The conventional view suggests that the subduction of the South China Sea plate beneath Luzon occurred due to the oceanic lithosphere’s high density,facilitating subduction initiation.However,before the South China S...The conventional view suggests that the subduction of the South China Sea plate beneath Luzon occurred due to the oceanic lithosphere’s high density,facilitating subduction initiation.However,before the South China Sea opened,a continental margin likely existed,meaning that Luzon was directly adjacent to the continental margin rather than the oceanic basin.This would make subduction initiation more challenging.Here,we propose a new model suggesting that during the formation of the South China Sea,extensive mafic magmatic underplating occurred along its continental margin.The high-density magmatic additions may have increased the overall density of the continental margin,potentially exceeding that of Luzon,thereby enabling subduction to proceed.展开更多
The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as sour...The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as source rocks,reservoirs,seals,migration pathways,and trapping mechanisms.However,due to the limited number of wells drilled in the region,there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation.To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system,particularly source rock,an integrated geochemical and resistivity log analysis was carried out.The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents(TOC<1 wt%),kerogen yield(<1 Mg HC/g),and Hydrogen Index(<100 Mg HC/g),primarily composed of TypeⅢ(gas-prone)to TypeⅣ(inert)kerogens.These sediments have undergone varying levels of thermal maturity,ranging from post-mature(within Cretaceous),matured(in Paleocene)to immature(in Eocene)thermal states.The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration,resulting in a reduction of both organic matter(OM)content and source potential compared to the Eocene and Paleocene samples.This observation is consistent with the estimated paleotemperature(T)and resistivity log(ILD)along the depth profile,which have mapped local thermal alteration increasing from base Paleocene to Cretaceous.These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin.This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks.These intrusions pose a potential risk in petroleum exploration,especially when they intrude into matured source rock intervals.展开更多
Downward transport of stratospheric air into the troposphere(identified as stratospheric intrusions)could potentially modify the radiation budget and chemical of the Earth's surface atmosphere.As the highest and l...Downward transport of stratospheric air into the troposphere(identified as stratospheric intrusions)could potentially modify the radiation budget and chemical of the Earth's surface atmosphere.As the highest and largest plateau on earth,the Tibetan Plateau including the Himalayas couples to global climate,and has attracted widespread attention due to rapid warming and cryospheric shrinking.Previous studies recognized strong stratospheric intrusions in the Himalayas but are poorly understood due to limited direct evidences and the complexity of the meteorological dynamics of the third pole.Cosmogenic^(35)S is a radioactive isotope predominately produced in the lower stratosphere and has been demonstrated as a sensitive chemical tracer to detect stratospherically sourced air mass in the planetary boundary layer.Here,we report 6-month(April–September 2018)observation of^(35)S in atmospheric sulfate aerosols(^(35)SO_(4)^(2-))collected from a remote site in the Himalayas to reveal the stratospheric intrusion phenomenon as well as its potential impacts in this region.Throughout the sampling campaign,the^(35)SO_(4)^(2-)concentrations show an average of 1,070±980 atoms/m^(3).In springtime,the average is 1,620±730 atoms/m^(3),significantly higher than the global existing data measured so far.The significant enrichments of^(35)SO_(4)^(2-)measured in this study verified the hypothesis that the Himalayas is a global hot spot of stratospheric intrusions,especially during the springtime as a consequence of its unique geology and atmospheric couplings.In combined with the ancillary evidences,e.g.,oxygen-17 anomaly in sulfate and modeling results,we found that the stratospheric intrusions have a profound impact on the surface ozone concentrations over the study region,and potentially have the ability to constrain how the mechanisms of sulfate oxidation are affected by a change in plateau atmospheric properties and conditions.This study provides new observational constraints on stratospheric intrusions in the Himalayas,which would further provide additional information for a deeper understanding on the environment and climatic changes over the Tibetan Plateau.展开更多
The Central Asian Orogenic Belt(CAOB) resulted from accretion during the Paleozoic subduction of the PaleoAsian Ocean. The Xilinhot area in Inner Mongolia is located in the northern subduction zone of the central-east...The Central Asian Orogenic Belt(CAOB) resulted from accretion during the Paleozoic subduction of the PaleoAsian Ocean. The Xilinhot area in Inner Mongolia is located in the northern subduction zone of the central-eastern CAOB and outcropped a large number of late Paleozoic mafic intrusions. The characteristics of magma source and tectonic setting of the mafic intrusions and their response to the closure process of the Paleo-Asian Ocean are still controversial. This study presents LA-ICPMS zircon U-Pb ages and geochemical features of mafic intrusions in the Xilinhot area to constrain the northward subduction of the Paleo-Asian Ocean. The mafic intrusions consist of gabbro, hornblende gabbro, and diabase. Their intrusion times can be divided into three stages of 326-321 Ma, 276 Ma and 254 Ma by zircon U-Pb ages. The first two stages of the 326-276 Ma intrusions mostly originated from subduction-modified continental lithospheric mantle sources that underwent a variable degree partial melting(5-30%), recording the subduction of oceanic crust. The third stage of the 254 Ma mafic rocks also show arc-related features. The primary magma compositions calculated by PRIMELT2 modeling on three samples of ~326 Ma and two samples of ~254 Ma show that these mafic samples are characterized by a variable range in SiO2(47.51-51.47 wt%), Al2O3(11.46-15.55 wt%), ΣFeO(8.27-9.61 wt%), MgO(13.01-15.18 wt%) and CaO(9.13-11.67 wt%), consisting with the features between enriched mantle and lower continental crust. The source mantle melting of mafic intrusions occurred under temperatures of 1302-1351°C and pressures of 0.92-1.30 GPa. The magmatic processes occurred near the crust-mantle boundary at about 33-45 km underground. Combined with previous studies, it is concluded that Carboniferous to early Permian(~326-275 Ma) northward subduction of the Paleo-Asian oceanic crust led to the formation of the mafic magmatism in the Baolidao arc zone. The whole region had entered the collision environment at ~254 Ma, but with subduction-related environments locally. The final collision between the North China craton and the South Mongolian microcontinent may have lasted until ca. 230 Ma.展开更多
