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| 1 | Geochemical changes across the Ordovician-Silurian transition on the Yangtze Platform,South China显示文摘The trace element and rare earth element(REE) variations across the Ordovician-Silurian succession are presented from two outcrop sections on the Yangtze Platform:the Nanbazi section,Guizhou Province,deposited in a shallow platform interior setting,and the Wangjiawan section,Hubei Province,deposited in a deeper basinal environment.Geochemical analysis of closely spaced samples through three intervals,the Wufeng,Guanyinqiao and Longmaxi,revealed vast palaeoceanographic changes.Some geochemical proxies,including Th/U,Ni/Co,V/Cr,and V/(V+Ni) ratios,together with sedimentary facies and biotic data,indicate that an anoxic condition on the most of the Yangtze Platform during the Wufeng and Longmaxi intervals,but an oxic condition during the Guanyinqiao time.The shift of the anoxic to the oxic environment during the Guanyinqiao time coincided with a global sea-level lowstand,in parallel with the global glaciation.The Longmaxian anoxic environment was a result of a global sea-level rise,which may be synchronized with a mainly catastrophic event in the latest Ordovician.Although the two sections generally show similar variation patterns of trace and REE concentrations and some element ratios,a minor difference occurs between the Wangjiawan and Nanbazi sections,likely reflecting a difference in depositional setting during the accumulation.Such an oceanic oxygen-level variation may add a useful constraint to the current arguments on the cause and consequence of the latest Ordovician mass extinction. | YAN DeTian CHEN DaiZhao WANG QingChen WANG JianGuo | 2009 | Science China Earth Sciences2009，52，1： | 17 |
| 2 | In situ stable isotopic constraints on dolomitizing fluids for the hydrothermally-originated saddle dolomites at Keping, Tarim Basin显示文摘Detailed characterization of diagenetic fluid behaviour and evolution is commonly hindered by shortage of appropriate and economic methods to carry out in situ analysis in the tiny diagenetic mineral crystals. Using micromill sampling method, this study presents in situ stable isotopic data for the growth zones of saddle dolomite crystals in the hydrothermally-altered dolostones of Upper Cambrian (Furongian) at Keping, Tarim Basin, NW China. These data show minor and large variations in δ13C ( 0.7‰ to 1.5‰ VPDB) and δ18O ( 8.3‰ to 13.8‰ VPDB), respectively, from the cores to outer rims of the dolomite crystals and suggest that saddle dolomites precipitated from dolomitizing fluids with similar carbon sources but oscillatory temperatures during different formation stages. This scenario is confirmed by microthermometry of fluid inclusions within the growth zones of dolomite crystals. This study indicates that in situ isotope analysis could provide more detailed information related to the source and pathway of dolomitizing fluids, facilitating better characterization of dolomitizing fluids and processes. | DONG ShaoFeng CHEN DaiZhao QING HaiRuo JIANG MaoSheng ZHOU XiQiang | 2013 | Chinese Science Bulletin2013，58，23： | 9 |
| 3 | Discovery of the Jiawengmen Stromatolite Assemblage in the Southern Belt of Eastern Kunlun, NW China and Its Significance显示文摘This paper reports a newly discovered Late Mesoproterozoic–Early Neoproterozoic stromatolite assemblage, named here the “Jiawengmen stromatolite assemblage”, represented by a Conophyton-Baicalia association in the Jiawenmen area in the southern belt of the Eastern Kunlun. This stromatolite assemblage is dominated by large-scale conical stromatolites and related elements, i.e., Conophyton garganicus var. inkeni, C. cf. ressoti Menchikov, Jacutophyton cf., Conicodomenia f., which commonly co-exist with elements of the group of Baicalia. This assemblage can be correlated with that of the middle Jixian-middle Qingbaikou System in North and Northwest China, but is different from that in South China. Correlation can also be made with that in the upper horizon of the Middle Riphean-lower horizon of the Upper Riphean in the South Ural Mountains