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| 1 | Petrogenesis of highly fractionated I-type granites in the Zayu area of eastern Gangdese, Tibet: Constraints from zircon U-Pb geochronology, geochemistry and Sr-Nd-Hf isotopes显示文摘The Cretaceous granitoids in the middle and northern Gangdese, Tibet are generally interpreted as the products of anatexis of thickened deep crust genetically associated with the Lhasa-Qiangtang collision. This paper reports bulk-rock major element, trace element and Sr-Nd isotopic data, zircon U-Pb age data, and zircon Hf isotopic data on the Zayu pluton in eastern Gangdese, Tibet. These data shed new light on the petrogenesis of the pluton. Our SHRIMP zircon U-Pb age dates, along with LA-ICPMS zircon U-Pb age dates recently reported in the literature, indicate that the Zayu pluton was emplaced at about 130 Ma, coeval with Early Cretaceous magmatic rocks in other areas of eastern Gangdese (e.g., Rawu, Baxoi areas) and the Middle Gangdese. The Zayu pluton samples lack amphibole and muscovite, and are compositionally characterized by high SiO2 (69.9%―76.8%), K2O (4.4%―5.7%), and low P2O5 (0.05%―0.12%). These samples also have A/CNK values of 1.00-1.05, and are enriched in Rb, Th, U, and Pb, and depleted in Ba, Nb, Ta, Sr, P, Ti, and Eu. These geochemical features suggest that the Zayu pluton samples are metaluminous to slightly peraluminous and are of highly fractionated I-type granite. The Zayu pluton samples have high εNd(t) values (-10.9--7.6) and low initial 87Sr/86Sr ratios (0.7120- 0.7179) relative to melts derived from mature continental crust in the Gangdese (e.g., Ningzhong Early Jurassic strongly peraluminous granite). The Zayu pluton samples are heterogeneous in zircon εHf(t) values (-12.8--2.9), yielding ancient zircon Hf crustal model ages of 1.4―2.0 Ga. The data obtained in this study together with the data in the recent literature suggest that the Early Cretaceous granitoids in eastern Gangdese represent the eastward extension of the Early Cretaceous magmatism in the middle Gangdese, and that the Lhasa micro-continent block with ancient basement may extend for ~2000 km from east to west. Zircon Hf isotopic data and bulk-rock zircon saturation temperature (789-821℃) indicate that mantle-derived materials likely played a role in the generation of the Zayu pluton. We propose that the Zayu pluton was most likely generated in a setting associated with southward sub- duction of the Bangong-Nujiang ocean floor, where mantle wedge-derived magmas may have providedthe heat and material for the anatexis of ancient crust of the Lhasa micro-continent, resulted in hybrid melts (i.e., mantle-derived basaltic magmas + crust-derived felsic magmas). Such hybrid melts with subsequent fractional crystallization are responsible for the highly evolved Zayu pluton (crust thick- ening is not a prerequisite). | ZHU DiCheng MO XuanXue WANG LiQuan ZHAO ZhiDan NIU Yaoling ZHOU ChangYong YANG YueHeng | 2009 | Science China Earth Sciences2009，52，9： | 107 |
| 2 | Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning,China:New ^(40)Ar/^(39)Ar dating of the Yixian and Tuchengzi Formations显示文摘We report new 40Ar/39Ar dating results ob-tained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby ba-saltic sill. The second is the Yixian Bed 9 tuff from Heng-daozi considered by Lo et al. to be unaffected by metamor-phism and whose age, based on total fusion 40Ar/39Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion 40Ar/39Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca/K ratios, excellent reproducibility and gave a mean age of 125.0 ± 0.18 (1SD) ± 0.04 (SE) Ma. Single sanidine | C. C. Swisher III, WANG Xiaolin, ZHOU Zhonghe, WANG Yuanqing, JIN Fan, ZHANG Jiangyong , XU Xing, ZHANG Fucheng & WANG YuanDepartment of Geological Sciences, Wright Labs, Rutgers University, Piscataway, New Jersey 08854, USA (e-mail: cswish@rutgers. rci.e | 2002 | Chinese Science Bulletin2002，47，2： | 83 |
