,and Ti are depleted.Rb/Sr ratio ranges from 10.01 to 12.46,Ti/Y ratio is from 51.14 to 95.72,and Ti/Zr ratio is from 5.78 to 6.41.It is suggested that the magma was derived from the partial melting of crustal rocks.This evidenced that the Early Cretaceous high-silica rhyolites were formed in an intracontinental extension in eastern Northeast China during the northwestward subduction of the Pacific Plate.The crustal extension,asthenospheric mantle upwelling and underplating of mantle-derived magmas resulted in the residual crystalline mush in Early Cretaceous mafic magma chambers to erupt.展开更多
During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific subducti...During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific subduction.However,controversy exists about the Paleo-Pacific subduction's initiation time.This study uses detrital zircon U-Pb ages to discuss the Late Triassic source-tosink system in the SESCB.It provides some references for the Paleo-Pacific subduction process based on crucial age information and zircons'trace elements.The paleogeography and similarity of detrital zircon age distribution indicate that three sinks were found in the SESCB during the Late Triassic:1.the Yangchun-Kaiping-Gaoming area,comprising major age ranges of 260-220,460-400,and 1200-800 Ma,which might be sourced from the Yunkai terrane;2.the Jiexi-Kanshi-Nanjing area,characterized by the significant age component of 2000-1800 Ma,which corresponded to the Wuyi terrane;3.the Xinan area,consisting of significant age groups of 290-250 and 380-320 Ma,which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific subduction.Note that 290-250 Ma zircons were widely distributed in the Upper Triassic strata,and their trace elements suggested the existence of a magmatic arc near the SESCB during the 290-250 Ma.Thus,we propose that the Paleo-Pacific subduction might have begun in the Early Permian.展开更多
The Weining Beishan area of Ningxia Hui Autonomous Region is located at on the western edge of the Helanshan tectonic belt,which is a tectonic joint among Alxa Block,Ordos Block,and North Qilian orogenic belt.However,...The Weining Beishan area of Ningxia Hui Autonomous Region is located at on the western edge of the Helanshan tectonic belt,which is a tectonic joint among Alxa Block,Ordos Block,and North Qilian orogenic belt.However,the tectonic evolution of this area remains unclear due to the lack of magmatic information.This paper conducted researches on geochronology,geochemistry,and Sr-Nd-Hf isotopes of the diorite porphyrites exposed in the Weining Beishan area.The zircon U-Pb dating yields two ages of 145.0±1.1 and 146.2±1.5 Ma,and the whole-rock geochemical data indicate that the diorite porphyrites are metaluminous to weakly peraluminous and high-K calc-alkaline series.The characteristics of highly initial^(87)Sr/^(86)Sr ratios(0.70816 to 0.71047),negativeε_(Nd)(t)(−8.9 to−8.4),and negativeε_(Hf)(t)(−13.8 to−21.2)indicate that the diorite porphyrites originated from partial melting of the middle-lower ancient crust related to the North China Craton.Combined with the regional geology,we suggested that partial melting was triggered by a tectonic activity of deep faults cutting through the crust under the regional stress transformation from compressing to extension during the Late Jurassic–Early Cretaceous,which is probably related to the westward subduction of the Paleo-Pacific Plate.展开更多
Some of the earliest bio-sedimentary records of life on Earth are represented by microbial carbonates,which are also critical geochemical archives of ancient seawater chemistry and the environmental circumstances in w...Some of the earliest bio-sedimentary records of life on Earth are represented by microbial carbonates,which are also critical geochemical archives of ancient seawater chemistry and the environmental circumstances in which they precipitated.Reconstructing paleo-microbial environments on Earth and potentially other planets requires precise determination of the depositional ages of these materials.The(abiogenic)carbonate geochemistry communities can now use developments in in-situ laser ablation U-Pb dating using inductively coupled plasma mass spectrometry(LA-ICP-MS).Due to the effects of impurity mixing and diagenesis,microbial carbonates have received little geochronological study despite their broad relevance for understanding ancient seawater’s environmental conditions and geochemical compositions.This study demonstrates using time-of-flight mass spectrometry(TOF-MS)to perform quick,quantitative elemental mapping before U-Pb spot dating to improve experiment success rates and data reliability and offers four practical application examples.展开更多
The Triassic was a crucial period in the tectonic evolution of the South China Block.Research on tectonic deformation during this period provides information on intracontinental orogenic mechanisms in South China.In t...The Triassic was a crucial period in the tectonic evolution of the South China Block.Research on tectonic deformation during this period provides information on intracontinental orogenic mechanisms in South China.In this study,alongside thermochronological analyses,we examine the macroscopic and microscopic structural features of the Rongxian ductile shear zone,located south of the Darongshan granite in the southeastern part of Guangxi Province,on the southern margin of South China.Sinistral shear is indicated by the characteristics of rotatedσ-type feldspar porphyroclasts,stretching lineations defined by elongated quartz grains and the orientations of quartz c-axes.LA-ICP-MS U-Pb dating of zircons from two samples of granitic mylonite and one of granite yielded ages of ca.256 Ma.Furthermore,two samples of granitic mylonite yield muscovite^(40)Ar/^(39)Ar plateau ages of 249-246 Ma.These results indicate that the Rongxian ductile shear zone resulted from Early Triassic deformation of the late Permian Darongshan granite.This deformation was likely related to the closure of the eastern Paleo-Tethys Ocean and the subsequent collision of the South China and Indochina blocks,during the early stage of the Indosinian orogeny.展开更多
The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ag...The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ages of~101 and~98 Ma,and they have a high formation temperature(~910℃)and low oxygen fugacity value,indicating crystallization condition at low pressure in the upper crust with temperature of 678℃.The Qishan and Kuiqi miarolites are characterized by enrichment in SiO_(2) and high-K alkali,depletion in Ca and Mg,and belong to the high-K weak peraluminous rock series.The samples are enriched in HFSEs(i.e.,Ta,Zr and Hf)and LILEs(i.e.,Ba,P and Sr),depleted in Ba and Sr with the negative anomaly of Eu.In the primitive mantle normalized trace element spider diagram,the samples show a right-inclined‘seagull-type’pattern,combined the ratios of(La/Yb)_(N),10000×Al/Ga,Rb/Nb and Nb/Ta etc.,they were proved to be alkaline A-type granite.Combined the characterize of the trace elements,they were derived from clay-rich source accompanied pelite melting,and subjected to K-feldspar crystallization fractional.The values of ε_(Hf)(t)and tDM2 are distributed in the range of-2.8 to 3.3 with~1.2 Ga,and-6.0 to 4.0 with~1.2 Ga,revealing that they were generated from the Mesoproterozoic Cathaysia basement rocks.The comprehensive research reveals the Kuiqi and Qishan intrusions derived from crust-mantle mixing and partial melting of the crust,respectively,resulting from lithospheric extension generated by the Paleo-Pacific Plate subducted into the European-Asian Plate.展开更多
