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Paleoenvironmental records from the northern South china Sea since the Last Glacial Maximum

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Acta Oceanologica Sinica 2010年第3期29卷 46-62页

作者： GE Qian CHU Fengyou XUE Zuo LIU J Paul DU Yuansheng FANG Yinxia faculty of earth sciences China University of Geosciences Wuhan 430074 China Key Laboratory of Submarine geosciences State Ocean Administration Hangzhou 310012 China Department of Marine Earth and Atmospheric Sciences North Carolina State University Raleigh NC 27695 USA

Core ZHS-176 contains the paleoenvironmental records from the northern South china Sea （NSCS） since the Last Glacial Maximum （LGM）. A coupled approach based on clay mineral assemblages, planktonic foraminiferal oxygen and carbon isotopes, and calcium carbonate content is used to trace the sources of the fine-grained sediment and to investigate the paleoenviornmental evolution in this area. Clay mineral assemblages are dominated by illite （average about 39%） and chlorite （about 27%）, which comes mainly from Taiwan and the East china Sea. Kaolinite, which accounts for about 13%, comes mainly from the Zhujiang （Pearl） River, and Luzon Island is the main source for smectite （about 21%）. The planktonic foraminiferal oxygen isotopic oscillations during the last glacial period are coeval with climate variations recorded in the Greenland ice core and Western Pacific sediment. These variations include the LGM, heinrich event 1, Bφlling-Allerφd （B/A）, and Younger Dryas. For the Holocene, three periods of strong precipitation （S1-S3） and three periods of weak precipitation （W1-W3） are identified. The oxygen isotopic record exhibits corre-lation with climate records from distant regions, including the high-latitude Northern hemisphere, providing evidence for global tele-connection among regional climate. A brief, negative planktonic foraminiferal carbon isotopic excursion during B/A reflects increased methane released from marine gas hydrate due to the rapid warming of the water. By comparing calcium carbonate content curves of the core ZHS-176 with these of other five boreholes lying above the lysocline, a remarkable low calcium carbonate event is found during the early Holocene in NSCS.

关键词： clay mineral oxygen and carbon isotopes calcium carbonate content South china Sea paleoenvironmental evolution

Relationship between environmental evolution and human activities in the northeastern Qinghai-Xizang Plateau throughout the past millennium and its implications for the onset of the Anthropocene

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Science china earth sciences 2024年第11期67卷 3536-3549页

作者： yang PU Xueqiong WEI Jianbao LIU Ke zhang Beibei LI Zhudeng WEI Mengmeng zhang Tong he Yanjun WANG Xiaohua SHAO School of Geographical sciences Nanjing University of Information Science and Technology Key Laboratory of Alpine Ecology Institute of Tibetan Plateau Research Chinese Academy of Sciences State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences

In current research on the Anthropocene, assessing the impact of human activities via stratigraphic records of sediments and demarcating the Anthropocene epoch globally are critical scientific issues that urgently need to be addressed. The northeastern Qinghai-Xizang Plateau(QXP), where humans first settled permanently in large numbers in the QXP, has varying sedimentary environments that are extremely sensitive to human activities. In contrast to other regions of the QXP, the northeastern sector boasts a richer array of climatic and environmental reconstruction sequences. This distinctive feature renders it an exemplary locale for investigating the stratigraphic boundary of the Anthropocene. Through in-depth analysis and integration of existing paleoclimate and paleoenvironment sequences in the northeastern QXP, we draw the following conclusions:(1) Throughout the past millennium, the impact of human activities on the environment of the northeastern QXP has become increasingly significant, especially in the past 200–300 years, gradually overshadowing climatic factors.(2) Since AD 1950,multiple physicochemical indicators related to human activities in the northeastern QXP have shown exponential growth,forming a distinct peak within the past millennium and clearly depicting the global “Great Acceleration” phenomenon and its development process.(3) Intensified human activities have driven swift environmental shifts and “decoupled” the interplay between climatic variations and the ecological environment, propelling the northeastern QXP into the “Early Anthropocene”from the “Late Holocene”. On the basis of the above findings, we construct a model suitable for identifying the stratigraphic boundary of the Anthropocene in the northeastern QXP and note that since the ecological environment in the northeastern QXP has entered the “Early Anthropocene”, the climate signals of certain physicochemical indicators in sediments are gradually becoming weaker, whereas the signals of