| 3 | Peat record reflecting Holo-cene climatic change in the Zoige Plateau and AMS radiocarbon dating显示文摘Through the use of reliable AMS dating of high resolution (15-30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well. | ZHOU Weijian LU Xuefeng WU Zhengkun DENG Lin A.J.T.Jull D.Donahue W.Beck | 2002 | Chinese Science Bulletin2002，47，1： | 68 |
| 4 | Chronology and geochemistry of metavolcanic rocks from Heigouxia Valley in the Mian-Lue tectonic zone, South Qinling——Evidence for a Paleozoic oceanic basin and its close time显示文摘The metavolcanic rocks of greenschist fades developed at Heigouxia Valley in the Mian-Lue tectonic zone, South Qinling orogenic belt is a bimodal volcanic series. It is composed of K-poor, Na-rich tholeiite and dacite-rhyolite. The trace elements characteristics with flat REE pattern of these tholeiites are similar to those of MORB. The Sm-Nd whole rock isochron age of(242±21) Ma and Rb-Sr whole rock isochron age of (221±13) Ma of this metavolcanic series consistently indicate their rnetamorphic time. Their relatively high initial εNd value of +6.1 at the rnetamorphic age (242 Ma) suggest that the volcanic rocks were derived from a depleted MORB type mantle source. Their trace elements and Nd isotope compositions suggest an oceanic basin developed from a rift on the continental margin of the Yangtze Block during the late Paleozoic and closed in the Triassic, This is the first case clearly showing the existence of relict of late Paleozoic oceanic crust in Fast Qinling belt, which provides important | 李曙光 孙卫东 张国伟 陈家义 杨永成 | 1996 | Science China Earth Sciences1996，39，3： | 59 |
| 5 | The ages of U-Pb and Sm-Nd for eclogite from the western segment of Altyn Tagh tectonic belt——Evidence for existence of Caledonian orogenic root显示文摘The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd isotopic data yield a whole rock-garnet-omphacite isochron of (500 ?10) Ma. The U-Pb isotopic measurements of zircons show that the four | Jianxin Zhang Zeming Zhang Zhiqin Xu Jingsui Yang Junwen Cui | 1999 | Chinese Science Bulletin1999，44，24： | 46 |
| 6 | Rising process of the Qinghai-Xizang (Tibet) Plateau and its mechanism显示文摘The rising of the Qinghai-Xizang Plateau has character of multistage (45-38 Ma, 25-17 Ma, 13-8 Ma, 3 Ma-present), inhomogeneity and hetero-speed. The whole uprising of the plateau and local rapid rising in its periphery since Late Pliocene is a synthetical result of at least two or more mechanisms. | 钟大赉 丁林 | 1996 | Science China Earth Sciences1996，39，4： | 49 |
| 7 | Potash-rich volcanic rocks and lamprophyres in western Shandong Province:^(40)Ar-^(39)Ar dating and source tracing显示文摘Highly precise 40Ar-39Ar dating results demon-strate that the ages of potash-rich volcanic rocks in western Shandong Province are 114.7-124.3 Ma, and that of the lamprophyres is 119.6 Ma. The potash-rich volcanic rocks have relatively high (87Sr/86Sr)i ratios ( 0.708715-0.711418) and distinctly negative εNd values ( -11.47--17.54), and are enriched in radiogenic lead (206Pb/204Pb=17.341-17.622, 207Pb/204Pb=15.525-15.538, 208Pb/204Pb=37.563-37.684). Similarly, the lamprophyres also have quite low εNd values (-11.57 - -19.64). Based on the fact that the Sr, Nd and Pb isotopic compositions of potash-rich volcanic rocks are very consistent with that of the clinopyroxene