Geochemistry, zircon U–Pb geochronology, and Hf isotope data for the Early Paleozoic granites in the Baoshan Block reveal the Early Paleozoic tectonic evolution of the Proto-Tethys. The samples are high-K, calcalkali...Geochemistry, zircon U–Pb geochronology, and Hf isotope data for the Early Paleozoic granites in the Baoshan Block reveal the Early Paleozoic tectonic evolution of the Proto-Tethys. The samples are high-K, calcalkaline, strongly peraluminous rocks with A/CNK values of 1.37–1.46, are enriched in SiO2, K2O, and Rb, and are depleted in Nb, P, Ti, Eu, and heavy rare earth elements,which indicates the crystallization fractionation of the granitic magma. Zircon U–Pb dating indicates that they formed in ca. 480 Ma. The Nansa granites have εHf(t) values ranging from-16.04 to 4.36 with corresponding TC DMages of 2.10–0.81 Ga, which suggests the magmas derived from the partial melting of ancient metasedimentary with minor involvement of mantle-derived components. A synthesis of data for the Early Paleozoic igneous rocks in the Baoshan block and adjacent(Tengchong,Qiangtang, Sibumasu, Himalaya, etc.) blocks indicates that these blocks were all aligned along the proto-Tethyan margin of East Gondwana in the Early Paleozoic. The Early Paleozoic S-type granites from Nansa were generated in a high-temperature and low-pressure(HTLP) extensional tectonic setting, which resulted from Andean-type orogeny instead of the final assembly of Gondwana or crustal extension in a non-arc environment. In certain places, an expanding environment may exist in opposition to the tectonic backdrop of the lithosphere’s thickening and shortening, leading the crust to melt and decompress,mantle-derived materials to mix, and a small quantity of peraluminous granite to emerge.展开更多
In situ zircon U-Pb geochronological and Lu-Hf isotope studies of detrital zircons from Late Mesoproterozoic to Early Neoproterozoic sedimentary units on the southwestern margin of the Yangtze Block have important imp...In situ zircon U-Pb geochronological and Lu-Hf isotope studies of detrital zircons from Late Mesoproterozoic to Early Neoproterozoic sedimentary units on the southwestern margin of the Yangtze Block have important implications for the tectonic evolution of the Yangtze Block.The Huili Group contains zircons whose ages are mainly Late Archean to Mesoproterozoic(2650-2450,2100-1800,and 1350-1150 Ma).The Dengxiangying Group has one major age population of 1900-1600 Ma,and two subordinate age populations of 1350-1100 and 2300-2000 Ma.Yanbian Group sedimentary rocks have a zircon age population mainly in the range of 970-850 Ma,contemporaneous with the ages of widespread arc-related magmatism in the western Yangtze Block.Combining these results with previous work,the Huili and Dengxiangying groups were most likely deposited during ca.1160 to 1000 Ma in an intra-continental rift basin setting,while the Yanbian Group accumulated during>920 to 782 Ma in a back-arc basin setting at the southwestern margin of the Yangtze Block.In addition,all these results further suggest a tectonic transition from a continental rift basin to a convergent environment at the southwestern margin of the Yangtze Block at 1000-970 Ma.展开更多
Detrital U-bearing minerals(e.g.,zircon,apatite)U-Pb ages with specific trace-element geochemistry,are frequently used in provenance analyses.In this study,we focus on the Yarlung River drainage in South Xizang,charac...Detrital U-bearing minerals(e.g.,zircon,apatite)U-Pb ages with specific trace-element geochemistry,are frequently used in provenance analyses.In this study,we focus on the Yarlung River drainage in South Xizang,characterized by two distinct lithologic units:The Gangdese batholith to the north(mainly granitoids)and the Tethyan Himalaya(mainly sedimentary rocks)to the south,which plays a crucial role in the erosion of the Tibetan Plateau.To constrain the provenance of the Yarlung River Basin,we performed trace-element and U-Pb age analyses of detrital apatite from the river sands of the Yarlung River and its tributaries.Our findings indicate that the detrital apatite U-Pb age patterns of the north tributaries exhibit main peaks at approximately 40 and 60 Ma,consistent with the corresponding U-Pb age patterns of detrital zircon published.Further,their trace element casts fall mainly in the Type I granite region,also indicating the Gangdese arc-dominated source.However,those of the south tributaries(∼60–20 Ma)exhibit a different age distribution from the detrital zircon U-Pb groups(∼110–150,∼500,and 1100 Ma),suggesting that the detailed apatite U-Pb signals can provide excellent constraints on the provenance of igneous and metamorphic rock sources but less so for sedimentary rock sources.Combined with previous detrital zircon data in the study area,our detrital apatite information can highlight young metamorphic events from a complex background(i.e.,Niyang and Nianchu rivers),which offers additional constraints on the provenance of the Yarlung River Basin.Generally,a combination of geochemistry and geochronology of multi-detrital heavy minerals,such as zircon and apatite,can provide powerful tools for provenance analysis.展开更多
The development of laser ablation inductively coupled plasma quadrupole tandem mass spectrometry(LA-ICP-Q-MS/MS)opens new opportunities to rapidly date a variety of hydrothermal minerals.Here we present in situ Lu-Hf ...The development of laser ablation inductively coupled plasma quadrupole tandem mass spectrometry(LA-ICP-Q-MS/MS)opens new opportunities to rapidly date a variety of hydrothermal minerals.Here we present in situ Lu-Hf and Re-Os dates for hydrothermal apatite and molybdenite,respectively.We further report the first in situ Lu-Hf dates for bastnäsite,dolomite,and siderite,and assess their potential for constraining ore deposit geochronology.For method validation,we report isotope-dilution Lu-Hf dates for apatite reference material Bamble-1(1102±5 Ma)and calcite reference material ME-1(1531±7 Ma),enabling improved accuracy on matrix-matched calibration for LA-ICP-MS/MS Lu-Hf dating.The new methods are applied to the Vulcan Iron-Oxide Copper-Gold(IOCG)prospect in the Olympic Cu-Au Province of South Australia.Such deposits have been difficult