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Origin of the Neoproterozoic Baijianshan Banded Iron Formation at the Southeastern Margin of the tarim block in NW China:Implication for an Extremely Reducing Ocean

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Acta Geologica Sinica(English Edition) 2022年第1期96卷 208-220页

作者： HAO Xiaoshu ZHANG Chuanlin ZHANG Huichao DING Teng YE Xiantao College of Oceanography Hohai UniversityNanjing 210024China

The Neoproterozoic banded iron formations(BIFs)were closely associated with the“Snowball Earth”during the breakup of the Rodinia,thus they played an important role in our understanding of the atmospheric and oceanic oxygen levels during this *** this contribution,the Neoproterozoic(ca.737 Ma)Baijianshan BIF at Southeast tarim,northwestern China was *** is the dominated iron-species,which occurs as the lamina interbedded with *** BIF contains low concentrations of trace elements,and is depleted in light rare earth elements(LREEs)based on comparison with the Post-Archean Australian Shale(PAAS).In addition,the BIF exhibits slightly positive La-Eu anomalies,negligible Ce anomalies,insignificant Y anomalies,chondritic Y/Ho ratios(23-32),and slightly chondritic initial ε_(Nd)(t=737 Ma)values(−0.45 to 1.46,averaging 0.37).All these features indicate that the precipitation of Baijianshan BIF was closely related to the submarine low-T hydrothermal fluids with little detrital ***,the Baijianshan BIF is characterized by the significant enrichment of heavy Fe isotopes,with δ^(57)Fe_(IRMM-014) values ranging from 1.78‰ to 3.05‰,revealing the partial oxidation of Fe^(2+) into Fe^(3+) during the precipitation of this *** data suggest that the formation of Baijianshan BIF was closely associated with a significantly reducing ocean,which most likely was isolated from the oxidized atmosphere by a local ice *** Neoproterozoic Baijianshan ocean has the initial oxygen levels as low as,or even lower than that of Archean and Paleoproterozoic oceans.

关键词： Neoproterozoic banded iron formations(BIFs) Sr-Nd isotope Fe isotope tarim block

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Petrological and geochemical characteristics of mafic rocks from the Neoproterozoic Sugetbrak Formation in the northwestern tarim block,China

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China Geology 2023年第1期6卷 85-99页

作者： Hong-zhe Xie Xiang-kun Zhu Xun Wang Yuan He Wei-bing Shen MNR Key Laboratory of Isotope Geology MNR Key Laboratory of Deep-Earth DynamicsInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China

The Neoproterozoic Sugetbrak Formation in the Aksu area,which is located at the northwest margin of tarim block,comprises mafic rocks and provides key records of the evolution of the Rodinia ***,the genetic relationship among these mafic rocks exposed in different geographical sections are still *** this study,the petrology,geochemistry,and Sr-Nd-Pb isotope geochemistry of the mafic rocks exposed in the Aksu-Wushi and Yuermeinark areas have been studied in some detail along three *** authors found that the mafic rocks in these three typical sections were mainly composed of pyroxene and plagioclase,containing a small amount of Fe-Ti oxides and with typical diabasic *** the mafic rocks in this region also showed similar geochemical *** were characterised by high TiO_(2)contents(1.47%–3.59%)and low MgO(3.52%–7.88%),K_(2)O(0.12%–1.21%).Large ionic lithophile elements(LILEs)(Rb,Sr,and Cs)were significantly ***,high field strength elements(HFSEs)were relatively *** the samples,light rare earth elements(LREEs)were enriched,while heavy rare earth elements(HREEs)were *** on the Zr/Nb,Nb/Y,and Zr/TiO_(2)ratios,the Aksu mafic rocks belong to a series of sub-alkaline and alkaline transitional *** mafic rocks along the three typical sections showed similar initial values of^(87)Sr/^(86)Sr(I_(Sr))(0.7052–0.7097)and ε_(Nd)(t)(–0.70 to–5.35),while the Pb isotopic compositions with^(206)Pb/^(204)Pb,^(207)Pb/^(204)Pb and^(208)Pb/^(204)Pb values of 16.908–17.982,15.487–15.721,37.276–38.603,*** of the samples plot into the area near EM-Ⅰ,indicating that the magma of the mafic rocks might have derived from a relatively enriched mantle with some crustal materials *** geochemical element characteristics of most samples showed typical OIB-type geochemical characteristics indicating that the source region had received metasomatism of recycled *** with the