There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province （LIP）; namely, small ultramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element （PG...There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province （LIP）; namely, small ultramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element （PGE）-bearing sulfide deposits and large mafic layered intrusions that host giant Ti-V magnetite deposits in the Panxi region. However, except for their coeval ages, the genetic relations between the ore-bearing intrusions and extrusive rocks are poorly understood. Phase equilibria analysis （Q-PI-OI-Opx-Cpx system） has been carried out to elucidate whether ore-bearing Panzhihua, Xinjie and Limahe intrusions are co-magmatic with the picrites and flood basalts （including high-Ti, low-Ti and alkali basalts）, respectively. In this system, the parental magma can be classified as silica-undersaturated olivine basalt and silica-saturated tholeiite. The equivalents of the parental magma of the Xinjie and Limahe peridotites and picrites and low-Ti basalts are silica-undersaturated, whereas the Limahe gabbro-diorites and high-Ti basalts are silica-saturated. In contrast, the Panzhihua intrusion appears to be alkali character. Phase equilibria relations clearly show that the magmas that formed the Panzhihua intrusion and high-Ti basalts cannot be co-magmatic as there is no way to derive one liquid from another by fractional crystallization. On the other hand, the Panzhihua intrusion appears to be related to Permian alkali intrusions in the region, but does not appear to be related to the alkali basalts recognized in the Longzhoushan lava stratigraphy. Comparably, the Limahe intrusion appears to be a genetic relation to the picrites, whereas the Xinjie intrusion may be genetically related to be low-Ti basalts. Additionally, the gabbro-diorites and peridotites of the Limahe intrusion are not co-magmatic, and the former appears to be derived liquid from high-Ti basalts.展开更多
Late Paleozoic mafic-intermediate intrusions are widespread in the central Tianshan belt, but their tectonic settings remain controversial. Petrogenesis of these intrusions can provide insights into the tectonic evolu...Late Paleozoic mafic-intermediate intrusions are widespread in the central Tianshan belt, but their tectonic settings remain controversial. Petrogenesis of these intrusions can provide insights into the tectonic evolution of the belt and its adjacent areas. This study presents new whole-rock geochemical and zircon U-Pb geochronology and Hf isotopic data for the Yaxi diorite and Qianzishan gabbro on the northern margin of the central Tianshan(NW China). Zircon U-Pb dating yielded the magma crystallization ages of 313±4 and 295±4 Ma for the Yaxi diorite and Qianzishan gabbro, respectively. They have lower Mg# values, Ni and Cr contents than typical mantle-derived primary melt, with negative correlations between MgO, TFeO and SiO2 contents, indicating clinopyroxene and olivine fractionation during magma evolution. They are characterized by enrichment of large ion lithophile elements(e.g., Rb, Ba and Sr) and depletion of high field strength elements(e.g., Nb, Ta and Ti) with high Ba/Th and Rb/Y, suggesting that their mantle sources had been metasomatized by slab-derived fluids. In addition, the Qianzishan gabbro has high Al2 O3 contents(19.54 wt.%–20.88 wt.%) and positive Eu anomalies(Eu/Eu*=1.09–1.42), which can be attributed to accumulation of plagioclase. Geochemical and zircon Hf isotopic compositions reveal that both the Yaxi diorite and Qianzishan gabbro were derived from depleted lithospheric mantle in the spinel stability field with insignificant crustal contamination. In association with previous investigations, we suggest that the Yaxi and Qianzishan intrusions were emplaced in a subduction-related environment, which means that the subduction of the Junggar Ocean lasted at least to the earliest Permian.展开更多
Many important metal resources, such as Ni （Cu, Co）, PGE, exist in magmatic sulfide deposits, are a hot spot in geological research. We divide the magmatic sulphide deposits in China into four types according to the...Many important metal resources, such as Ni （Cu, Co）, PGE, exist in magmatic sulfide deposits, are a hot spot in geological research. We divide the magmatic sulphide deposits in China into four types according to their tectonic setting, intruding mode, ore deposit mode, main metallogenic elements. The four types are as follows： （1） Small-intrusion deposits in paleo-continent; （2） Smallintrusion deposits in continental flood basalt; （3） Small-intrusion deposits in orogenic belt; and （4） The deposits associated with ophiolites. On the basis of the classification, we put forward that the main magmatic metallogenic type in China is small-intrusion metallogeny, and describe its characteristics from small intrusions related concept, three geologic settings, three volcanic-intrusive assemblages and metallogenic key factors. According to the experiences of prospecting at home and abroad, we point out that there is big potential in prospecting small-intrusion deposits, which need further study. At last, we indicate that small-intrusion metallogeny not only widely distributes in mafic-ultramafic intrusions, but also has an important economic value and scientific significance in intermediate-acid intrusions.展开更多
The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zirc...The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.展开更多
The northern margin of the North China Craton(NCC)contains widespread Permian magmatic rocks,but the origin of these rocks remains controversial.This uncertainty hampers us from better understanding of tectonic framew...The northern margin of the North China Craton(NCC)contains widespread Permian magmatic rocks,but the origin of these rocks remains controversial.This uncertainty hampers us from better understanding of tectonic framework and evolution of the eastern Paleo-Asian Ocean,particularly with respect to its final-stage subduction and closure time.To address these questions,this study presents petrological,zircon U-Pb geochronological,whole-rock geochemical and in situ zircon Hf isotopic data for these Permian mafic intrusions in the northern margin of the NCC.Precise zircon U-Pb dating results indicate that these mafic intrusions were emplaced in the Middle Permian(ca.260 Ma).Geochemically,the studied mafic intrusions have high MgO and transition metals element contents,with high Mg^(#) values,indicating a mantle origin.These mafic intrusions are characterized by enrichments in large ion lithophile elements(LILEs;e.g.,Rb,Ba,and K)and light rare earth elements(LREEs),and depletions in high field strength elements(HFSEs;e.g.,Nb,Ta,and Ti)and heavy rare earth elements(HREEs),indicating that they were formed in a subduction-related setting.These geochemical features,together with zircon ε_(Hf)(t)values(-1.1 to+11.2),indicate that their parental magmas were derived from partial melting of heterogeneous mantle wedge metasomatized by subduction-related fluids,with the contributions of slab sediments.The studied mafic intrusions also show wide range of major and trace elements contents,and variable Mg^(#) values,Eu and Sr anomalies,suggesting that their parental magmas had undergone variable degrees of fractional crystallization.Together with the E-W trending Permian continental arc along the northern margin of the NCC,we confirm that the generation of the Middle Permian mafic intrusions was related to southward subduction of the Paleo-Asian oceanic lithosphere beneath the NCC and the Paleo-Asian Ocean had not closed prior to the Middle Permian.展开更多