to accurately date,given the general lack of reliable mineral geochronometers that are cogenetic with IOCG mineralisation.Hydrothermal apatite Lu-Hf dates and molybdenite Re-Os dates demonstrate that mineralisation at Vulcan largely occurred at ca.1.6 Ga,contemporaneous with the world class Olympic Dam deposit.Our data also indicates that the Lu-Hf system in apatite is more robust than the U-Pb system for determining the timing of primary apatite formation in an IOCG system.We further demonstrate that dolomite can retain Lu-Hf growth ages over an extended time period(>1.5 billion years),providing constraints on the timing of primary ore mineral crystallisation during brecciation and IOCG mineralisation.Finally,late Neoproterozoic(ca.589–544 Ma)and Carboniferous(ca.334±7 Ma)Lu-Hf dates were obtained for texturally late Cubearing carbonate veins,illustrating that the carbonate Lu-Hf method allows direct dating of Cu remobilisation events.This has important implications for mineral exploration as the remobilised Cu may have been transferred to younger deposits hosted in Neoproterozoic sedimentary basins overlaying the Olympic IOCG province.展开更多
Arroyo Verde epithermal deposit,in the North Patagonia region of Argentina,is located within the Lower Chon Aike volcanism and is developed between 192.6±2.5 Ma(mineralization host rock)and 189.5±2.6 Ma(over...Arroyo Verde epithermal deposit,in the North Patagonia region of Argentina,is located within the Lower Chon Aike volcanism and is developed between 192.6±2.5 Ma(mineralization host rock)and 189.5±2.6 Ma(overlying lava).Marifil volcanic complex is the host rock for these veins,veinlets and breccias.This particular small deposit has developed low to intermediate sulphidation characteristics,with gangue mineral textures associated with several ore minerals.Electron probe microanalysis determines electrum,silver minerals such as acanthite,and tetrahedrite,related Ag-Cu minerals like jalpaite,mckinstryite,stromeyerite,and base metals like chalcopyrite,sphalerite,galena and pyrite.Fluid inclusions in quartz of two out of five events indicate that these Low Jurassic veins were formed due to subtle boiling and dilution mechanisms and by low-salinity(3.4 wt.%to 6.7 wt.%NaCl Eq)magmatic-hydrothermal fluid at 225 to 310℃.The fluid inclusion measurements that indicate boiling(Event 3)were plotted,and based on this data,we interpret that the Arroyo Verde deposit has been eroded between 550 and 700 m.This particular character has not been previously recorded for other sectors of the eastern north Patagonian region.展开更多
The West Qinling Orogen(WQO)is located in the western part of the Qinling Orogen and in the transition zone of Qilian Orogen,Songpan-Garze Orogen and Yangtze Block,and also the key position of Triassic collision oroge...The West Qinling Orogen(WQO)is located in the western part of the Qinling Orogen and in the transition zone of Qilian Orogen,Songpan-Garze Orogen and Yangtze Block,and also the key position of Triassic collision orogenic event.The study of the Early Triassic strata in the WQO is contributed to analyze the closure process of the paleo-Tethys.We conducted LA-ICP-MS U-Pb dating studies on detrital zircons to determine the provenance,depositional age,and tectonic setting of the Early Triassic Longwuhe Formation in the Lintan area of the WQO.The results show that the majority of the detrital zircons in the Longwuhe Formation are mainly magmatic origin and have characteristic of crust source zircon.The lowest limit of sedimentation of the Longwuhe Formation is constrained to the Early Triassic,with the youngest detrital zircon age of 253±3 Ma.The ages can be divided into five age groups:3346–1636 Ma,with two peak ages of ca.2495 and ca.1885 Ma;1585–1010 Ma,with a peak age at ca.1084 Ma;992–554 Ma,with a peak age at ca.939 Ma;521–421 Ma,with a peak age at ca.445 Ma;418–253 Ma,with a peak age at ca.280 Ma.Apparently,the sources of the Longwuhe Formation include the northern margin of the WQO,the Qilian Orogen(QLO)and the basement of the southern margin of the North China Block(NCB),of which the ancient basement of the southern margin of the NCB is the main source area of the Longwuhe Formation.Combined with previous studies,we propose that the Longwuhe Formation was formed in a fore-arc basin,which is related to the closure of the A’nyemaqen-Mianlüe Ocean from the Early Permian to Early–Middle Triassic due to the northward subduction-collision of the Yangtze Block(YZB).This also indicates that the A’nyemaqen-Mianlüe Ocean has flat subduction characteristics.展开更多
The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thru...The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.展开更多
基金financially supported by the Yunnan Fundamental Research Projects(No.202201AT070077)the Ministry-Province Cooperation Pilot Projects(No.2023ZRBSHZ059)+1 种基金the Major Science and Technology Special Plan of Yunnan Province(No.202202AG050006)the National Natural Science Foundation of China(No.41603032)。
文摘Lower Carboniferous clastic sedimentary rocks(i.e.,the Nanduan Formation)in the Changning-Menglian belt of the southeastern Tibetan Plateau may provide new insights into the tectonic evolution of the Paleo-Tethys Ocean.This paper presents new petrographic,geochemical,and detrital zircon U-Pb age data to constrain the provenance and depositional setting of these rocks.Sandstone samples of the Nanduan Formation are all quartz arenites(Q_(92-99)F_(1-7)L_(0-2))with high SiO_(2)contents(85.1 wt.%-95.2 wt.%;average=90.9 wt.%),indicating high compositional maturity.They exhibit fractionated rare earth element(REE)patterns,with light REE enrichment[(La/Yb)_(N)=6.48-12.1]and negative Eu anomalies(Eu/Eu^(*)=0.53-0.74),and marked negative Sr-Cs-V-Cr-Ni anomalies in upper continental crust-normalised multi-element diagrams.The geochemical features and heavy mineral assemblages suggest that sediments were mainly derived from ancient sedimentary rocks in cratonic interiors or stable continental areas,and were probably deposited in a passive continental margin setting.Detrital zircon U-Pb dating(n=256)of the Nanduan Formation sandstones defines three distinct age peaks in the Pan-African(600-500 Ma),younger Grenvillian(950-850 Ma),and older Grenvillian(1250-1000 Ma).Their zircon age spectra are similar to those of Lower Paleozoic sedimentary rocks(i.e.,the Mengtong and Mengdingjie groups)in the BaoshanSibumasu Block,but significantly different from those of older rocks in the Simao-Indochina and other surrounding blocks(i.e.,the western Yangtze,western Cathaysia,western Qiangtang,Tethyan Himalaya,and Lhasa blocks).This suggests that the Nanduan Formation was deposited at the margin of the Baoshan-Sibumasu Block.Combining the new data presented in this study with published data,we suggest that the Nanduan Formation and underlying Lancang Group were deposited in the same setting during the Early and Late Paleozoic,respectively.
