Eight dissolution models of calcium apatites(both fluorapatite and hydroxyapatite) in acids were drawn from the published literature,analyzed and discussed.Major limitations and drawbacks of the models were conversed ...Eight dissolution models of calcium apatites(both fluorapatite and hydroxyapatite) in acids were drawn from the published literature,analyzed and discussed.Major limitations and drawbacks of the models were conversed in details.The models were shown to deal with different aspects of apatite dissolution phenomenon and none of them was able to describe the dissolution process in general.Therefore,an attempt to combine the findings obtained by different researchers was performed which resulted in creation of the general description of apatite dissolution in acids.For this purpose,eight dissolution models were assumed to complement each other and provide the correct description of the specific aspects of apatite dissolution.The general description considers all possible dissolution stages involved and points out to some missing and unclear phenomena to be experimentally studied and verified in future.This creates a new methodological approach to investigate reaction mechanisms based on sets of affine data,obtained by various research groups under dissimilar experimental conditions.展开更多
1 Introduction Studies of marine sedimentary phosphate rock have lasted decades,scholars proposed some standpoints about mineralization,however,the genesis of mineral deposits remains to be a controversial question(Sh...1 Introduction Studies of marine sedimentary phosphate rock have lasted decades,scholars proposed some standpoints about mineralization,however,the genesis of mineral deposits remains to be a controversial question(She et al.,2013).There are many viewpoints of mineralization about the Doushantuo phosphorites,Central Guizhou,including biological mineralization(Mi et al.,2010;Shi et al.,2005),展开更多
Apatites occurring in sedimentary rocks are carbonate fluorapatites (C-F apatites) with differentCO_2 contents. During diagenesis. the CO_2 in the C-F apatites gradually decreased with the increasing strengthof diagen...Apatites occurring in sedimentary rocks are carbonate fluorapatites (C-F apatites) with differentCO_2 contents. During diagenesis. the CO_2 in the C-F apatites gradually decreased with the increasing strengthof diagenesis. resulting in the systematic changes in refractive index. specific gravity, cell parameters and crystalchemistry of apatites. On the basis of X-ray diffraction and IR spectroscopic analyses, the author proposes twoparameters for determining diagenetic stages. i.e.. the crystallinity index (CR) and sharpness index (SH). Thesetwo parameters serve as new criteria for the determination. which due to the common existence of phosphorousnodules and bands and argillo-crystalline cement in sedimentary rocks, most likely have wide prospects for ap-plication.展开更多
The links between the adakitic rocks and Cu-Au mineralization have long been argued.This study investigates petrogenesis and its link to mineralization potential by a series of in-situ geochronological and geochemical...The links between the adakitic rocks and Cu-Au mineralization have long been argued.This study investigates petrogenesis and its link to mineralization potential by a series of in-situ geochronological and geochemical signatures of apatite and zircon in three ore-related intrusions and one-barren intrusion in the Middle-Lower Yangtze River Metallogenic Belt(MLYRB).Zircon U-Pb dating yield ages of 139–143 Ma and 121 Ma for the ore-related and ore-barren intrusions,respectively.The ore-related rocks have higher apatite Sr/Y(1.57–9.69),(La/Yb)_(N)(16.7–159.5),andδEu(0.45–0.74)than the ore-barren rocks of 0.57–1.02,19.3–24.1 and 0.40–0.45,respectively,indicating the former has an adakitic affinity,while the latter has a non-adakitic affinity.The ore-related rocks have enriched zircon Hf isotopes withε_(Hf)(t)values of-15.9 to-5.5 and T_(DMC)ages of 2408–1655 Ma and apatite Sr-Nd isotopes,indicating that the ore-related magmas were mainly originated from partial melting of subducted oceanic crust.The orebarren rocks have higherε_(Hf)(t)values of-6.6 to-4.6 and lower T_(DMC)ages of 1598–1469 Ma and apatite Sr-Nd isotopes,indicating a lithospheric mantle source.The ore-related rocks have higher oxygen fugacity of mean∆FMQ+2.00 and X_(F)/X_(OH)of 8.36–175 than the ore-barren rocks of mean∆FMQ+1.43 and3.72–4.96.It was inferred that magma source,water content,and oxygen fugacity emerge as critical factors governing the regional Cu-Au mineralization potential.展开更多
The global reliance on phosphate rock for agriculture and other industries,coupled with chemical regulations in developed countries,has driven the search for green alternatives in apatite flotation.This review investi...The global reliance on phosphate rock for agriculture and other industries,coupled with chemical regulations in developed countries,has driven the search for green alternatives in apatite flotation.This review investigates eco-friendly collectors’effectiveness in promoting sustainable mineral processing,guiding future alternatives to traditional reagents.The manuscript discussed the surface properties of apatite and its interaction with eco-friendly collectors,assessing existing fundamental studies.This study sought to:(1)define,organize,and classify“eco-friendly”collectors;(2)evaluate their effect in IEP and contact angle;(3)provide a better understanding of the adsorption behavior of the different fatty acid chains into apatite surface;(4)assess their ability to reversely and directly float apatite;(5)address gaps to achieve selectivity and process optimization.Outcomes demonstrated that fatty acids are largely applied,but other renewable sources of these reagents have been promisingly evaluated.In addition,other natural reagents have been tested,and new green synthetics have demonstrated synergistic effects when combined with fatty acids,yielding significant improvements in grade and recovery.However,collector effectiveness varies with ore characteristics,like particle size and surface properties,which remain underexplored.Future research should design tailored collectors that align with mineralogical differences to enhance selectivity.展开更多
The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is si...The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.展开更多