关键词： Anthropocene Qinghai-Xizang Plateau (QXP) Climate change Environmental evolution Human activities

Spin effect on redox acceleration and regioselectivity in Fe-catalyzed alkyne hydrosilylation

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National Science Review 2024年第2期11卷 155-167页

作者： Peng he Meng-yang Hu Jin-Hong Li Tian-zhang Qiao Yi-Lin Lu Shou-Fei Zhu Frontiers Science Center for New Organic Matter State Key Laboratory and Institute of Elemento-Organic Chemistry Nankai University

Iron catalysts are ideal transition metal catalysts because of the earths abundant, cheap, biocompatible features of iron salts. Iron catalysts often have unique open-shell structures that easily undergo spin crossover in chemical transformations, a feature rarely found in noble metal catalysts. Unfortunately, little is known currently about how the open-shell structure and spin crossover affect the reactivity and selectivity of iron catalysts, which makes the development of iron catalysts a low efficient trial-and-error program. In this paper, a combination of experiments and theoretical calculations revealed that the iron-catalyzed hydrosilylation of alkynes is typical spin-crossover catalysis. Deep insight into the electronic structures of a set of well-defined open-shell active formal Fe(0) catalysts revealed that the spin-delocalization between the iron center and the 1,10-phenanthroline ligand effectively regulates the iron center's spin and oxidation state to meet the opposite electrostatic requirements of oxidative addition and reductive elimination, respectively,and the spin crossover is essential for this electron transfer process. The triplet transition state was essential for achieving high regioselectivity through tuning the nonbonding interactions. These findings provide an important reference for understanding the effect of catalyst spin state on reaction. It is inspiring for the development of iron catalysts and other earth-abundant metal catalysts, especially from the point of view of ligand development.

关键词： spin effect spin-delocalization spin crossover iron-catalysis alkyne hydrosilylation

Effects of abnormally high heat stress on petroleum in reservoir——An example from the Tazhong 18 Well in the Tarim Basin

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Science china earth sciences 2008年第4期51卷 515-527页

作者： ZHU DongYa1, JIN ZhiJun1, HU WenXuan2 & zhang XueFeng3 1 Petroleum Exploration and Production Institute, china Petroleum & Chemical Corporation, Beijing 100083, china 2 Department of earth sciences, Nanjing university, Nanjing 210093, china 3 School of Resource and Information, china university of Petroleum, Beijing 102249, china Petroleum Exploration and Production Institute China Petroleum & Chemical Corporation Beijing China Department of earth sciences Nanjing University Nanjing China School of Resource and Information China University of Petroleum Beijing China

An igneous intrusion of 94m thick was discovered intruding into the Silurian sandstone from Tazhong 18 Well. The petroleum previously preserved in the Silurian sandstone reservoir was altered into black carbonaceous bitumen by abnormally high heat stress induced by the igneous intrusion. The reflec-tance of the carbonaceous bitumen reaches as high as 3.54%, indicating that the bitumen had evolved into a high thermal evolution level. Similar to the Silurian samples from the neighboring Tazhong 11, Tazhong 12, Tazhong 45 and Tazhong 47 wells, the distribution of C27, C28 and C29 steranes of the car-bonaceous bitumen is still "V" -shaped and can still be employed as an efficient parameter in oil source correlation. The "V" -shaped distribution indicates that the hydrocarbons from the Tazhong 18 and the neighboring wells were all generated from the Middle-Upper Ordovician hydrocarbon source rocks. However, the oil source correlation parameters associated with and terpanes had been changed greatly by the high heat stress and can no longer be used in oil source correlation. The δ 13C values of the pe-troleum from the neighboring wells are between -32.53‰ and -33.37‰, coincident with those of the Paleozoic marine petroleum in the Tarim Basin. However, the δ 13C values of the carbonaceous bitumen from the Tazhong 18 Well are between -27.18‰ and -29.26‰, isotopically much heavier than the pe-troleum from the neighboring wells. The content of light hydrocarbons (nC14-nC20) of the saturated hydrocarbon fraction in the carbonaceous bitumen is extremely higher than the content of heavy hy-drocarbons. The light/heavy hydrocarbon ratios (ΣnC21-/ΣnC22+) are between 4.56 and 39.17. In the saturated fraction, the even numbered hydrocarbons are predominant to the odd numbered, and the OEP (Odd to Even Predominance) values are between 0.22 and 0.49. However, the content of light hy-drocarbons in the petroleum from the neighboring wells is relatively low and the content of the even numb