基金supported by the National Key Research and Development Program of China(No.2022YFC2905004)Open Fund from Sino Probe Laboratory(No.SL202405)+4 种基金the Basic Research Fund of Institute of mineral Resource,Chinese Academy of Geological Sciences(No.JKYZD202316)the National Natural Science Foundation of China(Nos.42272093,42230813)China Scholarship Council Project,and the Geological Survey Project(No.DD20230054)Science and Technology Support Project in a new round of prospecting breakthrough strategic action(No.ZKKJ202429)the Central Government Guided Local Scientific and Technological Development Funding Project(No.XZ202401YD0006)。
文摘The giant Jiama deposit is a post-collisional porphyry Cu-polymetallic system located in the Gangdese metallogenic belt of Xizang.It consists of three deposits:The Main deposit,the Zegulangbei deposit,and the South Pit deposit according to exploration and research.The South Pit deposit is a high-grade Cu-Pb-Zn deposit,but its genesis is unclear.To investigate its genesis,a detailed study was conducted on the deposit geology,geochronology and amphibole geochemistry.The results indicate that the weighted average 206Pb/238U age of the zircons from the granite porphyry in the South Pit is 15.38±0.45 Ma,and the molybdenite from the mineralized skarn yield a ReOs isochron age of 15.23±0.22 Ma,in line with the age of the Main deposit(15.7-14.3 Ma).The amphiboles in the granite porphyry of the South Pit,magnesiohornblende and actinolite,are high in Mg and Ca and low in K.They crystallized at temperatures of 705-7490C,pressures of 0.44-0.67 kbar,oxygen fugacity of-14.31--13.69(NNO),and depths of 1.7-2.5 km.Mapping of structure and alteration indicates that the South Pit skarn developed due to the metasomatism of marble of hornfels or carbonate in fold hinge dilation and an interlayer detachment zone by magmatic hydrothermal fluids.According to the age of magmatism and geological features,the South Pit deposit and the Main deposit have originated from the same Miocene magmatism,but the South Pit deposit was affected by the gliding nappe tectonic system.The amphibole geochemistry indicates that the ore-related magma of the South Pit has a high oxygen fugacity and is rich in water.
基金supported by the National Natural Science Foundation of China(Grant Nos.41903025 and 41803048)the National Nonprofit Institute Research Grant of IGGE(Grant Nos.AS2024J03,JY202106 and AS2022P03)+2 种基金the Hebei Key Science and Technology Program(Grant No.19057411Z)the National Science and Technology Major Project(Grant No.2024ZD1002402)the China Geological Survey Project(Grant No.DD20221807).
文摘The Suzhou granitic pluton is the first identified Nb-Ta-rich granite in China.To reveal the genetic link between the sequence of magmatic and hydrothermal evolution and Nb-Ta mineralization in different intrusive phases of the Suzhou granite,whole-rock geochemistry,geochemistry and U-Th-Pb dating of monazite was analyzed.The unique geochemical characteristics show that the Suzhou pluton can be discriminated as an A-type granite.LA-ICP-MS U-Th-Pb dating of monazite in both the medium-and coarse-grained biotite granite(MBG)and the fine-grained biotite granite(FBG)indicates that the granite formed between 124 and 127 Ma.Based on geochemical characteristics and mineral textures,the MBG(Mnz-Ia)and FBG(Mnz-Ib)monazites are classified as magmatic monazites;another monazite(Mnz-II)from the MBG formed during a magmatic-hydrothermal transitional stage.Nb-Ta in the Suzhou pluton gradually concentrated during fractional crystallization and alteration of Ti-rich minerals and biotite.Ultimately,with the involvement of F-Li-rich fluid,Nb-Ta mineralization occurred during the magmatic-hydrothermal transition.The Suzhou pluton is considered part of a 600-km-and NE-SW-trending Nb-rich A-type granite belt together with other Early Cretaceous A-type granites in the Jiangnan Orogen that offers prospects of a new target for Nb-Ta prospecting.
基金funded by the National Science Centre(NCN,Poland)project nos.2018/29/B/ST10/02315 and 2019/33/B/ST10/01728 and the Swedish Research Council(Vetenskapsrådet)grant no.2019-03688.OL is grateful to the Deutsche Forschunggemeinschaft for the support of his COSC-2 research(DFG 867/12-1,13-1,and 13-2)supported by a National Science Foundation(USA)grant EAR2050246.