Lithium is a critical strategic metal with signifi-cant reserves in pegmatites,serving as the primary source for global Li production.Apatite has attracted increasing attention as an indicator in petrogenesis studies ...Lithium is a critical strategic metal with signifi-cant reserves in pegmatites,serving as the primary source for global Li production.Apatite has attracted increasing attention as an indicator in petrogenesis studies and for the exploration of ore deposits.In this study,we investigated the volatile compositions and major and trace elements of apatite from the Qiongjiagang pegmatite-type lithium deposit in Himalaya.Apatite derived from spodumene pegmatite exhibits relatively constant and high total rare earth element(ΣREE+Y)concentrations,ranging from 5899 to 8540 ppm.In contrast,apatite in barren pegmatite displays evidently lower(ΣREE+Y)concentrations,varying between 1345 and 3095 ppm.The REE patterns of apatite in spodumene pegmatite generally exhibit a flat shape[(La/Yb)N=1.55-2.15)],with distinctively negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.14-0.22),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.03-1.13),and low Y/Ho ratios(28-30).By contrast,apatite in barren pegmatite shows middle rare earth element(MREE)-depleted downward-convex patterns[(La/Yb)N=1.99-20.4)],strongly negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.01-0.14),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.10-1.24),and high Y/Ho ratios(30-55,with an average of 50).Overall,the high concentrations ofΣREE(and Y)and low Th/U and Y/Ho ratios can serve as diagnostic indicators to distinguish apatite in spodumene pegmatite from that in barren pegmatite.Furthermore,the flat REE pattern may represent a common feature of apatite from lithium deposits.Differences in the Ce and Eu anomalies between apatite from these two kinds of pegmatites likely reflect formation under different redox conditions.Consequently,based on calculations derived from apatite volatile compositions,the melt associated with spodumene pegmatite may contain higher water content compared to that of the barren one.Therefore,the mineralized pegmatite system may incorporate substantial amounts of H_(2)O-rich fluids,which play a crucial role in lithium mineralization.展开更多
The Triassic granitoids and associated diorites in the Qinling orogenic belt reveal critical evidence of crust-mantle interaction during the terminal collision between the North China and Yangtze Blocks.This study pre...The Triassic granitoids and associated diorites in the Qinling orogenic belt reveal critical evidence of crust-mantle interaction during the terminal collision between the North China and Yangtze Blocks.This study presents new constraints from zircon U-Pb age,Lu-Hf isotopes,and amphibole-plagioclase-apatite geochemistry for the Maoerliang diorite in the Foping area.Zircon U-Pb dating yields a crystallization age of 212±2.8 Ma,withεHf(t)values ranging from−8.6 to+3.0 and corresponding twostage Hf model ages(T_(DM2))of 886-1479 Ma,indicative of derivation from an evolved lithospheric mantle source.Petrogenetic indicators reveal a mantle affinity:amphiboles exhibit high MgO(9.8-11.2 wt%)and elevated Nb/Ta ratios(14.3-18.1),while apatites display F-rich(2.1-2.8 wt%)and Cl-poor(0.08-0.15 wt%)characteristics.Thermobarometric calculations based on amphibole chemistry constrain crystallization conditions of 805-866℃and 211-383 MPa,corresponding to mid-crustal emplacement depths(8-14 km).Both amphibole and zircon indicate elevated oxygen fugacity(ΔNNO=−4.08 to−3.71;ΔFMQ=−1.14 to+3.96)and hydrous magma conditions(H_(2)O=4.22-4.94 wt%).Late-stage plagioclase crystallization(An21-26.5)reflects prolonged fractional crystallization in a hydrous dioritic magma.These diagnostic features-mantle-derived signatures,high f O_(2),and hydrous nature-exhibit remarkable convergence with gold-mineralized granites in the East Qinling.Our findings suggest that Triassic dioritic magmatism may have played an underappreciated role in facilitating gold enrichment processes within the South Qinling metallogenic belt.展开更多
Detrital zircon and apatite U-Pb-Hf isotope and trace element analyses of the late Mesoproterozoic to early Neoproterozoic strata in southern Jilin provide detailed information on the sediment provenance and tectonic ...Detrital zircon and apatite U-Pb-Hf isotope and trace element analyses of the late Mesoproterozoic to early Neoproterozoic strata in southern Jilin provide detailed information on the sediment provenance and tectonic setting of the northeastern margin of the North China Craton(NCC).Here,we present U-Pb and Lu-Hf analyses of 712 detrital zircons,and U-Pb analyses of 347 detrital apatites from the Baifangzi,Diaoyutai and Qiaotou formations.The Baifangzi and Diaoyutai formations are dominated by Neoarchean(2.5-2.6 Ga)and Paleoproterozoic(1.8-1.9 Ga)zircons,indicating a predominant NCC provenance.The Qiaotou Formation is dominated by Mesoproterozoic(1.5-1.7 Ga and 1.1-1.3 Ga)zircons with mainly positiveεHf(t)values,which are similar to those from eastern Laurentia,implying a significant provenance transition.The detrital apatite age spectra of the Baifangzi and Diaoyutai Formations show major populations at 1.8-1.9 Ga and 1.1-1.3 Ga.Based on their trace element compositions,the Mesoproterozoic apatites were mainly sourced from metamorphic rocks,indicating regional metamorphism occurred in the NCC during 1.1-1.3 Ga.Combining these data with regional studies,we propose that the NCC was adjacent to eastern Laurentia during the assembly of the Rodinia supercontinent.展开更多
A set of ultramafic-mafic-felsic rock assemblages was discovered in the Long-shenggeng area of the eastern part of the East Kunlun orogenic belt.Petrography,chronology and whole-rock geochemistry were conducted on thi...A set of ultramafic-mafic-felsic rock assemblages was discovered in the Long-shenggeng area of the eastern part of the East Kunlun orogenic belt.Petrography,chronology and whole-rock geochemistry were conducted on this set of intrusive rock assemblages.U-Pb dating of apatite shows that the lherzolite formed at 492±5 Ma,the granite at 473±6 Ma,and the diabase at 260±14 Ma,respectively.The lherzolites belong to a supra-subduction zone type(SSZ-type)ophiolite component above a subduction zone;the granites formed in an ocean-continent subduction setting;and the diabases represent products of partial melting of an asthenospheric mantle at shallow depth.The East Kunlun orogenic belt features the East Kunzhong and Buqingshan-Animaqing ophiolitic mélange belts,with the latter representing remnants of the Proto-Tethys Ocean.The Late Cambrian lherzolites and granites in the Longshenggeng area were magmatic products of the back-arc ocean basin and island arc formed during the northward subduction of the Proto-Tethys Ocean.Subsequently,extensive island arc magmatism occurred from the Late Permian to Middle Triassic,driven by the northward subduction of the Paleo-Tethys Ocean beneath the East Kunlun Block.The diabase may have formed during the transition from subduction to post-collisional extension.展开更多