关键词： Mafic rocks Sugetbrak Formation Rodinia supercotinent Neoproterozoic Sr-Nd-Pb isotopes Mantle plume Geological survey engineering tarim block Xinjiang

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A Great late Ediacaran ice age

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National Science Review 2023年第8期10卷 105-118页

作者： Ruimin Wang Bing Shen Xianguo Lang Bin Wen Ross N. Mitchell Haoran Ma Zongjun Yin Yongbo Peng Yonggang Liu Chuanming Zhou Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education and School of Earth and Space SciencesPeking University 2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation and Institute of Sedimentary GeologyChengdu University of Technology 3. State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of Geosciences State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences School of Earth Sciences and Engineering Nanjing University State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment Chinese Academy of Sciences School of Physics Peking University

The emergence of the Ediacara biota soon after the Gaskiers glaciation ca. 580 million years ago(Ma)implies a possible glacial fuse for the evolution of animals. However, the timing of Ediacaran glaciation remains controversial because of poor age constraints on the ～30 Ediacaran glacial deposits known worldwide. In addition, paleomagnetic constraints and a lack of convincing Snowball-like cap carbonates indicate that Ediacaran glaciations likely did not occur at low latitudes. Thus, reconciling the global occurrences without global glaciation remains a paradox. Here, we report that the large amplitude, globally synchronous ca. 571–562 Ma Shuram carbon isotope excursion occurs below the Ediacaran Hankalchough glacial deposit in tarim, confirming a post-Shuram glaciation. Leveraging paleomagnetic evidence for a～90° reorientation of all continents due to true polar wander, and a non-Snowball condition that rules out low-latitude glaciations, we use paleogeographic reconstructions to further constrain glacial ages. Our results depict a ‘Great Ediacaran Glaciation’ occurring diachronously but continuously from ca.580–560 Ma as different continents migrated through polar–temperate latitudes. The succession of radiation, turnover and extinction of the Ediacara biota strongly reflects glacial–deglacial dynamics.

关键词： carbonate carbon isotopes Shuram excursion inertial interchange true polar wander (IITPW) hankalchough glaciation tarim block

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The collision between the Yili and tarim blocks of the Southwestern Altaids:Geochemical and age constraints of a leucogranite dike crosscutting the HP-LT metamorphic belt in the Chinese Tianshan Orogen

The collision between the Yili and Tarim blocks of the South...

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中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： Reiner Klemd GeoZentrum Nordbayern Universitt ErlangenSchlossgarten 5a91054 ErlangenGermany

A ca.600 m-long,0.5-20 m-wide NW-SE trending granite dike crosscuts the high pressure-low temperature (HP-LT) Tianshan metamorphic belt,the foliation of which is parallel to the main ENE regional trend in the Chinese South Tianshan *** is mainly composed of plagioclase,K-feldspar,quartz,muscovite,biotite and secondary chlorite,while fluorite,zircon and xenotime occur as *** immediate country rock is a quartz-biotite-plagioclase schist,which grades several tens of meters away from the granite dike into a chlorite-mica-albite *** latter schist is intimately intercalated with blueschist layers and *** A/CNK value of the granite dike samples varies from 1.15 to 1.27 indicating a strongly peraluminous ***/NaO ranges from 0.06 to 0.17 and AlO/TiO from 240 to 525,similar to the ratios of strongly peraluminous(SP) granites exposed in ’high-pressure’ collision zones such as the Himalayas.A zircon U-Pb age of 285 Ma was obtained for the granite dike,thus constraining the upper limit for the age of HP-LT *** petrological and geochemical data suggest that the SP leucogranite dike intruded during the exhumation of overthickened crust in the post-collisional setting between the Yili(-Central Tianshan) and tarim *** dataset presented here in conjunction with previously published data corroborate that the HP-LT metamorphism must have occurred earlier than the Permian in the Tianshan ***, the collision between the Yili(-Central Tianshan) and tarim blocks and the final amalgamation of the Southwestern Altaids must have been terminated in Late Paleozoic and not in Triassic times as previously suggested.