A mosaic of terranes or blocks and associated Late Paleozoic to Mesozoic sutures are characteristics of the north Sanjiang orogenic belt （NSOB）. A detailed field study and sampling across the three magmatic belts in...A mosaic of terranes or blocks and associated Late Paleozoic to Mesozoic sutures are characteristics of the north Sanjiang orogenic belt （NSOB）. A detailed field study and sampling across the three magmatic belts in north Sanjiang orogenic belt, which are the Jomda-Weixi magmatic belt, the Yidun magmatic belt and the Northeast Lhasa magmatic belt, yield abundant data that demonstrate multiphase magmatism took place during the late Paleozoic to early Mesozoic. 9 new zircon LA-ICP-MS U-Pb ages and 160 published geochronological data have identified five continuous episodes of magma activities in the NSOB from the Late Paleozoic to Mesozoic： the Late Permian to Early Triassic （c. 261-230 Ma）; the Middle to Late Triassic （c. 229-210 Ma）; the Early to Middle Jurassic （c. 206-165 Ma）; the Early Cretaceous （c. 138-110 Ma） and the Late Cretaceous （c. 103-75 Ma）. 105 new and 830 published geochemical data reveal that the intrusive rocks in different episodes have distinct geochemical compositions. The Late Permian to Early Triassic intrusive rocks are all distributed in the Jomda-Weixi magmatic belt, showing arc-like characteristics; the Middle to Late Triassic intrusive rocks widely distributed in both Jomda-Weixi and Yidun magmatic belts, also demonstrating volcanic-arc granite features; the Early to Middle Jurassic intrusive rocks are mostly exposed in the easternmost Yidun magmatic belt and scattered in the westernmost Yangtza Block along the Garze-Litang suture, showing the properties of syn-collisional granite; nearly all the Early Cretaceous intrusive rocks distributed in the NE Lhasa magmatic belt along Bangong suture, exhibiting both arc-like and syn-collision-like characteristics; and the Late Cretaceous intrusive rocks mainly exposed in the westernmost Yidun magmatic belt, with A-type granite features. These suggest that the co-collision related magmatism in Indosinian period developed in the central and eastern parts of NSOB while the Yanshan period co-collision related magmatism mainly occurred in the west area. In detail, the earliest magmatism developed in late Permian to Triassic and formed the Jomda-Wei magmatic belt, then magmatic activity migrated eastwards and westwards, forming the Yidun magmatic bellt, the magmatism weakend at the end of late Triassic, until the explosure of the magmatic activity occurred in early Cretaceous in the west NSOB, forming the NE Lhasa magmatic belt. Then the magmatism migrated eastwards and made an impact on the within-plate magmatism in Yidun magmatic belt in late Cretaceous.展开更多
The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite p...The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite porphyry. The K20 content of majority of these rocks is greater than 3%, and, in the K20-SiO2 diagram, all the samples fall into the high-K calc-alkaline to shoshonitic fields. They are enriched in light rare earth elements （LREEs） and depleted in heavy rare earth elements （HREEs; LaN/YbN = 14.3-21.2）, and show slightly negative Eu anomalies （6Eu = 0.77-1.00）. These rocks have high K, Rb, Sr, and Ba contents; moderate to high enrichment of compatible elements （Cr = 36.7-79.9 ppm, Co = 9.6-16.4 ppm, and MgO = 2.2%-3.4%）; low Nb, Ta, and Ti contents, and characteristic of low high field strength elements（HFSEs） versus incompatible elements ratios （Nb/Th = 0.75, Nb/La = 0.34） and incompatible elements ratios （Nb/U = 3.0 and Ce/Pb = 5.1, Ba/Rb = 12.0）. These rocks exhibit restricted Sr and Nd isotopic compositions, with （87Sr/S6Sr）i values ranging from 0.7044 to 0.7069 and ENd（t） values from -2.8 to -2.2. The Sr-Nd isotope systematic and specific trace element ratios suggest that Langdu high-K calc-alkaline intrusive rocks derived from a metasomatized mantle source. The unique geochemical feature of intrusive rocks can be modeled successfully using different members of a slightly enriched mantle, a slab-derived fluid, and terrigenous sediments. It can be inferred that the degree of partial melting and the presence of specific components are temporally related to the tectonic evolution of the Zhongdian island arc. Formation of these rocks can be explained by the various degrees of melting within an ascending region of the slightly enriched mantle, triggered by the subduction of the Garz^--Litang ocean, and an interaction between the slab-derived fluid and the terrigenous sediments.展开更多
The existing high-resolution hydrographic data in the western tropical Pacilit; Ocean are used to explore the spatial distribution and primary characteristics of thermohaline intrusions in the thermocline. Statistics ...The existing high-resolution hydrographic data in the western tropical Pacilit; Ocean are used to explore the spatial distribution and primary characteristics of thermohaline intrusions in the thermocline. Statistics show that the vertical scales of intrusions are 20-40 m in the upper thermocline （22.0-26.0δ0） and 40-80 m in the lower thermocline （26.0-27.2δ0）. In the upper thermocline, the most intensive intrusions exist at the equatorial front （EF） where north/sonth Pacilic water masses converge, anti Ihe westward spreading of the north Pacilic tropical waler （NPTW） in the Philippines Sea also produces patches of intrusions surrounding its high-salinity tongue. In the lower thermocline, intrusions are also strong at the tropical front （TF） which is the boundary between the north Pacilic subtropical/tropical waters. At the bottom of the thermocline （at about 27.0δ0）, intrusions mainly exist near the western boundary, which are produced by intermediate water convergence through the advection of subthermocline western boundary Ilows. Most strikingly a ＂C＂-shape distribution of intrusions at around 26.4δ0 is revealed, covering the vicinity of the EF the TE and the Mindanao Current （MC）, i.e., tile western boundary pathway ol the norlh Pacilic subtrnpical cell （STC）. Synoptic section analysis reveals that intrusions are more prominent on the warm/sally flank ot the fronts, implying more cross-front tongues of cold/fresh water. Among the intrusions, those at the EF are of best lateral coherence which implies a unique driving mechanism involving near-inertial velocity perturbations near the equator.展开更多
Baddeleyite（ZrO2）is today recognized as a key mineral for dating the emplacement of mantle-derived rocks such as gabbros,alkaline（Si-poor）rocks and dolerite dykes and sills,but also in hydrothermally-driven