Passive-roof duplexes accommodate shortening at the mountain front of many fold-and-thrust belts worldwide.These structures typically manifest at the surface by hinterland-verging backthrusts that decouple thin-skinne...Passive-roof duplexes accommodate shortening at the mountain front of many fold-and-thrust belts worldwide.These structures typically manifest at the surface by hinterland-verging backthrusts that decouple thin-skinned thrust sheets from underlying foreland-verging duplexes.Although the main fac-tors controlling the development of passive-roof duplexes have mostly been identified,some of their intrinsic characteristics are still poorly defined.These relate to their spatio-temporal relationships to thrust faults located further inland in orogens,and their ability to transport younger rocks over older ones.This study explores these issues in the Casentino-Romagna axial sector of the Northern Apennines,which expose regional forethrusts and backthrusts.Detailed field mapping and analysis of superposed tectonic structures were integrated with apatite fission-track dating for constraining the tim-ing of rock exhumation and correlated tectonic events.Collectively,the results have allowed us to inter-pret the evolution of the study area in terms of two main deformation stages.Specifically,a first,long phase(D_(1))progressed from NE-directed,in-sequence thrusting(∼18 to∼10-9 Ma)to late out-of-sequence thrusting(∼8-5 Ma).A successive deformation phase,that we refer to as D_(2)(∼4-2 Ma),con-sisted of backthrusts and associated folds that were ubiquitous and systematically overprinted onto the foreland-verging D_(1)structures.Such retrovergent structures identify a late deformation phase dom-inated by the development of passive-roof duplexes that propagated hinterlandward into the orogen up to beyond the primary watershed ridge.Orogen-scale processes controlled the evolution of forelandward D_(1)-phase thrusts,although late erosion could have played a major role by bringing the Apennine thrust wedge toward an undercritical state.The latter conditions could have contributed to keeping the out-of-sequence thrusts active,and eventually promoted the development of the D_(2)passive-roof duplexes.展开更多
The temporal and spatial evolution of the Ailao Shan-Red River(ASRR)fault zone,which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau,is crucial for analyzing ...The temporal and spatial evolution of the Ailao Shan-Red River(ASRR)fault zone,which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau,is crucial for analyzing the uplift and growth of the plateau.Based on the petrology and apatite fission track analysis,the tectonic history and active pattern of the ASRR fault zone since the middle Miocene are determined in this study.The ASRR fault zone exhibits 12-8Ma and 8-4 Ma rapid cooling phases since the middle Miocene.The 12-8 Ma and 8-4 Ma cooling may imply that the dextral movement of the ASRR fault zone presents a migration trend from northwest to southeast,accompanied by the weakening of the activity intensity,which is directly related to deformation processes,including extrusion boundary migration and active tectonic movements of the southeastern Tibetan Plateau,since the middle-late Miocene.展开更多
Fluorine(F)-enriched soils,resulting from geogenic processes or superimposed by anthropogenic activities,have raised significant concerns due to their phytotoxicity and potential threats to human health.Soils in centr...Fluorine(F)-enriched soils,resulting from geogenic processes or superimposed by anthropogenic activities,have raised significant concerns due to their phytotoxicity and potential threats to human health.Soils in central Guizhou Province exhibit F enrichment,with a mean F concentration of 1067 mg/kg.However,the associated human health risks and geochemical mechanisms driving F enrichment in these soils remain insufficiently understood.In areas with a natural geological background,the average concentrations of F in rice,vegetables,drinking water,and ambient air are 1.54 mg/kg,0.54 mg/kg,0.16 mg/L,and 0.29μg/m^(3),respectively.In contrast,samples collected near phosphorous chemical plants demonstrate elevated F concentrations:1.78 mg/kg in rice,1.53 mg/kg in vegetables,0.20 mg/L in drinking water,and 11.98μg/m^(3) in ambient air.Fluorine in soils was immobilized by apatite and clay minerals,and hardly transferred into water and crops.The fixation of F-by Ca^(2+)in water and by Fe/Al hydroxides and clay minerals in bottom sediment further reduces F concentrations in water.As a result,hazard quotient(HQ)values below 1.0 indicate negligible fluorine-related health risk in geological background regions.However,ambient air near phosphorous chemical plant exhibited a 41.3-fold increase in F concentration compared to geological background regions.Fluorine-laden emissions can be directly inhaled or deposited on vegetable leaves and orally ingested into human bodies.Improvement of F-rich waste gas disposal and restricted leafy vegetable cultivation are effective measures to reduce F health risks in phosphorous chemical plant regions.展开更多
Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and pha...Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and phase constitues, roughness, contact angle and apatite induction of the alkali-treated coatings were studied and compared. Scanning electron microscope(SEM) was applied to observe the morphologies, X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to detect the phase constitutes and chemical compositions, a surface topography profilometer was used to analyze the surface roughness, and contact angle was measured by liquid drop method. Alkali treatements result in the formation of Na2Ti6O13 and Na2Ti3O7 phase on the MAO coating, which leads to the increase of surface roughness and the decrease of contact angle. Experimental results showed that the apatite induction of the alkali-treated coatings was dependent on the applied alkali concentrations during treatments, and Na+concentration can promote the formation of apatite phase.展开更多
Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite...Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.展开更多
The Weishan REE deposit is located at the eastern part of North China Craton(NCC), western Shandong Province. The REE-bearing carbonatite occur as veins associated with aegirine syenite. LA-ICP-MS bastnaesite Th-Pb ag...The Weishan REE deposit is located at the eastern part of North China Craton(NCC), western Shandong Province. The REE-bearing carbonatite occur as veins associated with aegirine syenite. LA-ICP-MS bastnaesite Th-Pb ages(129 Ma) of the Weishan carbonatite show that the carbonatite formed contemporary with the aegirine syenite. Based on the petrographic and geochemical characteristics of calcite, the REEbearing carbonatite mainly consists of Generation-1 igneous calcite(G-1 calcite) with a small amount of Generation-2 hydrothermal calcite(G-2 calcite). Furthermore, the Weishan apatite is characterized by high Sr, LREE and low Y contents, and the carbonatite is rich in Sr, Ba and LREE contents. The δ^(13)Cv-PDB(-6.5‰ to -7.9‰) and δ^(13)OV-SMOW(8.48‰-9.67‰) values are similar to those of primary, mantlederived carbonatites. The above research supports that the carbonatite of the Weishan REE deposit is igneous carbonatite. Besides, the high Sr/Y, Th/U, Sr and Ba of the apatite indicate that the magma source of the Weishan REE deposit was enriched lithospheric mantle, which have suffered the fluid metasomatism. Taken together with the Mesozoic tectono-magmatic activities, the NW and NWW subduction of Izanagi plate along with lithosphere delamination and thinning of the North China plate support the formation of the Weishan REE deposit. Accordingly, the mineralization model of the Weishan REE deposit was concluded: The spatial-temporal relationships coupled with rare and trace element characteristics for both carbonatite and syenite suggest that the carbonatite melt was separated from the CO_2-rich silicate melt by liquid immiscibility. The G-1 calcites were crystallized from the carbonatite melt, which made the residual melt rich in rare earth elements. Due to the common origin of G-1 and G-2 calcites, the REE-rich magmatic hydrothermal was subsequently separated from the melt. After that, large numbers of rare earth minerals were produced from the magmatic hydrothermal stage.展开更多
The Qilian Shan lies along the northeastern edge of the Tibetan Plateau. To constrain its deformation history, we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediatel...The Qilian Shan lies along the northeastern edge of the Tibetan Plateau. To constrain its deformation history, we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediately north of the mountain range. Paleocurrent measurements, sandstone compositional data, and facies analysis of Cenozoic stratigraphic sections suggest that the Jiuxi Basin received sediments from the Altyn Tagh Range in the northwest, initially in the Oligocene （-33 Ma）, depositing the Huoshaogou Formation in the northern part of the basin. Later, the source area of the Jiuxi Basin changed to the Qilian Shan in the south during Late Oligocene （-27 Ma）, which led to the deposition of the Baiyanghe Formation. We suggest that uplift of the northern Qilian Shan induced by thrusting began no later than the Late Oligocene. Fission-track analysis of apatite from the Qilian Shan yields further information about the deformation history of the northern Qilain Shan and the Jiuxi Basin. It shows that a period of rapid cooling, interpreted as exhumation, initiated in the Oligocene. We suggest that this exhumation marked the initial uplift of the Qilian Shan resulting from the India-Asia collision.展开更多
The apatite fission track（AFT） ages and thermal modeling of the Longshoushan and deformation along the northern Hexi Corridor on the northern side of the Qinghai-Tibetan Plateau show that the Longshoushan along the ...The apatite fission track（AFT） ages and thermal modeling of the Longshoushan and deformation along the northern Hexi Corridor on the northern side of the Qinghai-Tibetan Plateau show that the Longshoushan along the northern corridor had experienced important multi-stage exhumations during the Late Mesozoic and Cenozoic. The AFT ages of 7 samples range from 31.9 Ma to 111.8 Ma.Thermal modeling of the AFT ages of the samples shows that the Longshoushan experienced significant exhumation during the Late Cretaceous to the Early Cenozoic（-130-25 Ma）. The Late Cretaceous exhumation of the Longshoushan may have resulted from the continuous compression between the Lhasa and Qiangtang blocks and the flat slab subduction of the Neo-Tethys oceanic plate, which affected wide regions across the Qinghai-Tibetan Plateau. During the Early Cenozoic, the Longshoushan still experienced exhumation, but this process was caused by the Indian-Eurasian collision. Since this time,the Longshoushan was in a stable stage for approximately 20 Ma and experienced erosion. Since -5 Ma,obvious tectonic deformation occurred along the entire northern Hexi Corridor, which has also been reported from the peripheral regions of the Qinghai-Tibetan Plateau, especially in the Qilianshan and northeastern margin of the plateau. The AFT ages and the Late Cenozoic deformation of the northern Hexi Corridor all indicate that the present northern boundary of the Qinghai-Tibetan Plateau is situated along the northern Hexi Corridor.展开更多
文摘Eight dissolution models of calcium apatites(both fluorapatite and hydroxyapatite) in acids were drawn from the published literature,analyzed and discussed.Major limitations and drawbacks of the models were conversed in details.The models were shown to deal with different aspects of apatite dissolution phenomenon and none of them was able to describe the dissolution process in general.Therefore,an attempt to combine the findings obtained by different researchers was performed which resulted in creation of the general description of apatite dissolution in acids.For this purpose,eight dissolution models were assumed to complement each other and provide the correct description of the specific aspects of apatite dissolution.The general description considers all possible dissolution stages involved and points out to some missing and unclear phenomena to be experimentally studied and verified in future.This creates a new methodological approach to investigate reaction mechanisms based on sets of affine data,obtained by various research groups under dissimilar experimental conditions.