and Siberia of Russia, in North Africa, and in the Alaskan Peninsula of North America. These facts suggest that the Jiawengmen stromatolite assemblage probably colonized during 1300–850 Ma ago. Accordingly, the stromatolite-bearing carbonate rocks are then proposed to correspond to the middle Jixian System-middle Qingbaikou System or the upper Middle Riphean-lower Upper Riphean. Our stromatolite data further suggest that a Precambrian microblock, named the Xialawen microblock here, occurred in the southern belt of Eastern Kunlun, the western part of the Maqên microblock. Similar stromatolite assemblages in the Maqên microblock and those blocks that occurred in North China, Siberia and North Africa point to similar paleogeographic and paleoenvironmental conditions. These microblock and blocks were probably located at low latitudes and on the continental margins of the Rodinian supercontinent, where warm epicontinental seas were favorable to widespread colonization of stromatolites during the Late Mesoproterozoic-Early Neoproterozoic. However, these stromatolite assemblages are quite different from those of the South China block, which is suggestive of different paleogeographic contexts, and probably also of a different tectonic affinity. | BIAN Qiantao ZHU Shixing I. I. POSPELOV M. A. SEMIKHATOV SUN Shufen CHEN Daizhao NA Chunguang | 2005 | Acta Geologica Sinica(English Edition)2005，79，4： | 5 |
| 4 | End-Guadalupian mass extinction and negative carbon isotope excursion at Xiaojiaba,Guangyuan,Sichuan显示文摘The end-Paleozoic biotic crisis is characterized by two-phase mass extinctions;the first strike,resulting in a large decline of sessile benthos in shallow marine environments,occurred at the end-Guadalupian time.In order to explore the mechanism of organisms' demise,detailed analyses of depositional facies,fossil record,and carbonate carbon isotopic variations were carried out on a Maokou-Wujiaping boundary succession in northwestern Sichuan,SW China.Our data reveal a negative carbon isotopic excursion across the boundary;the gradual excursion with relatively low amplitude(2.15‰) favors a long-term influx of isotopically light 12 C sourced by the Emeishan basalt trap,rather than by rapid releasing of gas hydrate.The temporal coincidence of the beginning of accelerated negative carbon isotopic excursion with onsets of sea-level fall and massive biotic demise suggests a cause-effect link between them.Intensive volcanic activity of the Emeishan trap and sea-level fall could have resulted in detrimental environmental stresses and habitat loss for organisms,particularly for those benthic dwellers,leading to their subsequent massive extinction. | WEI HengYe CHEN DaiZhao YU Hao WANG JianGuo | 2012 | Science China Earth Sciences2012，55，9： | 5 |
| 5 | Characteristics and Dolomitization of Upper Cambrian to Lower Ordovician Dolomite from Outcrop in Keping Uplift, Western Tarim Basin, Northwest China显示文摘Late Cambrian to Early Ordovician sedimentary rocks in the western Tarim Basin, Northwest China, are composed of shallow-marine platform carbonates. The Keping Uplift is located in the northwest region of this basin. On the basis of petrographic and geochemical features, four matrix replacement dolomites and one type of cement dolomite are identified. Matrix replacement dolomites include (1) micritic dolomites (MD1); (2) fine-coarse euhedral floating dolomites (MD2); (3) fine-coarse euhedral dolomites (MD3); and (4) medium-very coarse anhedral mosaic dolomites (MD4). Dolomite cement occurs in minor amounts as coarse saddle dolomite cement (CD1) that mostly fills vugs and fractures in the matrix dolomites. These matrix dolomites have δ18O values of ?9.7‰ to ?3.0‰ VPDB (Vienna Pee Dee Belemnite); δ13C values of ?0.8‰ to 3.5‰ VPDB; 87Sr/86Sr ratios of 0.708516 to 0.709643; Sr concentrations of 50 to 257 ppm; Fe contents of 425 to 16878 ppm; and Mn contents of 28 to 144 ppm. Petrographic and geochemical data suggest that the matrix replacement dolomites were likely formed by normal and evaporative seawater in early stages prior to chemical compaction at shallow burial depths. Compared