文摘Detrital zircon geochronology is reported from the c.1200 m thick Cambro-Ordovician sedimentary succession recovered in core from the COSC-2 continental drilling project in the Scandinavian Caledonides.Above a regolith marking the sub-Cambrian peneplain,a lower to middle Cambrian(?)succession comprises conglomerate,sandstone and shale overlain by gravity flows fining upwards into the Alum Shale Formation.First results of detrital zircon geochronology from the Cambrian(?)succession show that the basal section of the autochthonous cover is characterized by mainly late Paleoproterozoic–early Mesoproterozoic detrital grains.The middle part of the succession is dominated by late Paleoproterozoic detritus with minor Mesoproterozoic and Archean input.The upper part of lower Cambrian(?)succession is characterized by Archean to Cambrian detritus.The maximum depositional age is calculated to 530.5±4 Ma for the upper part of the lower Cambrian succession.Two samples from the Lower Ordovician(?)succession above the Alum Shale Formation show predominantly Mesoproterozoic to early Neoproterozoic(1.5–0.9 Ga)ages.The autochthonous lower Cambrian(?)passive margin succession in the lower section is dominated by local detritus,sourced exclusively from the Eastern Segment of the Sveconorwegian Orogen,which includes the basement studied in COSC-2.Up-section,the provenance shifts towards the Transscandinavian Igneous Belt and Svecofennian Orogen sources,with the youngest part of the succession showing a notable input of Neoproterozoic–Cambrian active margin detritus.The Ordovician(?)succession is characterized by populations,likely derived from the Sveconorwegian Orogen,and a minor cratonic contribution.Statistical analysis of detrital zircon datasets across Baltica suggests that the Southern Baltica/Sandomirian Arc,rather than the Timanian Orogen,was a significant source of detrital material across the paleocontinent.The influence of Timanian Orogen grains is limited to northernmost Scandinavia,whereas Sandomirian detritus reached central Scandinavia in the lower to middle Cambrian and remained prevalent in southern Scandinavia into the Lower Ordovician.
基金financially supported by the Geological Survey of China(Grant Nos.DD20240075,and DD20243516)the National Natural Science Foundation of China(Grant No.41872209)Basic Scientific Research Fund of the Institute of Geology,Chinese Academy of Geological Sciences(Grant No.J2314)。
文摘We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and geochemical data,the granitoids in the region can be divided into two age groups:ca.285 Ma and ca.269 Ma.The granitoids of the first group are mainly composed of calc-alkaline to high-K calc-alkaline,weakly peraluminous Ⅰ-type granodiorites with ε_(Hf)(t)values of-19.6 to-4.3,which demonstrates evidence of crustal reworking;the granitoids of the second group,however,mainly consist of A-type granites that are high-K calc-alkaline to shoshonite,metaluminous to weakly peraluminous,and have high 10,000×Ga/Al ratios(2.59-3.12)and ε_(Hf)(t)values ranging from-11.3 to-2.7,all of which demonstrates a mixed crust-mantle source.We interpret the granitoids of the first group to have formed during the subduction of Central Asian oceanic crust and the second group to have formed by the asthenospheric upwelling caused by the formation of slab windows during late ocean ridge subduction.
基金funded by the India-Brazil bilateral co-operation Project:INT/BRAZIL/P-02/2013by Indian Statistical Institute,Geoscience Institute of São Paulo University,Brazil and Department of Geology,University of Calcutta.M.Hueck thanks FAPESP for a post-doctoral fellowship(grant 2019/06838-2).
文摘The Southern Granulite Terrane(Dharwar Craton),South India,is a key unit for understanding the origin of charnockite.New U-Pb and Lu-Hf analyses in zircon crys-tals from 16 samples representing a wide variety of litho-types from the quarries in Kabbaldurga reveal a complex geological history in the Archean and early Paleoprotero-zoic.Magmatic protoliths predominantly record Paleoar-chean ages between 3.4 and 3.2 Ga.Combined U-Pb and Lu-Hf signatures indicate a history of recurrent crustal anatexis,juvenile magmatic input,and felsic injections.Mesoarchaean magmatic charnockites were generated mainly from hornblende-dehydration melting of Paleoar-chaean mafic rocks.In addition,Peninsular Gneissic Com-plex of the Dharwar Craton,commonly described as TTG suites,are likely generated by melting of hydrated basalt.The new data are consistent with the idea of a convecting magmatic cycle and also support the proposal that the southern Dharwar Craton comprises a tilted cross-sec-tion through the Archaean crust.Paleoproterozoic high-temperature event is documented here as a complex unit involving juvenile mafic magmatism,granulite facies imprints and crustal anatexis as well as felsic injections,occurring within a short time period around 2.5 Ga.
基金supported by the National Key R&D Program of China(No.2021YFC2901802)project of the China Geological Survey(No.DD20240073)Key R&D Program of Shaanxi Province(No.2024GH-ZDXM-26).
文摘1.Objective The Eastern Junggar Kalamaili region in Xinjiang constitutes a significant tin metallogenic belt in northwest China(Fig.1a).It hosts four independent tin deposits-Kamusite,Ganliangzi,Beilekuduke,and Sareshenke-from west to east,supplemented by two tin mineralized points,namely Hongtujingzi and Sujiquan(Figs.1b).according to the ore type and the composition of gangue minerals,the tin deposits in the region are classified into two groups:Quartz vein type and greisen type,with the Sareshenke deposit ascribed to the former and the remainder to the latter.
基金Supported by Finance Project of heilongjiang Province(No.HLJKD2015-11)Ministry of Natural Resources Scientific and Technological Achievements(No.20220654)National Natural Science Foundation of China(No.42261134535).