1.Objectives The porphyry copper deposits (PCD) are usually hosted in a multistage intrusive complex but only causallyrelated tospecific magma of high oxidation state and water content. The copper enrichment of the po...1.Objectives The porphyry copper deposits (PCD) are usually hosted in a multistage intrusive complex but only causallyrelated tospecific magma of high oxidation state and water content. The copper enrichment of the porphyry system is caused by accumulation during magmatic differentiation (Hou ZQ et al., 2015). Thus, study on magmatic evolution and Cu mineralization process is important for understanding the formation of PCD.展开更多
The transportation of magma in sedimentary basins often occurs through extensive dyke-sill networks.The role of sills on the plumbing system in rifted margins and the impact of sills on hydrocarbon reservoirs of prosp...The transportation of magma in sedimentary basins often occurs through extensive dyke-sill networks.The role of sills on the plumbing system in rifted margins and the impact of sills on hydrocarbon reservoirs of prospective sedimentary basins has long been an area of great industrial interest and scientific debate.Based on 2D seismic reflection,we present data on how the sills emplaced to form a magmatic plumbing system of the volcanic system for the Zhongjiannan Basin(ZJNB).The results show that sixty-nine sills and fourteen forced folds have been identified.The distribution and geometry of the sills suggest that magma flowed from west to east and then ascended to near the surface.The onlap relationship of the forced folds indicates that the timing of magmatic activities can be constrained at ca.0.2 Ma.The spatial and temporal occurrences of intrusions imply that the strong post-rift magmatism in ZJNB was associated with the Hainan mantle plume arising from the core-mantle boundary.Furthermore,these forced folds could produce several types of hydrocarbon traps,due to accommodation through bending and uplift of the overlying rock and free surface,but it is critical to evaluate the effect of such emplacement when setting exploration targets.展开更多
The Mesoproterozoic Baoban Group is the oldest basement in Hainan Island and has played an important role in Columbia(Nuna)supercontinent reconstructions.The Mesoproterozoic granitic intrusions in the Baoban Group are...The Mesoproterozoic Baoban Group is the oldest basement in Hainan Island and has played an important role in Columbia(Nuna)supercontinent reconstructions.The Mesoproterozoic granitic intrusions in the Baoban Group are the most widely-exposed Precambrian magmatic rocks and are the key to understanding the tectonic settings of Hainan Island and its relationship with the South China Block and the Columbia supercontinent.New LA-ICP-MS zircon U-Pb dating on three mylonitic granite samples from the Tuwaishan and Baoban areas yield ages ranging from 1447 Ma to 1437 Ma,representing the absolute timing of the emplacement of the granitic intrusions.Combined with previously published geochronological data for rocks from the Baoban Group and regional mafic intrusions,it is concluded that the Baoban Group formed at 1460-1430 Ma,coeval with the emplacement of the granitic and mafic intrusions.New in-situ zircon LuHf isotope analyses for the three mylonitic granite samples yielded positiveε(t)values,ranging from+0.49 to+8.27,with model ages(T~C)ranging from 2181 Ma to 1687 Ma,suggesting that the granitic intrusions originated from a mixed source of Paleoproterozoic crust with juvenile crust.New zircon trace element data show characteristics of high Th/U values of 0.24-1.50,steep slopes from LREE to HREE and negative Pr,Eu anomalies with positive Ce,Sm anomalies,representing typical magmatic zircons formed in continental crust.Compared with available magmatic and detrital zircon ages from Precambrian rocks in the Cathaysia Block,Yangtze Block and western Laurentia,it is inferred that Hainan Island was separated from both the Cathaysia Block and the Yangtze Block,instead being connected with western Laurentia in the Columbia supercontinent.Considering the decreasing tendency of basin deposition time along the western margin of Laurentia,it is proposed that Hainan Island was located to the north or northwest of the Belt-Purcell Supergroup,along the western margin of Laurentia,during the breakup of the Columbia supercontinent.展开更多
Sandstone“injectite”intrusions are generally developed by the fluidization of weakly cemented sandstones and their subsequent injection into fractured reservoirs.In this work,a continuum coupled hydromechanical mode...Sandstone“injectite”intrusions are generally developed by the fluidization of weakly cemented sandstones and their subsequent injection into fractured reservoirs.In this work,a continuum coupled hydromechanical model TOUGH-FLAC3D is applied to simulate the discrete fracture network in large-scale sand injectite complexes.A sand production constitutive model is incorporated to consider the formation of sand through plastic deformation and its influence on evolution of fracture permeability.Overpressures in the fluidized sand slurry drives the injection with sand dikes intruded upwards,typically into previously low permeability“tight”mudstone formations.The contrast in poroelastic properties of the underlying weak sandstone and overlying injectite receptor directly affects the evolution of fracture aperture both during and after intrusion.Fluid drainage into the unconsolidated matrix may reduce the extent of fracture aperture growth,through the formation of shear bands.The results of this work have broad implications related to the emplacement of sandstone intrusions and subsequent hydrocarbon accumulation,maturation and then production.展开更多
1 Introduction After the Dongchuan Orogenic movement(Hudsonian Orogeny,ca.1800 Ma±),the tectonic basement layer of the continental crust on the Yangtze massif could have been formed.And then tectonic-magmatic emp...1 Introduction After the Dongchuan Orogenic movement(Hudsonian Orogeny,ca.1800 Ma±),the tectonic basement layer of the continental crust on the Yangtze massif could have been formed.And then tectonic-magmatic emplacement展开更多
Tectonic evolution and paleogeography of the two major continental blocks Fennoscandia and VolgoSarmatia during their docking to form the East European Craton(Baltica)at 1.8–1.7 Ga represent important‘puzzle
基金support from the National Natural Science Foundation of China (Grant No. 42276049)。
文摘The conventional view suggests that the subduction of the South China Sea plate beneath Luzon occurred due to the oceanic lithosphere’s high density,facilitating subduction initiation.However,before the South China Sea opened,a continental margin likely existed,meaning that Luzon was directly adjacent to the continental margin rather than the oceanic basin.This would make subduction initiation more challenging.Here,we propose a new model suggesting that during the formation of the South China Sea,extensive mafic magmatic underplating occurred along its continental margin.The high-density magmatic additions may have increased the overall density of the continental margin,potentially exceeding that of Luzon,thereby enabling subduction to proceed.