文摘1 Introduction Studies of marine sedimentary phosphate rock have lasted decades,scholars proposed some standpoints about mineralization,however,the genesis of mineral deposits remains to be a controversial question(She et al.,2013).There are many viewpoints of mineralization about the Doushantuo phosphorites,Central Guizhou,including biological mineralization(Mi et al.,2010;Shi et al.,2005),
文摘Apatites occurring in sedimentary rocks are carbonate fluorapatites (C-F apatites) with differentCO_2 contents. During diagenesis. the CO_2 in the C-F apatites gradually decreased with the increasing strengthof diagenesis. resulting in the systematic changes in refractive index. specific gravity, cell parameters and crystalchemistry of apatites. On the basis of X-ray diffraction and IR spectroscopic analyses, the author proposes twoparameters for determining diagenetic stages. i.e.. the crystallinity index (CR) and sharpness index (SH). Thesetwo parameters serve as new criteria for the determination. which due to the common existence of phosphorousnodules and bands and argillo-crystalline cement in sedimentary rocks, most likely have wide prospects for ap-plication.
基金supported by the National Natural Science Foundation of China(42472117)the China Geological Survey Project(DD20230040)+1 种基金the Natural Science Foundation of Anhui Province(2108085MD133)the PI Project of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2020GD0802)。
文摘The links between the adakitic rocks and Cu-Au mineralization have long been argued.This study investigates petrogenesis and its link to mineralization potential by a series of in-situ geochronological and geochemical signatures of apatite and zircon in three ore-related intrusions and one-barren intrusion in the Middle-Lower Yangtze River Metallogenic Belt(MLYRB).Zircon U-Pb dating yield ages of 139–143 Ma and 121 Ma for the ore-related and ore-barren intrusions,respectively.The ore-related rocks have higher apatite Sr/Y(1.57–9.69),(La/Yb)_(N)(16.7–159.5),andδEu(0.45–0.74)than the ore-barren rocks of 0.57–1.02,19.3–24.1 and 0.40–0.45,respectively,indicating the former has an adakitic affinity,while the latter has a non-adakitic affinity.The ore-related rocks have enriched zircon Hf isotopes withε_(Hf)(t)values of-15.9 to-5.5 and T_(DMC)ages of 2408–1655 Ma and apatite Sr-Nd isotopes,indicating that the ore-related magmas were mainly originated from partial melting of subducted oceanic crust.The orebarren rocks have higherε_(Hf)(t)values of-6.6 to-4.6 and lower T_(DMC)ages of 1598–1469 Ma and apatite Sr-Nd isotopes,indicating a lithospheric mantle source.The ore-related rocks have higher oxygen fugacity of mean∆FMQ+2.00 and X_(F)/X_(OH)of 8.36–175 than the ore-barren rocks of mean∆FMQ+1.43 and3.72–4.96.It was inferred that magma source,water content,and oxygen fugacity emerge as critical factors governing the regional Cu-Au mineralization potential.
基金financially supported by CAMM(Center of Advanced Mining and Metallurgy/Green Flotation),as a center of excellence at the Luleå University of Technology.
文摘The global reliance on phosphate rock for agriculture and other industries,coupled with chemical regulations in developed countries,has driven the search for green alternatives in apatite flotation.This review investigates eco-friendly collectors’effectiveness in promoting sustainable mineral processing,guiding future alternatives to traditional reagents.The manuscript discussed the surface properties of apatite and its interaction with eco-friendly collectors,assessing existing fundamental studies.This study sought to:(1)define,organize,and classify“eco-friendly”collectors;(2)evaluate their effect in IEP and contact angle;(3)provide a better understanding of the adsorption behavior of the different fatty acid chains into apatite surface;(4)assess their ability to reversely and directly float apatite;(5)address gaps to achieve selectivity and process optimization.Outcomes demonstrated that fatty acids are largely applied,but other renewable sources of these reagents have been promisingly evaluated.In addition,other natural reagents have been tested,and new green synthetics have demonstrated synergistic effects when combined with fatty acids,yielding significant improvements in grade and recovery.However,collector effectiveness varies with ore characteristics,like particle size and surface properties,which remain underexplored.Future research should design tailored collectors that align with mineralogical differences to enhance selectivity.
基金This study was jointly supported by the Science&Technology Fundamental Resources Investigation Program(2022FY101800)National Science Foundation(92162212)+1 种基金the project from the Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences,Wuhan)(TPR-2022-22)the International Geoscience Programme(IGCP-675)。
文摘The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.
基金funded by the Major Research Plan of the National Natural Science Foundation of China(92162323)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0430101)Guizhou Provincial Science and Technology Projects No.ZK[2023]052.