关键词： Tarim Basin igneous intrusive abnormally high heat stress bitumen carbon isotope PAH

Eclogites in the interior of the Tibetan Plateau and their geodynamic implications

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Chinese Science Bulletin 2009年第15期54卷 2556-2567页

作者： zhang KaiJun1,2 & TANG XianChun2,3 1 Department of earth sciences, Nanjing university, Nanjing 210093, china 2 Guangzhou Institute of Geochemistry, Chinese Academy of sciences, Guangzhou 510640, china 3 Graduate university of Chinese Academy of sciences, Beijing 100049, china Department of earth sciences Nanjing University Nanjing China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate university of Chinese Academy of sciences Beijing China

Eclogites have been recently reported in the interior of the Tibetan Plateau, including in the central Qiangtang metamorphic belt, in the Basu metamorphic massif of the eastern Bangong-Nujiang suture zone, and at Songdo and Pengco in the eastern Lhasa terrane. Some typical ultrahigh-pressure (UHP) metamorphic phenomena, e.g., garnet exsolution from clinopyroxene, were documented in the Basu and Pengco eclogites. The UHP metamorphism in the interior of the Tibetan Plateau marked by these eclogites generally took place in the Early Mesozoic. Along with exhumation of these eclogites, (post-) collision-related magmatism extensively occurred around the central Qiangtang belt, the eastern Ban-gong-Nujiang suture zone, and the eastern Lhasa terrane. The occurrence of these Early Mesozoic ec-logites manifests an out-of-sequence evolution of the Tethys, and they could be a product of diachro-nous collision between the eastern Qiangtang terrane and the irregular continental margin of the united western Qiangtang-Lhasa plate, along the linked eastern Bangong-Nujiang-central Qiangtang zone. The collision-related magmatic rocks could have been originated from lithospheric thickening, melting, or detachment due to the collision. The presence of UHP metamorphic rocks in central Qiangtang and Basu implies likely continental deep-subduction, and the denudation of these two metamorphic zones could have served as the source of the Triassic turbidites in the Songpan-Garzê complex and the Ju-rassic turbidites in the western Bangong-Nujiang zone, respectively. However, studies of the eclogites in the interior of the Tibetan Plateau just began, and many principal aspects still remain to be explored, such as their distributions, typical lithologies and minerals, temperature-pressure conditions, timing of formation and exhumation, protoliths and tectonic setting, and relationship with the evolution of the Tethys and large-scale basins in Tibet.

关键词：地球动力学意义青藏高原榴辉岩

A Comparison about Metamorphism among the Oldest-Rock Units from Orogenic Belts of Dabie,Eastern Qinling and Eastern Kunlun of Central Mountain Ranges,china

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Journal of earth Science 1998年第3期17卷 10-15页

作者： Chen Nengsong zhang Kexin Wang Guocan Hou Guangjiu Zhu Yunhai faculty of earth sciences, china university of geosciences, wuhan 430074