文摘The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as source rocks,reservoirs,seals,migration pathways,and trapping mechanisms.However,due to the limited number of wells drilled in the region,there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation.To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system,particularly source rock,an integrated geochemical and resistivity log analysis was carried out.The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents(TOC<1 wt%),kerogen yield(<1 Mg HC/g),and Hydrogen Index(<100 Mg HC/g),primarily composed of TypeⅢ(gas-prone)to TypeⅣ(inert)kerogens.These sediments have undergone varying levels of thermal maturity,ranging from post-mature(within Cretaceous),matured(in Paleocene)to immature(in Eocene)thermal states.The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration,resulting in a reduction of both organic matter(OM)content and source potential compared to the Eocene and Paleocene samples.This observation is consistent with the estimated paleotemperature(T)and resistivity log(ILD)along the depth profile,which have mapped local thermal alteration increasing from base Paleocene to Cretaceous.These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin.This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks.These intrusions pose a potential risk in petroleum exploration,especially when they intrude into matured source rock intervals.
基金financially supported by the second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0605)the National Natural Science Foundation of China(42371151)+3 种基金the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2023)the research grant of State Key Laboratory of Isotope Geochemistry(SKLaBIG-KF-22-05)the Natural Science Foundation of Gansu Province(23JRRA648)China Postdoctoral Science Foundation(2022M723358)。
文摘Downward transport of stratospheric air into the troposphere(identified as stratospheric intrusions)could potentially modify the radiation budget and chemical of the Earth's surface atmosphere.As the highest and largest plateau on earth,the Tibetan Plateau including the Himalayas couples to global climate,and has attracted widespread attention due to rapid warming and cryospheric shrinking.Previous studies recognized strong stratospheric intrusions in the Himalayas but are poorly understood due to limited direct evidences and the complexity of the meteorological dynamics of the third pole.Cosmogenic^(35)S is a radioactive isotope predominately produced in the lower stratosphere and has been demonstrated as a sensitive chemical tracer to detect stratospherically sourced air mass in the planetary boundary layer.Here,we report 6-month(April–September 2018)observation of^(35)S in atmospheric sulfate aerosols(^(35)SO_(4)^(2-))collected from a remote site in the Himalayas to reveal the stratospheric intrusion phenomenon as well as its potential impacts in this region.Throughout the sampling campaign,the^(35)SO_(4)^(2-)concentrations show an average of 1,070±980 atoms/m^(3).In springtime,the average is 1,620±730 atoms/m^(3),significantly higher than the global existing data measured so far.The significant enrichments of^(35)SO_(4)^(2-)measured in this study verified the hypothesis that the Himalayas is a global hot spot of stratospheric intrusions,especially during the springtime as a consequence of its unique geology and atmospheric couplings.In combined with the ancillary evidences,e.g.,oxygen-17 anomaly in sulfate and modeling results,we found that the stratospheric intrusions have a profound impact on the surface ozone concentrations over the study region,and potentially have the ability to constrain how the mechanisms of sulfate oxidation are affected by a change in plateau atmospheric properties and conditions.This study provides new observational constraints on stratospheric intrusions in the Himalayas,which would further provide additional information for a deeper understanding on the environment and climatic changes over the Tibetan Plateau.
基金funded by grants from the National Key R&D Program of China (2016YFC0600403, 2017YFC0601206)the National Natural Science Foundation of China (41872063, 41930215, 41520104003, 41888101)+1 种基金the Key Research Program of Frontier Sciences, CAS (QYZDJ-SSWSYS012)the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (CUGL170404, CUG160232)
文摘The Central Asian Orogenic Belt(CAOB) resulted from accretion during the Paleozoic subduction of the PaleoAsian Ocean. The Xilinhot area in Inner Mongolia is located in the northern subduction zone of the central-eastern CAOB and outcropped a large number of late Paleozoic mafic intrusions. The characteristics of magma source and tectonic setting of the mafic intrusions and their response to the closure process of the Paleo-Asian Ocean are still controversial. This study presents LA-ICPMS zircon U-Pb ages and geochemical features of mafic intrusions in the Xilinhot area to constrain the northward subduction of the Paleo-Asian Ocean. The mafic intrusions consist of gabbro, hornblende gabbro, and diabase. Their intrusion times can be divided into three stages of 326-321 Ma, 276 Ma and 254 Ma by zircon U-Pb ages. The first two stages of the 326-276 Ma intrusions mostly originated from subduction-modified continental lithospheric mantle sources that underwent a variable degree partial melting(5-30%), recording the subduction of oceanic crust. The third stage of the 254 Ma mafic rocks also show arc-related features. The primary magma compositions calculated by PRIMELT2 modeling on three samples of ~326 Ma and two samples of ~254 Ma show that these mafic samples are characterized by a variable range in SiO2(47.51-51.47 wt%), Al2O3(11.46-15.55 wt%), ΣFeO(8.27-9.61 wt%), MgO(13.01-15.18 wt%) and CaO(9.13-11.67 wt%), consisting with the features between enriched mantle and lower continental crust. The source mantle melting of mafic intrusions occurred under temperatures of 1302-1351°C and pressures of 0.92-1.30 GPa. The magmatic processes occurred near the crust-mantle boundary at about 33-45 km underground. Combined with previous studies, it is concluded that Carboniferous to early Permian(~326-275 Ma) northward subduction of the Paleo-Asian oceanic crust led to the formation of the mafic magmatism in the Baolidao arc zone. The whole region had entered the collision environment at ~254 Ma, but with subduction-related environments locally. The final collision between the North China craton and the South Mongolian microcontinent may have lasted until ca. 230 Ma.
基金supported by the National Basic Research Program of China(2009CB421002)National Natural Science Foundation of China(Grant No.40473008,40273020,40572036)+1 种基金Program for New Century Excellent Talents in University(Grant No.NCET-04-0728)Project(B07011)and PCSIRT.