文摘Lithium is a critical strategic metal with signifi-cant reserves in pegmatites,serving as the primary source for global Li production.Apatite has attracted increasing attention as an indicator in petrogenesis studies and for the exploration of ore deposits.In this study,we investigated the volatile compositions and major and trace elements of apatite from the Qiongjiagang pegmatite-type lithium deposit in Himalaya.Apatite derived from spodumene pegmatite exhibits relatively constant and high total rare earth element(ΣREE+Y)concentrations,ranging from 5899 to 8540 ppm.In contrast,apatite in barren pegmatite displays evidently lower(ΣREE+Y)concentrations,varying between 1345 and 3095 ppm.The REE patterns of apatite in spodumene pegmatite generally exhibit a flat shape[(La/Yb)N=1.55-2.15)],with distinctively negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.14-0.22),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.03-1.13),and low Y/Ho ratios(28-30).By contrast,apatite in barren pegmatite shows middle rare earth element(MREE)-depleted downward-convex patterns[(La/Yb)N=1.99-20.4)],strongly negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.01-0.14),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.10-1.24),and high Y/Ho ratios(30-55,with an average of 50).Overall,the high concentrations ofΣREE(and Y)and low Th/U and Y/Ho ratios can serve as diagnostic indicators to distinguish apatite in spodumene pegmatite from that in barren pegmatite.Furthermore,the flat REE pattern may represent a common feature of apatite from lithium deposits.Differences in the Ce and Eu anomalies between apatite from these two kinds of pegmatites likely reflect formation under different redox conditions.Consequently,based on calculations derived from apatite volatile compositions,the melt associated with spodumene pegmatite may contain higher water content compared to that of the barren one.Therefore,the mineralized pegmatite system may incorporate substantial amounts of H_(2)O-rich fluids,which play a crucial role in lithium mineralization.
基金supported by the National Natural Science Foundation of China(42372071,41102037)Shaanxi public welfare geological survey project(202409)the Foundation for the Author of National Excellent Doctoral Dissertation of China(201324).
文摘The Triassic granitoids and associated diorites in the Qinling orogenic belt reveal critical evidence of crust-mantle interaction during the terminal collision between the North China and Yangtze Blocks.This study presents new constraints from zircon U-Pb age,Lu-Hf isotopes,and amphibole-plagioclase-apatite geochemistry for the Maoerliang diorite in the Foping area.Zircon U-Pb dating yields a crystallization age of 212±2.8 Ma,withεHf(t)values ranging from−8.6 to+3.0 and corresponding twostage Hf model ages(T_(DM2))of 886-1479 Ma,indicative of derivation from an evolved lithospheric mantle source.Petrogenetic indicators reveal a mantle affinity:amphiboles exhibit high MgO(9.8-11.2 wt%)and elevated Nb/Ta ratios(14.3-18.1),while apatites display F-rich(2.1-2.8 wt%)and Cl-poor(0.08-0.15 wt%)characteristics.Thermobarometric calculations based on amphibole chemistry constrain crystallization conditions of 805-866℃and 211-383 MPa,corresponding to mid-crustal emplacement depths(8-14 km).Both amphibole and zircon indicate elevated oxygen fugacity(ΔNNO=−4.08 to−3.71;ΔFMQ=−1.14 to+3.96)and hydrous magma conditions(H_(2)O=4.22-4.94 wt%).Late-stage plagioclase crystallization(An21-26.5)reflects prolonged fractional crystallization in a hydrous dioritic magma.These diagnostic features-mantle-derived signatures,high f O_(2),and hydrous nature-exhibit remarkable convergence with gold-mineralized granites in the East Qinling.Our findings suggest that Triassic dioritic magmatism may have played an underappreciated role in facilitating gold enrichment processes within the South Qinling metallogenic belt.
基金financially supported by the National Natural Science Foundation of China(Grant No.41902224,41602209).
文摘Detrital zircon and apatite U-Pb-Hf isotope and trace element analyses of the late Mesoproterozoic to early Neoproterozoic strata in southern Jilin provide detailed information on the sediment provenance and tectonic setting of the northeastern margin of the North China Craton(NCC).Here,we present U-Pb and Lu-Hf analyses of 712 detrital zircons,and U-Pb analyses of 347 detrital apatites from the Baifangzi,Diaoyutai and Qiaotou formations.The Baifangzi and Diaoyutai formations are dominated by Neoarchean(2.5-2.6 Ga)and Paleoproterozoic(1.8-1.9 Ga)zircons,indicating a predominant NCC provenance.The Qiaotou Formation is dominated by Mesoproterozoic(1.5-1.7 Ga and 1.1-1.3 Ga)zircons with mainly positiveεHf(t)values,which are similar to those from eastern Laurentia,implying a significant provenance transition.The detrital apatite age spectra of the Baifangzi and Diaoyutai Formations show major populations at 1.8-1.9 Ga and 1.1-1.3 Ga.Based on their trace element compositions,the Mesoproterozoic apatites were mainly sourced from metamorphic rocks,indicating regional metamorphism occurred in the NCC during 1.1-1.3 Ga.Combining these data with regional studies,we propose that the NCC was adjacent to eastern Laurentia during the assembly of the Rodinia supercontinent.
基金supported by the Qinghai Provincial Special Fund for Geological Exploration-Deep Mineral Exploration Breakthrough Demonstration Project in Key Ore Concentration Areas of Qinghai Province(No.2023085029ky004)New Round of National Strategic Action for Mineral Exploration Breakthrough-Research and Demonstration of Air-Ground Collaborative Efficient Technologies for Copper-Nickel Sulfide Deposits in the East Kunlun Plateau Desert Region(No.ZKKJ202416)+1 种基金National Key R&D Program of China-Novel Geochemical Exploration Technologies for Desert Gobi and Alpine Grassland Shallow Overburden Terrains(No.2024ZD1002403)Kunlun Talent Program of Qinghai Province jointly support。
文摘A set of ultramafic-mafic-felsic rock assemblages was discovered in the Long-shenggeng area of the eastern part of the East Kunlun orogenic belt.Petrography,chronology and whole-rock geochemistry were conducted on this set of intrusive rock assemblages.U-Pb dating of apatite shows that the lherzolite formed at 492±5 Ma,the granite at 473±6 Ma,and the diabase at 260±14 Ma,respectively.The lherzolites belong to a supra-subduction zone type(SSZ-type)ophiolite component above a subduction zone;the granites formed in an ocean-continent subduction setting;and the diabases represent products of partial melting of an asthenospheric mantle at shallow depth.The East Kunlun orogenic belt features the East Kunzhong and Buqingshan-Animaqing ophiolitic mélange belts,with the latter representing remnants of the Proto-Tethys Ocean.The Late Cambrian lherzolites and granites in the Longshenggeng area were magmatic products of the back-arc ocean basin and island arc formed during the northward subduction of the Proto-Tethys Ocean.Subsequently,extensive island arc magmatism occurred from the Late Permian to Middle Triassic,driven by the northward subduction of the Paleo-Tethys Ocean beneath the East Kunlun Block.The diabase may have formed during the transition from subduction to post-collisional extension.