separates, and by integrating comprehensive analyses of their tectonic settings, and extensive comparisons of the Sr, Nd isotopic composi-tions with that of the related simultaneous rocks, it is con-cluded that the potash-rich volcanic rocks and lamprophyres in western Shandong Province were most possibly derived from the partial melting | QIU Jiansheng, XU Xisheng & LO Ching-HuaState Key Laboratory of Mineral Deposit Research of Nanjing University, Nanjing 210093, China Department of Earth Sciences, Nanjing University, Nanjing 210093, China Department of Geology, Taiwan Unive | 2002 | Chinese Science Bulletin2002，47，2： | 39 |
| 8 | ^(40)Ar-^(39)Ar dating and geological implication of auriferous altered rocks from the middle-deep section of Q875 gold-quartz vein in Xiaoqinling area, Henan,China显示文摘The 40Ar-39Ar age method is employed in this work to analyze the auriferous altered rocks from the middle-deep section of the Q875 gold-quartz vein in the Xiao-qinling area, and the results show that the main gold deposition of the Q875 occurred in ca. 128-126 Ma. As a typical gold-bearing quartz vein in this gold-rich area, the age data obtained from the Q875 also constrain on the metallogenic time of the lode gold deposits developed in the same geological settings. This geochronological study supplies new evidence for further understanding the timing of gold mineralization, the genesis of gold deposits and the geodynamic settings in Xiaoqinling area. | WANG Yitian, MAO Jingwen, LU Xinxiang & YE AnwangInstitute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China Institute of Geological Sciences, Henan Province, Zhengzhou 450053, China Lingbao Bureau of Geology and Mineral | 2002 | Chinese Science Bulletin2002，47，20： | 36 |
| 9 | SHRIMP zircon U-Pb ages for the Paleoproterozoic metamorphic-magmatic events in the southeast margin of the North China Craton显示文摘A garnet-pyroxene bearing amphibolite as a xenolith hosted by the Mesozoic igneous rocks from Xuzhou-Suzhou area was dated by zircon SHRIMP U-Pb method, which yields a metamorphic age of 1918 ± 56 Ma. In addition, the zircons from a garnet amphibolite as a lens interbedded with marble in the Archean metamorphic complex named Wuhe group in the Bengbu uplift give a metamorphic U-Pb age of 1857 ± 19 Ma, and the zircons from Shimenshan deformed granite in the eastern margin of the Bengbu uplift give a magma crystallization U-Pb age of 2054 ± 22 Ma. Both the Xuzhou-Suzhou area and Bengbu uplift are located in the southeastern margin of the North China Craton. Therefore,these ages indicate that there is a Paleoproterozoic tectonic zone in the southeastern margin of the North China Craton, and its metamorphic and magmatic ages are consistent with those of the other three Paleoproterozoic tectonic zones in the North China Craton. In view of the large scale sinistral strike-slip movement occurred at the Mesozoic along the Tan-Lu fault zone, the position of the eastern Shandong area, which is a south section of the Paleoproterozoic Jiao-Liao-Ji Belt, was correlated to Xuzhou-Suzhou-Bengbu area prior to movement of the Tan-Lu fault zone. This suggests that the Xuzhou-Suzhou-Bengbu Paleoproterozoic tectonic zone might be a southwest extension of the Paleoproterozoic Jiao-Liao-Ji Belt. | GUO SuShu LI ShuGuang | 2009 | Science China Earth Sciences2009，52，8： | 33 |