文摘There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province （LIP）; namely, small ultramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element （PGE）-bearing sulfide deposits and large mafic layered intrusions that host giant Ti-V magnetite deposits in the Panxi region. However, except for their coeval ages, the genetic relations between the ore-bearing intrusions and extrusive rocks are poorly understood. Phase equilibria analysis （Q-PI-OI-Opx-Cpx system） has been carried out to elucidate whether ore-bearing Panzhihua, Xinjie and Limahe intrusions are co-magmatic with the picrites and flood basalts （including high-Ti, low-Ti and alkali basalts）, respectively. In this system, the parental magma can be classified as silica-undersaturated olivine basalt and silica-saturated tholeiite. The equivalents of the parental magma of the Xinjie and Limahe peridotites and picrites and low-Ti basalts are silica-undersaturated, whereas the Limahe gabbro-diorites and high-Ti basalts are silica-saturated. In contrast, the Panzhihua intrusion appears to be alkali character. Phase equilibria relations clearly show that the magmas that formed the Panzhihua intrusion and high-Ti basalts cannot be co-magmatic as there is no way to derive one liquid from another by fractional crystallization. On the other hand, the Panzhihua intrusion appears to be related to Permian alkali intrusions in the region, but does not appear to be related to the alkali basalts recognized in the Longzhoushan lava stratigraphy. Comparably, the Limahe intrusion appears to be a genetic relation to the picrites, whereas the Xinjie intrusion may be genetically related to be low-Ti basalts. Additionally, the gabbro-diorites and peridotites of the Limahe intrusion are not co-magmatic, and the former appears to be derived liquid from high-Ti basalts.
基金supported by the Key Laboratory of Xinjiang Uygur Autonomous Region (No. 2016D03002)the National Natural Science Foundation of China (No. 41562010)+1 种基金the China Postdoctoral Science Foundation (No. 2017M613257)Doctoral Scientific Research Foundation of Xinjiang University (No. BS100127)
文摘Late Paleozoic mafic-intermediate intrusions are widespread in the central Tianshan belt, but their tectonic settings remain controversial. Petrogenesis of these intrusions can provide insights into the tectonic evolution of the belt and its adjacent areas. This study presents new whole-rock geochemical and zircon U-Pb geochronology and Hf isotopic data for the Yaxi diorite and Qianzishan gabbro on the northern margin of the central Tianshan(NW China). Zircon U-Pb dating yielded the magma crystallization ages of 313±4 and 295±4 Ma for the Yaxi diorite and Qianzishan gabbro, respectively. They have lower Mg# values, Ni and Cr contents than typical mantle-derived primary melt, with negative correlations between MgO, TFeO and SiO2 contents, indicating clinopyroxene and olivine fractionation during magma evolution. They are characterized by enrichment of large ion lithophile elements(e.g., Rb, Ba and Sr) and depletion of high field strength elements(e.g., Nb, Ta and Ti) with high Ba/Th and Rb/Y, suggesting that their mantle sources had been metasomatized by slab-derived fluids. In addition, the Qianzishan gabbro has high Al2 O3 contents(19.54 wt.%–20.88 wt.%) and positive Eu anomalies(Eu/Eu*=1.09–1.42), which can be attributed to accumulation of plagioclase. Geochemical and zircon Hf isotopic compositions reveal that both the Yaxi diorite and Qianzishan gabbro were derived from depleted lithospheric mantle in the spinel stability field with insignificant crustal contamination. In association with previous investigations, we suggest that the Yaxi and Qianzishan intrusions were emplaced in a subduction-related environment, which means that the subduction of the Junggar Ocean lasted at least to the earliest Permian.
文摘Many important metal resources, such as Ni （Cu, Co）, PGE, exist in magmatic sulfide deposits, are a hot spot in geological research. We divide the magmatic sulphide deposits in China into four types according to their tectonic setting, intruding mode, ore deposit mode, main metallogenic elements. The four types are as follows： （1） Small-intrusion deposits in paleo-continent; （2） Smallintrusion deposits in continental flood basalt; （3） Small-intrusion deposits in orogenic belt; and （4） The deposits associated with ophiolites. On the basis of the classification, we put forward that the main magmatic metallogenic type in China is small-intrusion metallogeny, and describe its characteristics from small intrusions related concept, three geologic settings, three volcanic-intrusive assemblages and metallogenic key factors. According to the experiences of prospecting at home and abroad, we point out that there is big potential in prospecting small-intrusion deposits, which need further study. At last, we indicate that small-intrusion metallogeny not only widely distributes in mafic-ultramafic intrusions, but also has an important economic value and scientific significance in intermediate-acid intrusions.
基金funded by the projects of China Geological Survey (Grant Nos. DD20160123 (DD-16-049, D1522), 12120114020901, 1212011220928 and 1212011121075)
文摘The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.
基金financially supported by the National Natural Science Foundation of China(Grant No.41872056)。
文摘The northern margin of the North China Craton(NCC)contains widespread Permian magmatic rocks,but the origin of these rocks remains controversial.This uncertainty hampers us from better understanding of tectonic framework and evolution of the eastern Paleo-Asian Ocean,particularly with respect to its final-stage subduction and closure time.To address these questions,this study presents petrological,zircon U-Pb geochronological,whole-rock geochemical and in situ zircon Hf isotopic data for these Permian mafic intrusions in the northern margin of the NCC.Precise zircon U-Pb dating results indicate that these mafic intrusions were emplaced in the Middle Permian(ca.260 Ma).Geochemically,the studied mafic intrusions have high MgO and transition metals element contents,with high Mg^(#) values,indicating a mantle origin.These mafic intrusions are characterized by enrichments in large ion lithophile elements(LILEs;e.g.,Rb,Ba,and K)and light rare earth elements(LREEs),and depletions in high field strength elements(HFSEs;e.g.,Nb,Ta,and Ti)and heavy rare earth elements(HREEs),indicating that they were formed in a subduction-related setting.These geochemical features,together with zircon ε_(Hf)(t)values(-1.1 to+11.2),indicate that their parental magmas were derived from partial melting of heterogeneous mantle wedge metasomatized by subduction-related fluids,with the contributions of slab sediments.The studied mafic intrusions also show wide range of major and trace elements contents,and variable Mg^(#) values,Eu and Sr anomalies,suggesting that their parental magmas had undergone variable degrees of fractional crystallization.Together with the E-W trending Permian continental arc along the northern margin of the NCC,we confirm that the generation of the Middle Permian mafic intrusions was related to southward subduction of the Paleo-Asian oceanic lithosphere beneath the NCC and the Paleo-Asian Ocean had not closed prior to the Middle Permian.