with matrix dolomites, dolomite cement yields lower δ18O values (?12.9‰ to ?9.1‰ VPDB); slightly lower δ13C values (?1.6‰-0.6‰ VPDB); higher 87Sr/86Sr ratios (0.709165-0.709764); and high homogenization temperature (Th) values (98°C-225°C) and salinities (6 wt%-24 wt% NaCl equivalent). Limited data from dolomite cement shows a low Sr concentration (58.6 ppm) and high Fe and Mn contents (1233 and 1250 ppm, respectively). These data imply that the dolomite cement precipitated from higher temperature hydrothermal salinity fluids. These fluids could be related to widespread igneous activities in the Tarim Basin occurring during Permian time when the host dolostones were deeply buried. Faults likely acted as important conduits that channeled dolomitizing fluids from the underlying strata into the basal carbonates, leading to intense dolomitization. Therefore, dolomitization, in the Keping Uplift area is likely related to evaporated seawater via seepage reflux in addition to burial processes and hydrothermal fluids. | JI Congwei QING Hairuo CHEN Daizhao LUO Ping JIN Zhijun SHAO Longyi | 2013 | Acta Geologica Sinica(English Edition)2013，87，4： | 4 |
| 6 | The origin of bedding-parallel fibrous calcite veins in the Lower Permian Chihsia Formation in western Hubei Province,South China显示文摘Bedding-parallel fibrous veins occurring as lenticular to flattened intercalations were found in the organic-rich marlstone/calcareous shale of the upper Lower Permian Chihsia Formation in western Hubei Province,South China. They dominantly consist of fibrous calcite crystals with smooth and tight boundaries, forming fencelike inward, syntaxial growth clusters toward the vein center along which a median suture line generally occurs.Petrographic evidence indicates that these veins may form at relatively shallow burial depth, where fluid overpressures would have incrementally created the bed-parallel vein space, resulting in displacive growth of fibrous calcite.On the other hand, the C, O and S isotopic data across the vein reveal slightly depleted d13Ccarbvalues(-3.32 % to +0.19 % VPDB) and moderately depleted d18Ocarbvalues(-9.6 % to-7.3 % VPDB) with respect to those of coeval seawaters and slightly heavier d34Spyritevalues(-7.88 % CDT) with respect to those of ambient rocks.Stable isotope evidence consistently suggests significant contribution of bacterial sulfate reduction(BSR) to the formation of the fibrous calcite cements in the vein. The BSR could have been intensive with the availabilities of residual sulfate and abundant organic matters in theChihsia sediments during shallow burial, increasing the alkalinity of pore waters and further promoting carbonate precipitation. Thus, the bedding-parallel fibrous calcite vein in the upper Lower Permian Chihsia Formation is an important time-specific petrographic capsule, providing clues for understanding the diagenetic process in organicrich sediments. | Hao Yu Xiqiang Zhou Jianguo Wang Chuan Guo Hengye Wei Daizhao Chen | 2015 | Science Bulletin2015，60，20： | 4 |
| 7 | Early dolomitisation of the Lower-Middle Ordovician cyclic carbonates in northern Tarim Basin, NW China显示文摘High-frequency metre-scale cycles are present within the Lower-Middle Ordovician carbonate successions in northern Tarim Basin, NW China. These metre-scale cycles were variably dolomitised from top to bottom. Three types of replacive dolomites were recognised, including dololaminite(very finely to finely crystalline, planar-s to nonplanar-a dolomite;type-1), patterned dolomite(finely crystalline, planar-s dolomite; type-2), and mottled dolomite(finely to medium crystalline,nonplanar-a(s) dolomite; type-3). Petrographic evidence indicate these dolomites were primarily deposited in supratidal to restricted subtidal environments, and formed in near-surface to shallow burial realms. Geochemically, all types of dolomites have similar δ13C and 87Sr/86 Sr ratios comparable to calcite precipitated in equilibrium with the Early-Middle Ordovician seawater. These geochemical attributes indicate that these dolomites were genetically associated and likely formed from connate seawater-derived