| 10 | Structure and deformation around the Gyirong basin, north Himalaya, and onset of the south Tibetan detachment system显示文摘Gyirong basin and its adjacent area are located at a special position in the Himalayan orogen, where the south Tibetan detachment system (STDS) and N-S trending rift converged. The north Himalayan orogen here can be divided into five petrologic-tectonic units successively from south to north: 1) the Greater Himalayan crystalline complex (GHC); 2) the STDS shear zone; 3) the Tethyan Himalayan sedimentary sequence (THS); 4) the late Cenozoic sedimentary basins, such as Gyirong and Oma basins; and 5) the Malashan gneiss dome. Structural studies show that this area experienced four stages of deformation: 1) the earlier south-directed thrusting, preserved both in the GHC and THS; 2) top-down-to-north slip along the STDS, normal faults related to this slip formed the early controlling structures of the Cenozoic basins,and the tilted pattern of the blocks between the basins indicated a north-directed slip; 3) east-west extension, the resultant N-S trending normal fault formed the eastern boundary of the basins; and 4) late gravitational collapse. Zircon SHRIMP U-Pb dating on the syn-deformational (leuco-) granite along the STDS indicates that the major activity of the STDS occurred at ca. 26 Ma, but its onset may have begun as early as ca. 36 Ma. | YANG XiongYing ZHANG JinJiang QI GuoWei WANG DeChao GUO Lei LI PengYuan LIU Jiang | 2009 | Science China Earth Sciences2009，52，8： | 33 |
| 11 | SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau显示文摘Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.282615 to 0.282657, with εHf(t) values of 5.02±0.28, indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the 'Central Uplift' of the Qiangtang, northern Tibetan Plateau. | ZHAI QingGuo1 WANG Jun1, LI Cai2 & SU Li3 1 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China 2 College of Earth Sciences, Jilin University, Changchun 130061, China 3 The Geological Laboratory Center and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geo- sciences, Beijing 100083, China | 2010 | Science China Earth Sciences2010，53，5： | 31 |
| 12 | LA-ICP-MS zircon U-Pb dating from granitoids in southern basement of Songliao basin:Constraints on ages of the basin basement显示文摘Seven LA-ICP-MS zircon U-Pb datings from granitoids in the southern basement of the Songliao basin were done in order to constrain the ages of the basin basement. The cathodoluminescence (CL) images of the zircons from seven granitoids indicate that they are euhedral-subhedral ones with striped ab-sorption and obvious oscillatory zoning rims. The dating results show that a weighted mean 206Pb/238U age is 236±3 Ma for quartz diorite (sample No.T6-1) located in the western slope of the basin,that weighted mean 206Pb/238U ages are 319±1 Ma (2126 m) and 361±2 Ma (1994 m) for diorite (sample No.YC1-1) and granite (sample No.YC1-2) located in northern part of southeastern uplift of the basin,respectively,and that weighted mean 206Pb/238U ages are 161±5 Ma,165±2 Ma,165±1 Ma and 161±4 Ma for samples Q2-1,SN121,SN122,and SN72 granitoids located in southern part of southeastern uplift of the basin,respectively. The statistical results of ages suggest that the middle Jurassic granitoids con-stitute the main part of basement granitoids,and that the Hercynian and Indo-Sino magmatisms also occur in the basin basement. It is implied that the Songliao basin should be a rift one formed in the intracontinent or active continental margin settings in the late Mesozoic after the Middle Jurassic orogeny took place. | GAO FuHong XU WenLiang YANG DeBin PEI FuPing LIU XiaoMing HU ZhaoChu | 2007 | Science China Earth Sciences2007，50，7： | 31 |