基金funded by the National Key Research and Development Program of China 'Deep Structure and Ore-forming Process of Main Mineralization system in Tibetan Orogen'(NO.2016YFC0600300)the National Basic Research Program of China(NO.2011CB403104)+1 种基金the China Geological Survey(NO.12120113037901)the National Nature Science Foundation of China (NO.41320104004)
文摘A mosaic of terranes or blocks and associated Late Paleozoic to Mesozoic sutures are characteristics of the north Sanjiang orogenic belt （NSOB）. A detailed field study and sampling across the three magmatic belts in north Sanjiang orogenic belt, which are the Jomda-Weixi magmatic belt, the Yidun magmatic belt and the Northeast Lhasa magmatic belt, yield abundant data that demonstrate multiphase magmatism took place during the late Paleozoic to early Mesozoic. 9 new zircon LA-ICP-MS U-Pb ages and 160 published geochronological data have identified five continuous episodes of magma activities in the NSOB from the Late Paleozoic to Mesozoic： the Late Permian to Early Triassic （c. 261-230 Ma）; the Middle to Late Triassic （c. 229-210 Ma）; the Early to Middle Jurassic （c. 206-165 Ma）; the Early Cretaceous （c. 138-110 Ma） and the Late Cretaceous （c. 103-75 Ma）. 105 new and 830 published geochemical data reveal that the intrusive rocks in different episodes have distinct geochemical compositions. The Late Permian to Early Triassic intrusive rocks are all distributed in the Jomda-Weixi magmatic belt, showing arc-like characteristics; the Middle to Late Triassic intrusive rocks widely distributed in both Jomda-Weixi and Yidun magmatic belts, also demonstrating volcanic-arc granite features; the Early to Middle Jurassic intrusive rocks are mostly exposed in the easternmost Yidun magmatic belt and scattered in the westernmost Yangtza Block along the Garze-Litang suture, showing the properties of syn-collisional granite; nearly all the Early Cretaceous intrusive rocks distributed in the NE Lhasa magmatic belt along Bangong suture, exhibiting both arc-like and syn-collision-like characteristics; and the Late Cretaceous intrusive rocks mainly exposed in the westernmost Yidun magmatic belt, with A-type granite features. These suggest that the co-collision related magmatism in Indosinian period developed in the central and eastern parts of NSOB while the Yanshan period co-collision related magmatism mainly occurred in the west area. In detail, the earliest magmatism developed in late Permian to Triassic and formed the Jomda-Wei magmatic belt, then magmatic activity migrated eastwards and westwards, forming the Yidun magmatic bellt, the magmatism weakend at the end of late Triassic, until the explosure of the magmatic activity occurred in early Cretaceous in the west NSOB, forming the NE Lhasa magmatic belt. Then the magmatism migrated eastwards and made an impact on the within-plate magmatism in Yidun magmatic belt in late Cretaceous.
基金supported by the National Science Foundation of China (NSFC) project(41203039)the innovation team of ore-forming dynamics and prediction of concealed deposits, KMUST(2008)
文摘The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite porphyry. The K20 content of majority of these rocks is greater than 3%, and, in the K20-SiO2 diagram, all the samples fall into the high-K calc-alkaline to shoshonitic fields. They are enriched in light rare earth elements （LREEs） and depleted in heavy rare earth elements （HREEs; LaN/YbN = 14.3-21.2）, and show slightly negative Eu anomalies （6Eu = 0.77-1.00）. These rocks have high K, Rb, Sr, and Ba contents; moderate to high enrichment of compatible elements （Cr = 36.7-79.9 ppm, Co = 9.6-16.4 ppm, and MgO = 2.2%-3.4%）; low Nb, Ta, and Ti contents, and characteristic of low high field strength elements（HFSEs） versus incompatible elements ratios （Nb/Th = 0.75, Nb/La = 0.34） and incompatible elements ratios （Nb/U = 3.0 and Ce/Pb = 5.1, Ba/Rb = 12.0）. These rocks exhibit restricted Sr and Nd isotopic compositions, with （87Sr/S6Sr）i values ranging from 0.7044 to 0.7069 and ENd（t） values from -2.8 to -2.2. The Sr-Nd isotope systematic and specific trace element ratios suggest that Langdu high-K calc-alkaline intrusive rocks derived from a metasomatized mantle source. The unique geochemical feature of intrusive rocks can be modeled successfully using different members of a slightly enriched mantle, a slab-derived fluid, and terrigenous sediments. It can be inferred that the degree of partial melting and the presence of specific components are temporally related to the tectonic evolution of the Zhongdian island arc. Formation of these rocks can be explained by the various degrees of melting within an ascending region of the slightly enriched mantle, triggered by the subduction of the Garz^--Litang ocean, and an interaction between the slab-derived fluid and the terrigenous sediments.
基金The National Natural Science Foundation of China under contract No.40890152the National Basic Research Program of China under contract No.2012CB417401
文摘The existing high-resolution hydrographic data in the western tropical Pacilit; Ocean are used to explore the spatial distribution and primary characteristics of thermohaline intrusions in the thermocline. Statistics show that the vertical scales of intrusions are 20-40 m in the upper thermocline （22.0-26.0δ0） and 40-80 m in the lower thermocline （26.0-27.2δ0）. In the upper thermocline, the most intensive intrusions exist at the equatorial front （EF） where north/sonth Pacilic water masses converge, anti Ihe westward spreading of the north Pacilic tropical waler （NPTW） in the Philippines Sea also produces patches of intrusions surrounding its high-salinity tongue. In the lower thermocline, intrusions are also strong at the tropical front （TF） which is the boundary between the north Pacilic subtropical/tropical waters. At the bottom of the thermocline （at about 27.0δ0）, intrusions mainly exist near the western boundary, which are produced by intermediate water convergence through the advection of subthermocline western boundary Ilows. Most strikingly a ＂C＂-shape distribution of intrusions at around 26.4δ0 is revealed, covering the vicinity of the EF the TE and the Mindanao Current （MC）, i.e., tile western boundary pathway ol the norlh Pacilic subtrnpical cell （STC）. Synoptic section analysis reveals that intrusions are more prominent on the warm/sally flank ot the fronts, implying more cross-front tongues of cold/fresh water. Among the intrusions, those at the EF are of best lateral coherence which implies a unique driving mechanism involving near-inertial velocity perturbations near the equator.