文摘Passive-roof duplexes accommodate shortening at the mountain front of many fold-and-thrust belts worldwide.These structures typically manifest at the surface by hinterland-verging backthrusts that decouple thin-skinned thrust sheets from underlying foreland-verging duplexes.Although the main fac-tors controlling the development of passive-roof duplexes have mostly been identified,some of their intrinsic characteristics are still poorly defined.These relate to their spatio-temporal relationships to thrust faults located further inland in orogens,and their ability to transport younger rocks over older ones.This study explores these issues in the Casentino-Romagna axial sector of the Northern Apennines,which expose regional forethrusts and backthrusts.Detailed field mapping and analysis of superposed tectonic structures were integrated with apatite fission-track dating for constraining the tim-ing of rock exhumation and correlated tectonic events.Collectively,the results have allowed us to inter-pret the evolution of the study area in terms of two main deformation stages.Specifically,a first,long phase(D_(1))progressed from NE-directed,in-sequence thrusting(∼18 to∼10-9 Ma)to late out-of-sequence thrusting(∼8-5 Ma).A successive deformation phase,that we refer to as D_(2)(∼4-2 Ma),con-sisted of backthrusts and associated folds that were ubiquitous and systematically overprinted onto the foreland-verging D_(1)structures.Such retrovergent structures identify a late deformation phase dom-inated by the development of passive-roof duplexes that propagated hinterlandward into the orogen up to beyond the primary watershed ridge.Orogen-scale processes controlled the evolution of forelandward D_(1)-phase thrusts,although late erosion could have played a major role by bringing the Apennine thrust wedge toward an undercritical state.The latter conditions could have contributed to keeping the out-of-sequence thrusts active,and eventually promoted the development of the D_(2)passive-roof duplexes.
基金supported by the National Natural Science Foundation of China(Grant Nos.41530963,42406077)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2022QD087)the National Natural Science Foundation of China(Grant Nos.42376060,41176038)。
文摘The temporal and spatial evolution of the Ailao Shan-Red River(ASRR)fault zone,which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau,is crucial for analyzing the uplift and growth of the plateau.Based on the petrology and apatite fission track analysis,the tectonic history and active pattern of the ASRR fault zone since the middle Miocene are determined in this study.The ASRR fault zone exhibits 12-8Ma and 8-4 Ma rapid cooling phases since the middle Miocene.The 12-8 Ma and 8-4 Ma cooling may imply that the dextral movement of the ASRR fault zone presents a migration trend from northwest to southeast,accompanied by the weakening of the activity intensity,which is directly related to deformation processes,including extrusion boundary migration and active tectonic movements of the southeastern Tibetan Plateau,since the middle-late Miocene.
基金supported by the projects of the China Geological Survey(DD20230543,DD20221770).
文摘Fluorine(F)-enriched soils,resulting from geogenic processes or superimposed by anthropogenic activities,have raised significant concerns due to their phytotoxicity and potential threats to human health.Soils in central Guizhou Province exhibit F enrichment,with a mean F concentration of 1067 mg/kg.However,the associated human health risks and geochemical mechanisms driving F enrichment in these soils remain insufficiently understood.In areas with a natural geological background,the average concentrations of F in rice,vegetables,drinking water,and ambient air are 1.54 mg/kg,0.54 mg/kg,0.16 mg/L,and 0.29μg/m^(3),respectively.In contrast,samples collected near phosphorous chemical plants demonstrate elevated F concentrations:1.78 mg/kg in rice,1.53 mg/kg in vegetables,0.20 mg/L in drinking water,and 11.98μg/m^(3) in ambient air.Fluorine in soils was immobilized by apatite and clay minerals,and hardly transferred into water and crops.The fixation of F-by Ca^(2+)in water and by Fe/Al hydroxides and clay minerals in bottom sediment further reduces F concentrations in water.As a result,hazard quotient(HQ)values below 1.0 indicate negligible fluorine-related health risk in geological background regions.However,ambient air near phosphorous chemical plant exhibited a 41.3-fold increase in F concentration compared to geological background regions.Fluorine-laden emissions can be directly inhaled or deposited on vegetable leaves and orally ingested into human bodies.Improvement of F-rich waste gas disposal and restricted leafy vegetable cultivation are effective measures to reduce F health risks in phosphorous chemical plant regions.
基金Projects(51172050,51102060,51302050)supported by the National Natural Science Foundation of ChinaProject(HIT.ICRST.2010009)supported by the Fundamental Research Funds for Central Universities,ChinaProject(HIT.NSRIF.2014129)supported by the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology,China
文摘Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and phase constitues, roughness, contact angle and apatite induction of the alkali-treated coatings were studied and compared. Scanning electron microscope(SEM) was applied to observe the morphologies, X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to detect the phase constitutes and chemical compositions, a surface topography profilometer was used to analyze the surface roughness, and contact angle was measured by liquid drop method. Alkali treatements result in the formation of Na2Ti6O13 and Na2Ti3O7 phase on the MAO coating, which leads to the increase of surface roughness and the decrease of contact angle. Experimental results showed that the apatite induction of the alkali-treated coatings was dependent on the applied alkali concentrations during treatments, and Na+concentration can promote the formation of apatite phase.