| 13 | TIMING OF COLLISION BETWEEN THE NORTH AND SOUTH CHINA BLOCKS——THE Sm-Nd ISOTOPIC AGE EVIDENCE显示文摘Sm-Nd isotopic ages for C-type eclogite (243.9±5.6 Ma) and mafic and ultramafic rocks(230.6±30.7 Ma and 402.6±17.4 Ma) from the Qinling-Dabieshan orogenic belt are reported.These ages suggest that at the early Triassic, the North and South China Blocks have beenunited along the Qinling-Dabieshan collision zone, and before the final collision, a se-ries of ophiolite obductions took place successively away from the continental marginduring the Paleozoic. | 李曙光 S.R.HART 郑双根 刘德良 张国伟 郭安林 | 1989 | Science China Chemistry1989，32，11： | 33 |
| 14 | 德兴矿集区花岗闪长斑岩锆石U-Pb年龄、Hf同位素特征及其意义显示文摘德兴矿集区位于赣东北地区,是中国东部中生代钦杭成矿带中的大型铜金铅锌矿集区之一,集中了铜厂、富家坞和朱砂红斑岩铜钼(金)矿、银山银铜铅锌多金属矿和金山金矿等大型、超大型矿床。本文在系统的野外地质调查与样品采集的基础上,对铜厂、富家坞、朱砂红及银山花岗闪长斑岩进行了LA-MC-ICP-MS锆石U-Pb定年和原位Hf同位素分析。德兴矿集区花岗闪长斑岩的LA-MC-ICP-MS锆石U-Pb的4组年龄分别为:(171±1.2)Ma(铜厂)、(172±0.68)Ma(富家坞)、(173±1.3)Ma(朱砂红)、(176±1.5)Ma(银山),表明这些岩体均为中侏罗世的产物。样品Hf两阶段模式年龄平均值分别为861 Ma、876 Ma、904 Ma和941 Ma,正的εHf(t)平均值在4.34-5.54,Zr/Hf比值接近于上地幔的Zr/Hf比值。锆石Hf同位素组成显示,岩浆源区主要来源于亏损地幔组分,但在岩浆演化中遭受了古老地壳物质的混染,幔源物质在德兴矿集区花岗闪长斑岩的形成过程中发挥了重要作用。德兴矿集区4个矿床成岩成矿的最重要时期在170-175 Ma,该矿集区岩浆热液系统持续活动可能是该大型矿集区形成的重要原因。 | 水新芳 赵元艺 郭硕 吴德新 朱小云 王增科 | 2012 | 中国地质2012，39，6： | 33 |
| 15 | 黑龙江桦南地区黑龙江杂岩锆石U-Pb定年显示文摘黑龙江杂岩主要由绿片岩相变质岩和糜棱岩化构造片岩组成,长期以来与麻山杂岩一起被认为代表佳木斯地块的前寒武纪基底,但这种认识缺乏可信的同位素年代学及古生物资料的支持。对出露于黑龙江省东部桦南地区湖南营组绿片岩进行了锆石LA-ICP-MS U-Pb定年研究。结果显示锆石的Th/U比值为0.27~1.27,变化较大;获得两组^(206)Ph/^(238)U年龄数据:其加权平均年龄分别为:511±10Ma(n=13,MSWD=1.6)和274.7±3.6Ma(n=9,MSWD=0.91)。黑龙江杂岩中最老的年龄969~747Ma表现来自中元古和新元古代。这些年龄与黑龙江杂岩的年龄与来自俯冲碰撞变质事件的~511Ma的年龄结合起来,表明黑龙江杂岩中含有经历晚新元古——早古生代造山作用的碎屑锆石,亦或代表着在俯冲拼贴过程中混入的麻山杂岩块体。~275Ma年龄反映黑龙江杂岩经历的一次碰撞造山事件,可能与晚古生代古亚洲洋闭合相关。 | 李旭平 焦丽香 郑庆道 董晓 孔凡梅 宋召军 | 2009 | 岩石学报2009，25，8： | 30 |
| 16 | Re-Os isotope dating of molybdenites in the Huang-shaping Pb-Zn-W-Mo polymetallic deposit, Hunan Province, South China and its geological significance显示文摘The large-scale Huangshaping Pb-Zn-W-Mo polymetallic deposit is located in the central Nanling min- eralization zone, South China. Six molybdenite samples from the Huangshaping deposit were selected for Re-Os isotope measurement in order to define the mineralization age of the deposit. It yields a Re-Os isochron age of 154.8±1.9 Ma (2σ ), which is in accordance with the Re-Os model ages of 150.9― 156.9 Ma. This age is about 7 Ma younger than their host granite porphyry, which was dated as 161.6±1.1 Ma by zircon U-Pb method using LA-ICPMS. All these ages demonstrate that the Huang- shaping granite and related Pb-Zn-W-Mo deposit occurred in the middle Yanshanian period, when many other granitoid and related ore deposits emplaced and formed, e.g. the Qitianling granite and Furong tin deposit, the Qianlishan granite and giant Shizhuyuan W-Sn-Mo-Bi deposit and Jinchuantang Sn-Bi deposit in the nearby area. They constitute the main part of the magmatic-metallogenic belt of southern Hunan, and represent the large-scale metallogeny in middle Yanshanian in the area. The lower rhenium content in molybdenite of Huangshaping deposit suggests that the ore-forming material was mainly of crust origin. | YAO JunMing HUA RenMin QU WenJun QI HuaWen LIN JinFu DU AnDao | 2007 | Science China Earth Sciences2007，50，4： | 29 |
| 17 | Zircon U-Pb geochronological framework of Qitianling granite batholith, middle part of Nanling Range, South China显示文摘The Qitianling granite batholith (QGB) is located in the southern Hunan Province, middle part of the Nanling Range, South China. Its total exposure area is about 520 km2. Based on our 25 single grain zircon U-Pb age data and 7 published data as well as the geological, petrological, and space distribution characteristics, we conclude that QGB is an Early Yanshanian (Jurassic) multi-staged composite pluton. Its formation process can be subdivided into three major stages. The first stage, emplaced