关键词： Leucogranite dike Collision Yili block tarim block Tianshan Southwestern Altaids

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Tectonic types and evolution of Ordovician proto-type basins in the tarim region

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Science Bulletin 2007年第S1期 164-177页

作者： HE DengFa1, ZHOU XinYuan2, ZHANG ChaoJun3 & YANG XiaoFa1 1 Energy Resources School, China University of Geosciences, Beijing 100083 2 PetroChina tarim Oilfield Company, Korla 841000, China 3 Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China

The Ordovician system is an important target for exploration in the tarim Basin. Restoration of the Ordovician tectono-depositional environment is a key basis for the study of the structural development history in tarim block and the prediction of the favorable Ordovician reservoir belts (zones). Based on the surrounding tectonic settings, the litho-facies and sedimentary fill, the palaeo-geography, palaeoclimate and palaeo-ecology, and the structural deformation and magmatic eruptions, in this paper we combine the sedimentary fill in the basin with the development of the surrounding orogenic belts and re-build the proto-type basins of the different Ordovician periods. During the Ordovician period, the tarim region was characterized by the composite of the interior cratonic depression with the peripheral cratonic depression. The interior cratonic depression in the central and western parts is mainly the depositional area of the platform facies while the peripheral cratonic depression in the eastern part is mainly the zone of deepwater basin facies, with the slope acting as the transition belt between them. During the Late Ordovician period, the closure of the Northern Kunlun Ocean and destruction of the trencharc-basin system in the Altyn Tagh region put the southern part of the tarim block under compression and uplifting and turned the central and western parts of the carbonate platform into the mixed depositional continental shelf. The eastern region of the basin had the over-compensated flysch sedimentation with huge thickness, marking the drastic turn of the basin nature. The basin tectonic framework turned to the south-north differentiation of the Silurian period from the east-west differentiation of the Ordovician period.

关键词： Ordovician period proto-type basin composite basin basin evolution tarim block

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A Middle Ordovician reef complex on the carbonate ramp of the NW tarim,NW China

A Middle Ordovician reef complex on the carbonate ramp of th...

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2015年全国沉积学大会

作者： Jianpo Wang Yue Li Yuanyuan Zhang Wuhan Center of Geological Survey Nanjing Institute of Geology and Palaeontology

Ordovician carbonates are well outcropped along the Lianglitag Mountains with distance about 35 km in Bachu County, NW tarim. It was an epicontinental sea closed to the northwest margin of the Central tarim Uplift palaeogeographically. Darriwilian(upper Middle Ordovician) Yijianfang Formation is about 70 meters in thickness completely composed of shallow marine limestones. Patch reefal and biostromal units constructed dominantly by Calathiμm from the middle member of the formation are respectively concentrated from northern and southern regions along the Lianglitag Mountains. Bigger patch reefs more than 10 m in thicknesses and 50 m in diameters are prevailed in the northern region. Some of them are stacked by smaller mounds inserted by bioclastic units. Reef-attached shelly fauna are diverse identified as elements such as trilobites, nautiluses, bivalves, brachiopods etc.. Dilapidated Calathiμm together with coarse organism fragments illustrate a high-energy belt. The sizes of patch reefs are gradually shrinkable to meters in thicknesses and weak relieves southward. Coeval autobiostrome formed by in situ Calathiμm frameworks baffling matrixes is only about 3 m in thickness at the southernmost section. Other shelly elements are quite low both in diversity and abundance herein. It was likely to be a calmer environment favorably of a back reef setting. Moreover, the sedimentary unit equivalent to the Yijianfang Formation is completely lacked toward the southern Mazatag Well block, where was an oldland exposed above the sea-level during this time-interval. Therefore, such ecologicl, morphological and taphonomicdifferentiations of subfacies on the carbonate ramp enhances a reef complex with more turbulence leeward from the northern region and calmer back reef belt southward. The northern margin of the carbonate ramp further extends to the Yangjikan section of Kelpin County. The Darriwilian graptolitic black shales of the Sargan Formation were formed in typical stagnated

关键词： Calathiμm reef complex Yijianfang Formation Middle Ordovician tarim block NW China

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