文摘Baddeleyite（ZrO2）is today recognized as a key mineral for dating the emplacement of mantle-derived rocks such as gabbros,alkaline（Si-poor）rocks and dolerite dykes and sills,but also in hydrothermally-driven
基金financially supported by the Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0801)the National Natural Science Foundation of China (NSFC programs 41772088, 41773042 and 41773043)the Geological Survey Project (DD20190001).
文摘1.Objectives The porphyry copper deposits (PCD) are usually hosted in a multistage intrusive complex but only causallyrelated tospecific magma of high oxidation state and water content. The copper enrichment of the porphyry system is caused by accumulation during magmatic differentiation (Hou ZQ et al., 2015). Thus, study on magmatic evolution and Cu mineralization process is important for understanding the formation of PCD.
基金supported by the National Key Research and Development Project(2019YFA0708500)the National Natural Science Foundation of China(No.42202170 and U20B6001)。
文摘The transportation of magma in sedimentary basins often occurs through extensive dyke-sill networks.The role of sills on the plumbing system in rifted margins and the impact of sills on hydrocarbon reservoirs of prospective sedimentary basins has long been an area of great industrial interest and scientific debate.Based on 2D seismic reflection,we present data on how the sills emplaced to form a magmatic plumbing system of the volcanic system for the Zhongjiannan Basin(ZJNB).The results show that sixty-nine sills and fourteen forced folds have been identified.The distribution and geometry of the sills suggest that magma flowed from west to east and then ascended to near the surface.The onlap relationship of the forced folds indicates that the timing of magmatic activities can be constrained at ca.0.2 Ma.The spatial and temporal occurrences of intrusions imply that the strong post-rift magmatism in ZJNB was associated with the Hainan mantle plume arising from the core-mantle boundary.Furthermore,these forced folds could produce several types of hydrocarbon traps,due to accommodation through bending and uplift of the overlying rock and free surface,but it is critical to evaluate the effect of such emplacement when setting exploration targets.
基金funded by the Chinese Geological Survey Program(Grant Nos.DD20160035,DD20190047)the National Nonprofit Institute Research Grant of IGGE(AS2022P03)the Chinese Scholarship Council(File No.201606400032)Scholarship to Liu Yuheng。
文摘The Mesoproterozoic Baoban Group is the oldest basement in Hainan Island and has played an important role in Columbia(Nuna)supercontinent reconstructions.The Mesoproterozoic granitic intrusions in the Baoban Group are the most widely-exposed Precambrian magmatic rocks and are the key to understanding the tectonic settings of Hainan Island and its relationship with the South China Block and the Columbia supercontinent.New LA-ICP-MS zircon U-Pb dating on three mylonitic granite samples from the Tuwaishan and Baoban areas yield ages ranging from 1447 Ma to 1437 Ma,representing the absolute timing of the emplacement of the granitic intrusions.Combined with previously published geochronological data for rocks from the Baoban Group and regional mafic intrusions,it is concluded that the Baoban Group formed at 1460-1430 Ma,coeval with the emplacement of the granitic and mafic intrusions.New in-situ zircon LuHf isotope analyses for the three mylonitic granite samples yielded positiveε(t)values,ranging from+0.49 to+8.27,with model ages(T~C)ranging from 2181 Ma to 1687 Ma,suggesting that the granitic intrusions originated from a mixed source of Paleoproterozoic crust with juvenile crust.New zircon trace element data show characteristics of high Th/U values of 0.24-1.50,steep slopes from LREE to HREE and negative Pr,Eu anomalies with positive Ce,Sm anomalies,representing typical magmatic zircons formed in continental crust.Compared with available magmatic and detrital zircon ages from Precambrian rocks in the Cathaysia Block,Yangtze Block and western Laurentia,it is inferred that Hainan Island was separated from both the Cathaysia Block and the Yangtze Block,instead being connected with western Laurentia in the Columbia supercontinent.Considering the decreasing tendency of basin deposition time along the western margin of Laurentia,it is proposed that Hainan Island was located to the north or northwest of the Belt-Purcell Supergroup,along the western margin of Laurentia,during the breakup of the Columbia supercontinent.
基金the financial support from the Laboratory of Coal Resources and Safe Mining(China University of Mining and Technology,Beijing)(Grant No.SKLCRSM16KFC01)。
文摘Sandstone“injectite”intrusions are generally developed by the fluidization of weakly cemented sandstones and their subsequent injection into fractured reservoirs.In this work,a continuum coupled hydromechanical model TOUGH-FLAC3D is applied to simulate the discrete fracture network in large-scale sand injectite complexes.A sand production constitutive model is incorporated to consider the formation of sand through plastic deformation and its influence on evolution of fracture permeability.Overpressures in the fluidized sand slurry drives the injection with sand dikes intruded upwards,typically into previously low permeability“tight”mudstone formations.The contrast in poroelastic properties of the underlying weak sandstone and overlying injectite receptor directly affects the evolution of fracture aperture both during and after intrusion.Fluid drainage into the unconsolidated matrix may reduce the extent of fracture aperture growth,through the formation of shear bands.The results of this work have broad implications related to the emplacement of sandstone intrusions and subsequent hydrocarbon accumulation,maturation and then production.
基金financial support by The Researchon Occurrence State of Element and Tectonic Lithofacies Mapping Technique for the Iron -Oxide Copper Gold Deposits (2011EG115022, 2013EG115018)
文摘1 Introduction After the Dongchuan Orogenic movement(Hudsonian Orogeny,ca.1800 Ma±),the tectonic basement layer of the continental crust on the Yangtze massif could have been formed.And then tectonic-magmatic emplacement
基金funded by grant 14-05-00731 from the Russian Foundation of Basic Research
文摘Tectonic evolution and paleogeography of the two major continental blocks Fennoscandia and VolgoSarmatia during their docking to form the East European Craton(Baltica)at 1.8–1.7 Ga represent important‘puzzle