The Dabie orogen, Eastern Qinling orogen and Eastern Kunlun orogen are the major components of the Central Mountain Ranges of china and each has distinctively metamorphic processes in their oldest rock units. The Dabie orogen oldest rock units had experienced an intermediate-higher pressure, upper amphibolite to lower granulite facies metamorphism in the Indosinian intracontinental subduction collision event. The clockwise pt path, synchronous attainment of t max and p max and a segment of high slope retrograde path suggest a tectono driven rapid exhumation of the oldest rock units to upper middle crustal level following the end of the subduction collision process. The oldest rock units, also called Qinling Group, of Eastern Qinling Mountains suffered intensively collisional metamorphism at an immature plate tectonic framework during Jinningian movement about 1 000 Ma ago. The clockwise pt path with reach of t max following several hundreds of MPa decreasing from p max suggests that the denudation of the deeply burial rock units was due essentially to isostatic relaxation. During the Caledonian stage, the highly metamorphosed oldest rock units suffered from a high t thermal event in arc environment and superimposed by contact metamorphism. After thermal peaks, the rock units were exhumed in a short distance and cooled down isobarically. No regional metamorphism higher than upper greenschist facies condition since 300 Ma has been traced within exposed rocks in the eastern portion of Northern Qinling orogen. The oldest rock units in the Eastern Kunlun orogen were metamorphosed to upper amphibolite facies to lower granulite facies rocks early or during the Luliang movement (some 1 800 Ma ago). The high grade metamorphic rock units had a long resident time at the deep crustal level, and were exhumed to middle upper crustal level during the Caledonian to hercynian tectonometamorphic events. Shallow erosion of

关键词： the oldest metamorphic rock units pt path geodynamics of metamorphism Dabie orogen Eastern Qinling orogen Eastern Kunlun orogen Central Mountain Ranges of china.

Geochemistry of high-Mg andesites from the early Cretaceous Yixian Formation, western Liaoning: Implications for lower crustal delamination and Sr/Y variations

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Science china earth sciences 2006年第9期49卷 904-914页

作者： WANG Xiaorui1, GAO Shan1,2, LIU Xiaoming1, YUAN Honglin1, HU Zhaochu1, zhang Hong1,3 & WANG Xuance4 1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest university, Xi`an 710069, china 2. State Key Laboratory of Geological Processes and Mineral Resources, china university of geosciences, wuhan 430074, china 3. Shenyang Institute of Geology and Mineral Resources, Shenyang 110032, china 4. Guangzhou Institute of Geochemistry, Chinese Academy of sciences, Guangzhou 510640, china State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi’an China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan China Shenyang Institute of Geology and Mineral Resources Shenyang China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

85 volcanic rocks of the Yixian Formation from the Sihetun type section werecollected and analyzed for geochemical and isotopic compositions. Major element compositionsindicate that the Sihetun volcanic rocks are high magnesium andesites with some basalts occurring atthe bottom of section. The Sihetun high magnesium andesites (SiO_2 = 52.82-59.31 wt%, Al_2O_3=14.15-16.35wt%) show many characteristics of adakites such as depletion in heavy rare-earth elements(HREE; Yb = 1.03-1.88 μg/g) and Y(12-20 μg/g) and high Sr (620-1323 μg/g) and Sr/Y(32-88), withhigh La_N/Yb_N ratio (10-25). They share similar major and trace element characteristics to volcanicrocks from the Xinglonggou Formation except their lower Nd isotope ratios (^(143)Nd/^(144)Nd(130Ma) = 0.5118-0.5119, ε_(Nd) (130Ma) = -11.6-13.8, ^(87)Sr/^(86)Sr (130 Ma) = *** were interpreted in a way that eclogite that formed at the base of thickened Archean lowercrust of the North china craton foundered into the convecting mantle and subsequently melted andinteracted with peridotite. However, compared to the Xinglonggou volcanic rocks, the source of theSihetun magma contained more ancient continental crustal material in order to explain its evolved Ndisotopes. The age of the Sihetun Formation was 120 to 130 Ma, and this indicates that delaminationlasted to the early Cretaceous period. The Sr contents and Sr/Y ratios of the Sihetun high-Mgandesites show significant negative correlations with SiO_2 for samples with SiO_2 > 56%. Thesesuggest that the Sr and Sr/Y values were reduced due to fractional crystallization of ***, the effect of crystallization on volcanic Sr and Sr/Y ratio has to be taken intoaccount.