基金Project supported by the High Level Returned Overseas Chinese Scholars (No. 2005-118)the Returned Overseas Chinese Scholars (No. 2004-99)the Innovation Fund of Chinese Research Academy of Environmental Sciences (No. 2004-021).
文摘Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.
基金supported by the Shandong Geological Survey (Nos. 203027160439, 213027160438)Geological Investigation Work Project of China Geological Survey (Grant No. 12120115069701)+1 种基金Scientific Innovation Practice Project of Postgraduates of Chang’an University (2018019)Fundamental Research Funds for the Central Universities (No. 300102278402)
文摘The Weishan REE deposit is located at the eastern part of North China Craton(NCC), western Shandong Province. The REE-bearing carbonatite occur as veins associated with aegirine syenite. LA-ICP-MS bastnaesite Th-Pb ages(129 Ma) of the Weishan carbonatite show that the carbonatite formed contemporary with the aegirine syenite. Based on the petrographic and geochemical characteristics of calcite, the REEbearing carbonatite mainly consists of Generation-1 igneous calcite(G-1 calcite) with a small amount of Generation-2 hydrothermal calcite(G-2 calcite). Furthermore, the Weishan apatite is characterized by high Sr, LREE and low Y contents, and the carbonatite is rich in Sr, Ba and LREE contents. The δ^(13)Cv-PDB(-6.5‰ to -7.9‰) and δ^(13)OV-SMOW(8.48‰-9.67‰) values are similar to those of primary, mantlederived carbonatites. The above research supports that the carbonatite of the Weishan REE deposit is igneous carbonatite. Besides, the high Sr/Y, Th/U, Sr and Ba of the apatite indicate that the magma source of the Weishan REE deposit was enriched lithospheric mantle, which have suffered the fluid metasomatism. Taken together with the Mesozoic tectono-magmatic activities, the NW and NWW subduction of Izanagi plate along with lithosphere delamination and thinning of the North China plate support the formation of the Weishan REE deposit. Accordingly, the mineralization model of the Weishan REE deposit was concluded: The spatial-temporal relationships coupled with rare and trace element characteristics for both carbonatite and syenite suggest that the carbonatite melt was separated from the CO_2-rich silicate melt by liquid immiscibility. The G-1 calcites were crystallized from the carbonatite melt, which made the residual melt rich in rare earth elements. Due to the common origin of G-1 and G-2 calcites, the REE-rich magmatic hydrothermal was subsequently separated from the melt. After that, large numbers of rare earth minerals were produced from the magmatic hydrothermal stage.
基金supported by theNational Key Basic Research Program(MOST grants2007411305 to Z J Guo)
文摘The Qilian Shan lies along the northeastern edge of the Tibetan Plateau. To constrain its deformation history, we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediately north of the mountain range. Paleocurrent measurements, sandstone compositional data, and facies analysis of Cenozoic stratigraphic sections suggest that the Jiuxi Basin received sediments from the Altyn Tagh Range in the northwest, initially in the Oligocene （-33 Ma）, depositing the Huoshaogou Formation in the northern part of the basin. Later, the source area of the Jiuxi Basin changed to the Qilian Shan in the south during Late Oligocene （-27 Ma）, which led to the deposition of the Baiyanghe Formation. We suggest that uplift of the northern Qilian Shan induced by thrusting began no later than the Late Oligocene. Fission-track analysis of apatite from the Qilian Shan yields further information about the deformation history of the northern Qilain Shan and the Jiuxi Basin. It shows that a period of rapid cooling, interpreted as exhumation, initiated in the Oligocene. We suggest that this exhumation marked the initial uplift of the Qilian Shan resulting from the India-Asia collision.
基金funded by the National Natural Science Foundation of China(No.41572190)the National Program on Key Basic Research Project from the Ministry of Science and Technology of China(No.2015CB453002)the China Geological Survey(Nos.12120115070101,1212010611806,1212010611817)
文摘The apatite fission track（AFT） ages and thermal modeling of the Longshoushan and deformation along the northern Hexi Corridor on the northern side of the Qinghai-Tibetan Plateau show that the Longshoushan along the northern corridor had experienced important multi-stage exhumations during the Late Mesozoic and Cenozoic. The AFT ages of 7 samples range from 31.9 Ma to 111.8 Ma.Thermal modeling of the AFT ages of the samples shows that the Longshoushan experienced significant exhumation during the Late Cretaceous to the Early Cenozoic（-130-25 Ma）. The Late Cretaceous exhumation of the Longshoushan may have resulted from the continuous compression between the Lhasa and Qiangtang blocks and the flat slab subduction of the Neo-Tethys oceanic plate, which affected wide regions across the Qinghai-Tibetan Plateau. During the Early Cenozoic, the Longshoushan still experienced exhumation, but this process was caused by the Indian-Eurasian collision. Since this time,the Longshoushan was in a stable stage for approximately 20 Ma and experienced erosion. Since -5 Ma,obvious tectonic deformation occurred along the entire northern Hexi Corridor, which has also been reported from the peripheral regions of the Qinghai-Tibetan Plateau, especially in the Qilianshan and northeastern margin of the plateau. The AFT ages and the Late Cenozoic deformation of the northern Hexi Corridor all indicate that the present northern boundary of the Qinghai-Tibetan Plateau is situated along the northern Hexi Corridor.