at 163―160 Ma with a peak at about 161 Ma, is mainly composed of hornblende-biotite monzonitic granites and locally biotite granites, and distributed in the eastern, northern, and western peripheral parts of the pluton. The second stage, emplaced at 157―153 Ma with a peak at 157―156 Ma, is mainly composed of biotite granites and locally containing hornblende, and distributed in the middle and southeastern parts of the pluton. The third stage, emplaced at 150―146 Ma with a peak at about 149 Ma, is mainly composed of fine-grained (locally porphyritic) biotite granites, and distributed in the middle-southern part of the pluton. Each stage can be further disintegrated into several granite bodies. The first two intrusive stages comprise the major phase of QGB, and the third intrusive stage comprises the additional phase. Many second stage fine-grained granite bosses and dykes intruded into the first stage host granites with clear chilling margin-baking phenomena at their intrusive contacts. They were emplaced in the open fracture space of the earlier stage consolidated rocks. Their isotopic ages are mostly 2―6 Ma younger than their hosts. Conceivably, the time interval from magma emplacement, through cooling, crystallization, solidification, up to fracturing of the earlier stage granites cannot exceed 2―6 Ma. During the Middle-Late Jurassic in the Qitianling area and neighboring Nanling Range, the coeval granitic and basic-intermediate magmatic activities were widely developed. It indicates that the Early Yanshanian period was the culmination time of magmatic activities in this region. The Nanling Range was under a post-orogenic, intracontinental geotectonic environment with an obvious lithospheric extension and thinning. The crust-mantle interaction played an important role in formation of granitic rocks in this region. | ZHU JinChu WANG RuCheng ZHANG PeiHua XIE CaiFu ZHANG WenLan ZHAO KuiDong XIE Lei YANG Ce CHE XuDong YU APeng WANG LuBin | 2009 | Science China Earth Sciences2009，52，9： | 27 |
| 18 | Zircon U-Pb SHRIMP ages of the Taiping (calc-alkaline)-Huangshan (alkaline) composite intrusion:Constraints on Mesozoic lithospheric thinning of the southeastern Yangtze Craton,China显示文摘The Taiping-Huangshan composite intrusion is a unique complex with characteristics changing from calc-alkaline (Taiping intrusion) to alkaline (Huangshan intrusion). Huangshan intrusion samples show a spectacular tetrad effect in their REE distribution patterns as well as non-CHARAC (charge-and radius-controlled) trace element behavior, indicating a highly evolved late-stage magma component. This composite intrusion provides a rare opportunity to investigate the variance of tectonic setting and lithospheric thinning of the southeastern Yangtze Craton in late Mesozoic era. Zircon SHRIMP U-Pb analyses yield an emplacement age of 140.6±1.2 Ma for the Taiping intrusion, and ages of 127.7±1.3, 125.7±1.4, 125.1±1.5, and 125.2±5.5 Ma for four samples from the Huangshan intrusion respectively. The ages for four different phases of the Huangshan intrusion agree within their small analytical errors, indicating that the emplacement was in a short time. The Taiping and Huangshan intrusions are intimately associated, but there is about 15 Ma interval between their intrusion, and the magma characters change from calc-alkaline to alkaline without transition. This probably corresponds to lithospheric thinning of the southeastern Yangtze Craton. This event possibly happened from about 141 Ma (the emplacement age of the Taiping intrusion), to 128 Ma (start of emplacement of the Huangshan intrusion). The thinning mechanism is dominantly delamination. | XUE HuaiMin WANG YingGeng MA Fang WANG Cheng WAN DeEn ZUO YanLong | 2009 | Science China Earth Sciences2009，52，11： | 28 |