brines. Of these, type-1 dolomite has δ18O values(.4.97‰ to.4.04‰ VPDB) slightly higher than those of normal seawater dolomite of the Early-Middle Ordovician age. Considering the absence of associated evaporites within type-1 dolomite, its parental fluids were likely represented by slightly evaporated(i.e., mesosaline to penesaline) seawater with salinity below that of gypsum precipitation. More depleted δ18O values(.7.74‰ to.5.20‰ VPDB) of type-2 dolomite and its stratigraphic position below type-1 dolomite indicate the generation of this dolomite from mesosaline to penesaline brines at higher temperatures in near-surface to shallow burial domains. Type-3 dolomite yields the most depleted δ18O values(–9.30‰to –7.28‰ VPDB), pointing to that it was most likely formed from coeval seawater-derived brines at highest temperatures in a shallow burial setting. There is a downward decreasing trend in δ18O values from type-1 through type-2 to type-3 dolomites, and in abundance of dolomites, indicating that the dolomitising fluids probably migrated downward from above and persisted into shallow burial conditions. | GUO Chuan CHEN DaiZhao DONG ShaoFeng QIAN YiXiong LIU CunGe | 2017 | Science China Earth Sciences2017，60，7： | 3 |
| 8 | Environmental Redox Changes of the Ancient Sea in the Yangtze Area during the Ordo-Silurian Transition显示文摘摘要:广泛有机物(OM ) 富有的外形(黑页岩) 在 Yangtze 区域发生在 Ordo 志留纪边界继任,华南。为了在 Ordo 志留纪期间调查 Yangtze 海的氧化还原作用变化,转移,二 OM 节(在在 Zhangjiajie 的 Yichang,湖北省,和 Sanjiaguan 的 Wangjiawan,湖南省) 跨骑 Ordo 志留纪边界被学习。在这研究完成的大小包括总数的内容 Fe 的器官的碳( TOC ),黄铁矿硫,和不同种类,包括dithionite可引出的 Fe (喂),黄铁矿 Fe ( FeP ),HCI可引出的 Fe ( FeH ),和全部的 Fe ( FeT )在黑页岩,象另外的氧化还原作用代理一样,例如 S/C 比率,在高度反应的 Fe 之间的比率( FeHR =喂了+ FeP )并且 FeT ,和Fep/(FeP + FeH )比率,作为 pyritization ( DOP )的度知道。在 Wangjiawan 节,中间的 Ashgill 沉积有高 FeHR/FeT 比率(0.20-0.77;avg。0.45 ) ,高 DOP 价值(0.21-0.72;avg。0.54 ) ,并且器官的碳内容的一个相对经常的硫内容独立人士。由对比,中间早, Hirnantian 存款通常有低 FeHR/FeT 比率(0.10-0.35;avg。0.21 ) ,低 DOP 价值(0.11-0.40;avg。0.28 ) ,并且 S/C 价值在正常海洋的价值上正在聚类(S/C = 0.36 ) 。迟了的 Hirnantian 和早 Rhuddanian 存款,类似于那些中间的 Ashgill 存款,被高 FeHR/FeT 比率描绘(0.32-0.49;avg。0.41 ) ,高 DOP 价值(0.46-0.68;avg。0.53 ) 并且相当经常的硫内容。这些数据在间隔期间在 Yangtze 海架上建议海洋的血缺氧的出现中间的 Ashgill,迟了的 Hirnantian 和早 Rhuddanian,和通气并且氧化的水兵调节在期间中间早 Hirnantian 时间。中间早, Hirnantian 通气了事件是有全球冰川的经期的伴随物,多半在架海床之上源于 glacio 海面升降的海平面的秋天和冷、稠密的氧化的水的随后的循环。因此,突然的变化从从迟了的 Hirnantian 氧化了到缺氧的海洋的水,早 Rhuddanian 从海面升降的海水平的冰期后的上升被结果。在 subemergent 高地附近从 Sanjiaguan 节与数据结合了,水列的咸度层化被很低的 S/C 比率强烈证实(0.00-0.08, avg。0.02 ) ,低 FeHR/FeT 比率(0.10-0.37, avg。0.27 ) ,低 DOP 价值(0.01-0.27, avg。0.10 ) ,并且 TOC 内容(0.72%-4.27% , avg。2.55%) 。在这种情形下面,缺氧的水列能在 halocline,脱盐的水在上面形成了下面形成了。在 Wangjiawan 节, TOC 内容通常高(0.94-9.32% , avg。4.44%) ,但是低(0.35%-2.12% , avg。1.29%) 在里面中间早,与海洋的 oxic 阶段是重合的和到 stratal 厚度的器官的内容的关系,建议有机物的累积被氧主要控制的 Hirnantian 水列铺平;在另一方面,生产率和 depositional 率可能也在器官的累积和保藏起了一个作用。 | YAN Detian CHEN Daizhao WANG Qingchen WANG Jianguo CHU Yang | 2008 | Acta Geologica Sinica(English Edition)2008，82，3： | 3 |
| 9 | SIMS U-Pb Zircon Geochronological and Carbon Isotope Chemostratigraphic Constraints on the Ediacaran-Cambrian Boundary Succession in the Three Gorges Area, South China显示文摘The Ediacaran–Cambrian succession in South China records dramatic biological,oceanic and geochemical changes,but it is not well constrained geochronologically.This study reports a new SIMS U-Pb date of 543.4±3.5 Ma(MSWD=1.2)from a tuffaceous layer in the Zhoujiaao Section,and carbonate C-O isotopes in both Zhoujiaao and Sixi sections,Three Gorges area.This tuffaceous layer is present in the Upper Dengying Formation(i.e.,the Baimatuo Member)which is characterized by a stableδ13Ccarb plateau and the beginning of a negativeδ13Ccarb shift near its upper boundary.In accordance with the existing biostratigraphic and chemostratigraphic data,this new date corroborates that the upper boundary of the Dengying Formation in South China is approximately equivalent to the Ediacaran-Cambrian boundary(ca.541 Ma).This age also provides the minimum age of the last appearance of the Shibantan biota in the Three Gorges area,indicating that the terminal Ediacaran index fossils(e.g.,Cloudina,Sinotubulites)are not reliable stratigraphic markers for further subdivision of the uppermost Ediacaran. | Taiyu Huangc Daizhao Chen Yi Ding Xiqiang Zhou Gongjing Zhang | 2020 | Journal of Earth Science2020，31，1： | 2 |