文摘To determine the geological age,petrogenesis,and tectonic setting of Mesozoic volcanic rocks in the Ningyuancun Formation in Xunke area,Lesser Hinggan Range,the zircon U-Pb geochronology,petrographic observations,and geochemical analyses of major and trace elements were conducted in this study.Zircon U-Pb dating showed that the volcanic rocks of the Ningyuancun Formation were formed in the Early Cretaceous(112.97±0.90 Ma).Major element analyses revealed that the content of SiO_(2)weighted from 74.14%to 76.54%,indicating the volcanic rocks to be high-silica and felsic.The content of Al_(2)O_(3)varies from 12.48%to 13.65%.A total alkali content of the volcanic rocks range between 8.46%and 9.56%,with Na_(2)O/K_(2)O ratios from 0.69 to 0.89.This indicated that the volcanic rocks belonged to a highly differentiated calc-alkaline series.Additionally,A/CNK values range from 0.950 to 1.015,and A/NK values vary between 0.999 and 1.127,suggesting a peraluminous characteristic.Trace element analysis showed a right-sloping“V-shaped”REE pattern,with the enrichment in light REEs and a prominent negative anomaly of Eu.The volcanic rocks are enriched in Rb,Th,U,La,and Ce,while Ba,Sr,and Ti are depleted.Rb/Sr ratio ranges from 10.01 to 12.46,Ti/Y ratio is from 51.14 to 95.72,and Ti/Zr ratio is from 5.78 to 6.41.It is suggested that the magma was derived from the partial melting of crustal rocks.This evidenced that the Early Cretaceous high-silica rhyolites were formed in an intracontinental extension in eastern Northeast China during the northwestward subduction of the Pacific Plate.The crustal extension,asthenospheric mantle upwelling and underplating of mantle-derived magmas resulted in the residual crystalline mush in Early Cretaceous mafic magma chambers to erupt.
基金supported by the National Natural Science Foundation of China(No.41872101)the Graduate Innovation Fund of Jilin University(No.2022046)。
文摘During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific subduction.However,controversy exists about the Paleo-Pacific subduction's initiation time.This study uses detrital zircon U-Pb ages to discuss the Late Triassic source-tosink system in the SESCB.It provides some references for the Paleo-Pacific subduction process based on crucial age information and zircons'trace elements.The paleogeography and similarity of detrital zircon age distribution indicate that three sinks were found in the SESCB during the Late Triassic:1.the Yangchun-Kaiping-Gaoming area,comprising major age ranges of 260-220,460-400,and 1200-800 Ma,which might be sourced from the Yunkai terrane;2.the Jiexi-Kanshi-Nanjing area,characterized by the significant age component of 2000-1800 Ma,which corresponded to the Wuyi terrane;3.the Xinan area,consisting of significant age groups of 290-250 and 380-320 Ma,which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific subduction.Note that 290-250 Ma zircons were widely distributed in the Upper Triassic strata,and their trace elements suggested the existence of a magmatic arc near the SESCB during the 290-250 Ma.Thus,we propose that the Paleo-Pacific subduction might have begun in the Early Permian.
文摘The Weining Beishan area of Ningxia Hui Autonomous Region is located at on the western edge of the Helanshan tectonic belt,which is a tectonic joint among Alxa Block,Ordos Block,and North Qilian orogenic belt.However,the tectonic evolution of this area remains unclear due to the lack of magmatic information.This paper conducted researches on geochronology,geochemistry,and Sr-Nd-Hf isotopes of the diorite porphyrites exposed in the Weining Beishan area.The zircon U-Pb dating yields two ages of 145.0±1.1 and 146.2±1.5 Ma,and the whole-rock geochemical data indicate that the diorite porphyrites are metaluminous to weakly peraluminous and high-K calc-alkaline series.The characteristics of highly initial^(87)Sr/^(86)Sr ratios(0.70816 to 0.71047),negativeε_(Nd)(t)(−8.9 to−8.4),and negativeε_(Hf)(t)(−13.8 to−21.2)indicate that the diorite porphyrites originated from partial melting of the middle-lower ancient crust related to the North China Craton.Combined with the regional geology,we suggested that partial melting was triggered by a tectonic activity of deep faults cutting through the crust under the regional stress transformation from compressing to extension during the Late Jurassic–Early Cretaceous,which is probably related to the westward subduction of the Paleo-Pacific Plate.
基金We thank the National Science Foundation of China for funding S.V.Hohl with a Research Fund for International Excellent Young Scientists(RFIS-II),the stromatolite geochemical archive(funding no.42150610481)。
文摘Some of the earliest bio-sedimentary records of life on Earth are represented by microbial carbonates,which are also critical geochemical archives of ancient seawater chemistry and the environmental circumstances in which they precipitated.Reconstructing paleo-microbial environments on Earth and potentially other planets requires precise determination of the depositional ages of these materials.The(abiogenic)carbonate geochemistry communities can now use developments in in-situ laser ablation U-Pb dating using inductively coupled plasma mass spectrometry(LA-ICP-MS).Due to the effects of impurity mixing and diagenesis,microbial carbonates have received little geochronological study despite their broad relevance for understanding ancient seawater’s environmental conditions and geochemical compositions.This study demonstrates using time-of-flight mass spectrometry(TOF-MS)to perform quick,quantitative elemental mapping before U-Pb spot dating to improve experiment success rates and data reliability and offers four practical application examples.
基金supported by the National Natural Science Foundation of China(Grant Nos.42262026,42072259).
文摘The Triassic was a crucial period in the tectonic evolution of the South China Block.Research on tectonic deformation during this period provides information on intracontinental orogenic mechanisms in South China.In this study,alongside thermochronological analyses,we examine the macroscopic and microscopic structural features of the Rongxian ductile shear zone,located south of the Darongshan granite in the southeastern part of Guangxi Province,on the southern margin of South China.Sinistral shear is indicated by the characteristics of rotatedσ-type feldspar porphyroclasts,stretching lineations defined by elongated quartz grains and the orientations of quartz c-axes.LA-ICP-MS U-Pb dating of zircons from two samples of granitic mylonite and one of granite yielded ages of ca.256 Ma.Furthermore,two samples of granitic mylonite yield muscovite^(40)Ar/^(39)Ar plateau ages of 249-246 Ma.These results indicate that the Rongxian ductile shear zone resulted from Early Triassic deformation of the late Permian Darongshan granite.This deformation was likely related to the closure of the eastern Paleo-Tethys Ocean and the subsequent collision of the South China and Indochina blocks,during the early stage of the Indosinian orogeny.