关键词： High-Mg andesite, Adakite, Yixian Formation, North china Craton, delamination.

Discovery of Permian island-arc basalts in the Cenxi area and the tectonic significance──A piece of evidence for the paleo-Tethyan tectonic belt in western Guangdong and eastern Guangxi

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Chinese Science Bulletin 1998年第21期43卷 1838-1842页

作者： zhang Boyou 1, ZHAO Zhenhua 1, SHI Manquan 1, yang Shufeng 2 and CheN Hanlin 2 1. Guangzhou Institute of Geochemistry, Chinese Academy of sciences, Guangzhou 510640, china 2. Department of earth sciences, Zhejiang university, Hangzhou 310027, china Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Department of earth sciences Zhejiang University Hangzhou China

Cenxi Permian basalts are the late Palaeozoic island-arc type basalts first found in South china. REE and trace element characteristics and distribution patterns show that this volcanic formation, which has been isotopically dated at 261 MaB.P. by the 39Ar/ 40Ar method, is of an active continental marginal island arc type, and that the tectonic environment at that time was an island-arc marginal sea or minor ocean basin related with the paleo-Tethyan tectonic belt in western Guangdong-eastern Guangxi.

关键词： spilite-keratophyre pillow lava Permian continental margin paleo-Tethyan evolution.

Research on the dynamics of the South china Sea opening:Evidence from analogue modeling

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Science china earth sciences 2006年第10期49卷 1053-1069页

作者： SUN Zhen1,2, ZHOU Di1, ZHONG Zhihong3, XIA Bin2, QIU Xuelin1, ZENG Zuoxun4 & JIANG Jianqun5 1. CAS Key Laboratory of Marginal Sea Geology, South china Sea Institute of Oceanology, Chinese Academy of sciences, Guangzhou 510301, china 2. CAS Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of sciences, Guangzhou 510640, china 3. Department of Technology, Shenzhen Branch of CNOOC, Guangzhou 510240, china 4. faculty of earth sciences, china university of geosciences, wuhan 430074, china 5. Hainan Oil & Gas Exploration Company, Liaohe Oilfield Petrochina, Panjin 124010, china CAS Key Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China CAS Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Department of Technology Shenzhen Branch of CNOOC Guangzhou China faculty of earth sciences China University of Geosciences Wuhan China Hainan Oil & Gas Exploration Company Liaohe Oilfield PetroChina Panjin China

Independent of Indochina extrusion, the South china Sea experienced a process from passive continental rifting to marginal sea drifting. According to the fault patterns in the Beibu Gulf basin and the Pearl River Mouth basin, the continental rifting and early spreading stage from 32 to 26 Ma were controlled by extensional stress field, which shifted clockwise from southeastward to south southeastward. From 24 Ma on, the sea spread in NW-SE direction and ceased spreading at around 15.5 Ma. Integrated geological information with the assumption that the South china Sea developed along a pre-Cenozoic weakness zone, we did analogue experiments on the South china Sea evolu- tion. Experiments revealed that the pre-existing weakness zone goes roughly along the uplift zone between the present Zhu-1 and Zhu-2 depression. The pre-existing weakness zone is composed of three segments trending NNE, roughly EW and NEE, respectively. The early opening of the South china Sea is accompanied with roughly 15° clockwise rotation, while the SE sub-sea basin opened with SE extension. Tinjar fault was the western boundary of the Nansha block (Dangerous Ground), while Lupar fault was the eastern boundary of the Indochina, NW-trending rift belt known as Zengmu basin developed between above two faults due to block divergent of Indochina from Nansha. In the experiment, transtensional flower structures along NW-trending faults are seen, and slight inversion occurs along some NE-dipping faults. The existence of rigid massifs changed the orientations of some faults and rift belt, and also led to deformation concentrate around the massifs. The rifting and drifting of the South china Sea might be caused by slab pull from the proto South china Sea subducting toward Borneo and/or mantle flow caused by India-Asia collision.

关键词： South china Sea, rifting and drifting, clockwise rotation, analogue modeling, rigid massifs.