| 10 | Evo- lution from an anoxic to oxic deep ocean during the Ediaca- ran-Cambrian transition and implications for bioradiation 显示文摘 | WANG Jianguo CHEN Daizhao YAN Detian | 2012 | Chemical Geology2012，，306307： | 1 |
| 11 | Paired δ^13Ccarb-δ^13Corg Evolution of the Dengying Formation from Northeastern Guizhou and Implications for Stratigraphic Correlation and the Late Ediacaran Carbon Cycle显示文摘This study provides δ^13C profiles from a lower-slope(Well ZK102)to basin(Bahuang Section)environment to better understand the temporal and spatial variability in δ^13Ccarb-δ^13Corg of the Yangtze Block during the Late Ediacaran.Our new δ^13C profiles together with the reported data suggest that the Upper Ediacaran successions from different depositional environments are generally bounded by negative δ^13Ccarb and/or δ^13Corg excursions in the underlying and overlying strata.Moreover,the Upper Ediacaran δ^13Ccarb profiles generally can be subdivided into two positive excursions and an interjacent negative excursion,whereas the paired δ^13Corg profiles from different depositional environments have individual variation trends.On the other hand,these data show a large surface-to-deep waterδ^13C gradient(~5‰variation in δ^13Ccarb,>10‰variation in δ^13Corg)which can be reasonably explained by the heterogeneity of the biological activities in the redox-stratified water column.Furthermore,the decoupled δ^13Ccarb-δ^13Corg pattern with large δ^13Corg perturbations at the lower slope precluded the existence of a large dissolved organic carbon reservoir at the Yangtze Block during the Late Ediacaran.Thus,the high δ^13Ccarb values in the Upper Ediacaran succession could be balanced by large amounts of buried organic carbon likely associated with high productivity. | Yi Ding Daizhao Chen Xiqiang Zhou Taiyu Huang Chuan Guo Rumana Yeasmin | 2020 | Journal of Earth Science2020，31，2： | 1 |
| 12 | Long-distance correlation between tectonic-controlled, iso- lated carbonate platforms by cyclostratigraphy and sequence stratigraphy in the Devonian of South China 显示文摘 | Chen Daizhao Tucker M E Jiang Maosheng Zhu Jingquan | 2001 | Sedimentol- ogy2001，48，1： | 1 |
| 13 | The Frasnian-Famennian mass extinction: Insights from high-resolution sequence stratigraphy and cyclostratigraphy in South China显示文摘 | CHEN Daizhao TUCKER M E | 2003 | Palaeogeography Palaeoclimatology Palaeoecology2003，193，： | 1 |
| 14 | Multistage hydrothermal dolomites in the Middle Devonian (Givetian)carbonates from the Guilin area,South China显示文摘 | CHEN Daizhao QING Hairuo YANG Chao | 2004 | Sedimentology2004，51，： | 1 |
| 15 | Source-controlled carbonates in a small Eocene half-graben lake basin (Shulu Sag)in central Hebei Province,North China显示文摘 | Jiang Zaixing Chen Daizhao Qiu Longwei | 2007 | Sedimentology2007，54，2： | 1 |
| 16 | Source-controlled carbonates in a small Eocene half-graben lake basin (Shulu sag)in central Hebei Province,North China显示文摘 | Jiang Zaixing Chen Daizhao Qiu Longwei | 2007 | Sedimentology2007，54，2： | 1 |
| 17 | Hydrothermal venting and basin evolution (Devonian, South China): Constraints from rare earth dement geochemistry of chert 显示文摘 | Chen Daizhao Qing Hairuo Yah Xin | 2006 | Sedimentary Geology2006，183，34： | 1 |
| 18 | Hydrothermal venting and basin evolution (Devonian, South China): Constraints from rare earth element geochemistry of chert 显示文摘 | Chen Daizhao Qing Hairuo Yan Xin | 2006 | Sedimentary Geology2006，183，34： | 1 |
| 19 | Source-controlled carbonates in a small Eocene half-graben lake basin (Shulu sag)in central Hebei Province,North China显示文摘 | Jiang Zaixing Chen Daizhao Qiu Longwei | 2007 | Sedimentology2007，54，2： | 1 |
| 20 | Hydrotherma venting and basin evolution ( Devonian, South China) : Con straints from rare earth element geochemistry of chert显示文摘 | Daizhao Chen Hairou Qing Xin Yan | 2006 | Sedimentary Geology2006，183，： | 1 |
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