基金granted by Opening Foundation of State Key Laboratory of Continental Dynamics(Grant No.21LCD08),Northwest University。
文摘The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ages of~101 and~98 Ma,and they have a high formation temperature(~910℃)and low oxygen fugacity value,indicating crystallization condition at low pressure in the upper crust with temperature of 678℃.The Qishan and Kuiqi miarolites are characterized by enrichment in SiO_(2) and high-K alkali,depletion in Ca and Mg,and belong to the high-K weak peraluminous rock series.The samples are enriched in HFSEs(i.e.,Ta,Zr and Hf)and LILEs(i.e.,Ba,P and Sr),depleted in Ba and Sr with the negative anomaly of Eu.In the primitive mantle normalized trace element spider diagram,the samples show a right-inclined‘seagull-type’pattern,combined the ratios of(La/Yb)_(N),10000×Al/Ga,Rb/Nb and Nb/Ta etc.,they were proved to be alkaline A-type granite.Combined the characterize of the trace elements,they were derived from clay-rich source accompanied pelite melting,and subjected to K-feldspar crystallization fractional.The values of ε_(Hf)(t)and tDM2 are distributed in the range of-2.8 to 3.3 with~1.2 Ga,and-6.0 to 4.0 with~1.2 Ga,revealing that they were generated from the Mesoproterozoic Cathaysia basement rocks.The comprehensive research reveals the Kuiqi and Qishan intrusions derived from crust-mantle mixing and partial melting of the crust,respectively,resulting from lithospheric extension generated by the Paleo-Pacific Plate subducted into the European-Asian Plate.
基金funded by the National Natural Science Foundation of China (2019M653840XB)the National Natural Science Foundation of China (41972043 and 42062006)。
文摘Geochemistry, zircon U–Pb geochronology, and Hf isotope data for the Early Paleozoic granites in the Baoshan Block reveal the Early Paleozoic tectonic evolution of the Proto-Tethys. The samples are high-K, calcalkaline, strongly peraluminous rocks with A/CNK values of 1.37–1.46, are enriched in SiO2, K2O, and Rb, and are depleted in Nb, P, Ti, Eu, and heavy rare earth elements,which indicates the crystallization fractionation of the granitic magma. Zircon U–Pb dating indicates that they formed in ca. 480 Ma. The Nansa granites have εHf(t) values ranging from-16.04 to 4.36 with corresponding TC DMages of 2.10–0.81 Ga, which suggests the magmas derived from the partial melting of ancient metasedimentary with minor involvement of mantle-derived components. A synthesis of data for the Early Paleozoic igneous rocks in the Baoshan block and adjacent(Tengchong,Qiangtang, Sibumasu, Himalaya, etc.) blocks indicates that these blocks were all aligned along the proto-Tethyan margin of East Gondwana in the Early Paleozoic. The Early Paleozoic S-type granites from Nansa were generated in a high-temperature and low-pressure(HTLP) extensional tectonic setting, which resulted from Andean-type orogeny instead of the final assembly of Gondwana or crustal extension in a non-arc environment. In certain places, an expanding environment may exist in opposition to the tectonic backdrop of the lithosphere’s thickening and shortening, leading the crust to melt and decompress,mantle-derived materials to mix, and a small quantity of peraluminous granite to emerge.
基金financially supported by the China Geological Survey(Nos.DD20190370 and 121201111120117).
文摘In situ zircon U-Pb geochronological and Lu-Hf isotope studies of detrital zircons from Late Mesoproterozoic to Early Neoproterozoic sedimentary units on the southwestern margin of the Yangtze Block have important implications for the tectonic evolution of the Yangtze Block.The Huili Group contains zircons whose ages are mainly Late Archean to Mesoproterozoic(2650-2450,2100-1800,and 1350-1150 Ma).The Dengxiangying Group has one major age population of 1900-1600 Ma,and two subordinate age populations of 1350-1100 and 2300-2000 Ma.Yanbian Group sedimentary rocks have a zircon age population mainly in the range of 970-850 Ma,contemporaneous with the ages of widespread arc-related magmatism in the western Yangtze Block.Combining these results with previous work,the Huili and Dengxiangying groups were most likely deposited during ca.1160 to 1000 Ma in an intra-continental rift basin setting,while the Yanbian Group accumulated during>920 to 782 Ma in a back-arc basin setting at the southwestern margin of the Yangtze Block.In addition,all these results further suggest a tectonic transition from a continental rift basin to a convergent environment at the southwestern margin of the Yangtze Block at 1000-970 Ma.
基金supported financially by the National Natural Science Foundation of China(No.42272111)the Second Tibetan Plateau Scientific Expedition Program(Nos.2019QZKK0204,2019QZKK0205).
文摘Detrital U-bearing minerals(e.g.,zircon,apatite)U-Pb ages with specific trace-element geochemistry,are frequently used in provenance analyses.In this study,we focus on the Yarlung River drainage in South Xizang,characterized by two distinct lithologic units:The Gangdese batholith to the north(mainly granitoids)and the Tethyan Himalaya(mainly sedimentary rocks)to the south,which plays a crucial role in the erosion of the Tibetan Plateau.To constrain the provenance of the Yarlung River Basin,we performed trace-element and U-Pb age analyses of detrital apatite from the river sands of the Yarlung River and its tributaries.Our findings indicate that the detrital apatite U-Pb age patterns of the north tributaries exhibit main peaks at approximately 40 and 60 Ma,consistent with the corresponding U-Pb age patterns of detrital zircon published.Further,their trace element casts fall mainly in the Type I granite region,also indicating the Gangdese arc-dominated source.However,those of the south tributaries(∼60–20 Ma)exhibit a different age distribution from the detrital zircon U-Pb groups(∼110–150,∼500,and 1100 Ma),suggesting that the detailed apatite U-Pb signals can provide excellent constraints on the provenance of igneous and metamorphic rock sources but less so for sedimentary rock sources.Combined with previous detrital zircon data in the study area,our detrital apatite information can highlight young metamorphic events from a complex background(i.e.,Niyang and Nianchu rivers),which offers additional constraints on the provenance of the Yarlung River Basin.Generally,a combination of geochemistry and geochronology of multi-detrital heavy minerals,such as zircon and apatite,can provide powerful tools for provenance analysis.