| 19 | K-Ar dating of late Mesozoic volcanism and geochemistry of volcanic gravels in the North Huaiyang Belt, Dabie orogen: Constraints on the stratigraphic framework and exhumation of the northern Dabie orthogneiss complex显示文摘Two eruption episodes are identified through systematic field investigations and K-Ar dating of the late Mesozoic volcanic rocks in the North Huaiyang belt (NHB), Dabie orogenic belt, of which the earlier volcanic suite termed Maotanchang Fm. (Fm.) occurring at Jinzhai, Xianhualing and Maotanchang, etc., was erupted from 149 Ma to 138 Ma. The other named Xiaotian Fm. mainly distributed at Xiaotian, Shucheng, etc., was formed between 132 Ma and 116 Ma. During the eruption gap of the two volcanic suites deposited a volcano-sedimentary conglomerate layer, which are composed of the multi-compositional gravels, including the North Dabie orthogneiss complex (NDOC), volcanic gravels, etc. These volcanic gravels in the conglomerate layer show identical geochemical and isotopic compositions (87Sr/86Sr(t) =0.7084-0.7092,εNd(t) =-21.8--24.4) to the Maotanchang Fm. volcanic rocks (87Sr/86Sr = 0.7086-0.7102,εNd = -19.2-24.4), but significantly distinct from those of Xiaotian Fm. (87Sr/86Sr = 0.7076-0.7084, εNd= | Yuejun Wang Weiming Fan Feng Guo | 2002 | Chinese Science Bulletin2002，47，20： | 28 |
| 20 | Possible early Neoproterozoic magmatism associated with slab window in the Pingshui segment of the Jiangshan-Shaoxing suture zone: Evidence from zircon LA-ICP-MS U-Pb geochronology and geochemistry显示文摘We report here geochemical data, U-Pb zircon ages, and Hf isotopes for the high-Mg diorites (HMDs), Nb-enriched basaltic porphyrys (NEBPs) and plagiogranites (PLAGs) in the Pingshui segment of the Jiangshan-Shaoxing suture zone. The HMDs are characterized by high Mg# (>60), high Na and LREE contents, depletion of HREE and HFSE, and pronounced positive εNd(t) values of 7.0 to 7.7, similar to some adakitic high-Mg andesites. The NEBPs are relatively Na-rich (Na2O/K2O>6) and display high abundances of P2O5 (~1.00%), TiO2 (~3.08%) and HFSE (e.g., Nb=9.53-10.27 ppm). Their Nd isotopic compositions (εNd(t)=6.8-8.0) are comparable to those of the HMDs. The PLAGs are metaluminous (A/CNK=0.84-0.89) and sodic (Na2O/K2O>10). Their depletion in HFSE (e.g., Nb, Ta) is consistent with 'SSZ-type' plagiogranite. Zircon LA-ICP-MS U-Pb dating yields an age of 932±7 Ma for the HMD, 916±6 Ma for the NEBP, and 902±5 Ma for the PLAG, respectively, indicating that they were products of early Neoproterozoic magmatism. The PLAGs exhibit relatively high zircon Hf isotopes and positive εHf(t) values of 11.0 to 16.2, consistent with their Nd isotopic data (εNd(t)=7.5-8.4). Such features are similar to those of oceanic plagiogranites in ophiolites and distinct from those of crust-derived granites. The PLAGs were most likely derived from partial melting of subducted oceanic crust in an active continental margin. Considering these results in the context of the regional geology, we suggest that a slab window in the subducting oceanic crust between the Yangtze Block and Cathaysia Block was possibly the principal cause for the unique arc magmatism in the area. The upwelling asthenosphere below the slab window may have provided significant thermodynamic conditions. | CHEN ZhiHong GUO KunYi DONG YongGuan CHEN Rong LI LongMing LIANG YiHong LI ChunHai YU XiMing ZHAO Ling XING GuangFu | 2009 | Science China Earth Sciences2009，52，7： | 26 |
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