基金supported by an Accelerated Discovery Initiative Grant(ADI RD02/260),entitled‘Integrated Exploration Under Deep Cover‘with joint funding from Fortescue and the Government of South AustraliaSG was further supported by an Australian Research Council Future Fellowship(FT210100906)The acquisition of isotope-dilution Lu-Hf dates was financially supported by the Mineral Exploration Cooperative Research Centre whose activities are funded by the Australian Government’s Cooperative Research Centre Program。
文摘The development of laser ablation inductively coupled plasma quadrupole tandem mass spectrometry(LA-ICP-Q-MS/MS)opens new opportunities to rapidly date a variety of hydrothermal minerals.Here we present in situ Lu-Hf and Re-Os dates for hydrothermal apatite and molybdenite,respectively.We further report the first in situ Lu-Hf dates for bastnäsite,dolomite,and siderite,and assess their potential for constraining ore deposit geochronology.For method validation,we report isotope-dilution Lu-Hf dates for apatite reference material Bamble-1(1102±5 Ma)and calcite reference material ME-1(1531±7 Ma),enabling improved accuracy on matrix-matched calibration for LA-ICP-MS/MS Lu-Hf dating.The new methods are applied to the Vulcan Iron-Oxide Copper-Gold(IOCG)prospect in the Olympic Cu-Au Province of South Australia.Such deposits have been difficult to accurately date,given the general lack of reliable mineral geochronometers that are cogenetic with IOCG mineralisation.Hydrothermal apatite Lu-Hf dates and molybdenite Re-Os dates demonstrate that mineralisation at Vulcan largely occurred at ca.1.6 Ga,contemporaneous with the world class Olympic Dam deposit.Our data also indicates that the Lu-Hf system in apatite is more robust than the U-Pb system for determining the timing of primary apatite formation in an IOCG system.We further demonstrate that dolomite can retain Lu-Hf growth ages over an extended time period(>1.5 billion years),providing constraints on the timing of primary ore mineral crystallisation during brecciation and IOCG mineralisation.Finally,late Neoproterozoic(ca.589–544 Ma)and Carboniferous(ca.334±7 Ma)Lu-Hf dates were obtained for texturally late Cubearing carbonate veins,illustrating that the carbonate Lu-Hf method allows direct dating of Cu remobilisation events.This has important implications for mineral exploration as the remobilised Cu may have been transferred to younger deposits hosted in Neoproterozoic sedimentary basins overlaying the Olympic IOCG province.
文摘Arroyo Verde epithermal deposit,in the North Patagonia region of Argentina,is located within the Lower Chon Aike volcanism and is developed between 192.6±2.5 Ma(mineralization host rock)and 189.5±2.6 Ma(overlying lava).Marifil volcanic complex is the host rock for these veins,veinlets and breccias.This particular small deposit has developed low to intermediate sulphidation characteristics,with gangue mineral textures associated with several ore minerals.Electron probe microanalysis determines electrum,silver minerals such as acanthite,and tetrahedrite,related Ag-Cu minerals like jalpaite,mckinstryite,stromeyerite,and base metals like chalcopyrite,sphalerite,galena and pyrite.Fluid inclusions in quartz of two out of five events indicate that these Low Jurassic veins were formed due to subtle boiling and dilution mechanisms and by low-salinity(3.4 wt.%to 6.7 wt.%NaCl Eq)magmatic-hydrothermal fluid at 225 to 310℃.The fluid inclusion measurements that indicate boiling(Event 3)were plotted,and based on this data,we interpret that the Arroyo Verde deposit has been eroded between 550 and 700 m.This particular character has not been previously recorded for other sectors of the eastern north Patagonian region.
基金supported financially by the National Nature Sciences Foundation of China(Nos.41872235,42172236,41872233,42072267,41802234,41602229 and 41502191)China Scholarship Council(No.201806565026)+3 种基金Natural Science Basic Research Plan in Shaanxi Province of China(Nos.2019JM-312,2019JQ-090 and 2019JQ-209)China Geological Survey(Nos.12120114041201 and DD2016007901)China Postdoctoral Science Foundation(No.2016M592726)the Fundamental Research Funds for the Central Universities of China(Nos.300102270202,300103120009,202110710062,300103183081,300104282717,300102279204 and 201810710233).
文摘The West Qinling Orogen(WQO)is located in the western part of the Qinling Orogen and in the transition zone of Qilian Orogen,Songpan-Garze Orogen and Yangtze Block,and also the key position of Triassic collision orogenic event.The study of the Early Triassic strata in the WQO is contributed to analyze the closure process of the paleo-Tethys.We conducted LA-ICP-MS U-Pb dating studies on detrital zircons to determine the provenance,depositional age,and tectonic setting of the Early Triassic Longwuhe Formation in the Lintan area of the WQO.The results show that the majority of the detrital zircons in the Longwuhe Formation are mainly magmatic origin and have characteristic of crust source zircon.The lowest limit of sedimentation of the Longwuhe Formation is constrained to the Early Triassic,with the youngest detrital zircon age of 253±3 Ma.The ages can be divided into five age groups:3346–1636 Ma,with two peak ages of ca.2495 and ca.1885 Ma;1585–1010 Ma,with a peak age at ca.1084 Ma;992–554 Ma,with a peak age at ca.939 Ma;521–421 Ma,with a peak age at ca.445 Ma;418–253 Ma,with a peak age at ca.280 Ma.Apparently,the sources of the Longwuhe Formation include the northern margin of the WQO,the Qilian Orogen(QLO)and the basement of the southern margin of the North China Block(NCB),of which the ancient basement of the southern margin of the NCB is the main source area of the Longwuhe Formation.Combined with previous studies,we propose that the Longwuhe Formation was formed in a fore-arc basin,which is related to the closure of the A’nyemaqen-Mianlüe Ocean from the Early Permian to Early–Middle Triassic due to the northward subduction-collision of the Yangtze Block(YZB).This also indicates that the A’nyemaqen-Mianlüe Ocean has flat subduction characteristics.
基金funded by the National Natural Science Foundation of China(41872232)the Beijing Geological Survey Project(PXM 2016-158203-000008,PXM 2018-158203-000014)the Beijing Innovation Studio(Urban Geology,Active Structure,and Monitoring).
文摘The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.
