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Sedimentary Features and Implications for the Precambrian Non-stromatolitic Carbonate Succession:A Case Study of the Mesoproterozoic Gaoyuzhuang Formation at the Qiangou Section in Yanqing County of Beijing

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Acta Geologica Sinica(English Edition) 2008年第2期82卷 295-309页

作者： mei mingxiang State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 School of Earth Sciences and Resources China University of Geosciences Beijing 100083

In the long Precambrian period, stromatolitic carbonate successions were very common. However, the non-stromatolitic carbonate succession that is marked by subtidal deposits shows a sharp contrast to the stromatolitic carbonate succession. Both the non-stromatolitic and the stromatolitic carbonate successions are important clues for the further understanding of the evolving carbonate world of the Precambrian. The Mesoproterozoic Gaoyuzhuang Formation at the Qiangou section in northwestern suburb of Beijing is a set of more than 1000 m-thick carbonate strata that can be divided into four members （or subformations）, in which a non-stromatolitic carbonate succession marked by the scarcity of stromatolites makes up the third member of the formation. This non-stromatolitic carbonate succession can further be subdivided into three third-order sequences that are marked by the regular succession of sedimentary facies. In third-order sequences, a lot of subtidal carbonate meter-scale cycles made up of medium-bedded leiolite limestones and thin-bedded marls constitute their transgressive system tracts （TSTs） and the early high-stand system tracts （EHSTs）, a lot of meter- scale cycles made up by thin-bedded limestones and marls constitute their condensed sections （CSs）, and thick-bedded to massive dolomitic limestones or lime dolomites make up the late high-stand system tracts （LHSTs）. The particularly non-stromatolitic carbonate succession making up the third member of the Mesoproterozoic Gaoyuzhuang Formation at the Qiangou section might be the representative of the non-stromatolitic carbonate succession of the Precambrian because of its special lithological features and particular sedimentary structures, and its general sedimentary features are helpful and meaningful for the further understanding of the evolution rules of the sophisticate and evolving carbonate world of the Precambrian. The time scale of the Gaoyuzhuang Formation is deduced as that from 1600 Ma to 1400 Ma;

关键词： non-stromatolitic carbonate succession Gaoyuzhuang Formation Mesoproterozoic,Qiangou section in Yanqing

The Late Triassic Sequence-Stratigraphic Framework of the Upper Yangtze Region,South China

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Acta Geologica Sinica(English Edition) 2017年第1期91卷 51-75页

作者： mei mingxiang LIU Shaofeng School of Earth Sciences and Resources China University of Geosciences

In the transitional period between the Middle and the Late Triassic, the Indochina orogeny caused two tectonic events in South China:(1) the formation and uplift of the Qinling-Dabie orogenic belt along the northern margin of the South China Plate, due to its collision with the North China Plate; and 2) the development of a 1300-km-wide intra-continental orogen in the southeastern part of the South China Plate, which led to a northwestward movement of the foreland thrust-fold zone. These tectonic events resulted in the ending of the Yangtze Platform, and were a stable paleogeographic factor from the Eidacaran to the end of the Middle Triassic. This platform was characterized by the widespread development of shallow-water carbonates. After the end of the Yangtze Platform, the upper Yangtze foreland basin(or Sichuan foreland basin) was formed during the Late Triassic and became a accumulation site of fluvial deposits that are composed of related strata of the Xujiahe Formation. In western Sichuan Province, the Xujiahe Formation overlies the Maantang Formation shallow-water carbonate rocks of the Xiaotangzi Formation siliciclastic rocks(from shelf shales to littoral facies). The sequence-stratigraphic framework of the Upper Triassic in the upper Yangtze foreland basin indicates a particular alluvial architecture, characterized by sequences composed of(1) successions of low-energy fluvial deposits of high-accommodation phases, including coal seams, and(2) high-energy fluvial deposits of low-accommodation phases, including amalgamated river-channel sandstones. The spatial distribution of these fluvial deposits belonging to the Xujiahe Formation and its relative strata is characterized by gradual thinning-out, overlapping, and pinching-out toward both the east and south. This sedimentary record therefore expresses a particular sequence-stratigraphic succession of fluvial deposits within the filling succession of the foreland basin. The sequence-stratigraphic framework for

关键词： Late Triassic sequence-stratigraphic framework upper Yangtze foreland basin upper Yangtze region South China

A New Progress of the Proterozoic Chronostratigraphical Division

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Acta Geologica Sinica(English Edition) 2016年第4期90卷 1097-1121页

作者： mei mingxiang Kyawt Kay KHAING School of Earth Sciences and Resources China University of Geosciences

The Precambrian, an informal chronostratigraphical unit, represents the period of Earth history from the start of the Cambrian at ca. 541 Ma back to the formation of the planet at 4567 Ma. It was originally conceptualized as a ＂Cryptozoic Eon＂ that was contrasted with the Phanerozoic Eon from the Cambrian to the Quaternary, which is now known as the Precambrian and can be subdivided into three eons, i.e., the Hadean, the Archean and the Proterozoic. The Precambrian is currently divided chronometrically into convenient boundaries, including for the establishment of the Proterozoic periods that were chosen to reflect large-scale tectonic or sedimentary features （except for the Ediacaran Period）. This chronometric arrangement might represent the second progress on the study of chronostratigraphy of the Precambrian after its separation from the Phanerozoic. Upon further study of the evolutionary history of the Precambrian Earth, applying new geodynamic and geobiological knowledge and information, a revised division of Precambrian time has led to the third conceptual progress on the study of Precambrian chronostratigraphy. In the current scheme, the Proterozoic Eon began at 2500 Ma, which is the approximate time by which most granite-greenstone crust had formed, and can be subdivided into ten periods of typically 200 Ma duration grouped into three eras （except for the Ediacaran Period）. Within this current scheme, the Ediacaran Period was ratified in 2004, the first period-level addition to the geologic time scale in more than a century, an important advancement in stratigraphy. There are two main problems in the current scheme of Proterozoic chrouostratigraphical division：（1） the definition of the Archean-Proterozoic boundary at 2500 Ma, which does not reflect a unique time of synchronous global change in tectonic style and does not correspond with a major change in lithology; （2） the round number subdivision of the Proterozoic into several periods based on broad oroge

关键词： Precambrian Proterozoic Eon chronostratigraphy new progress

Giant Induan oolite:A case study from the Lower Triassic Daye Formation in the western Hubei Province,South China

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Geoscience Frontiers 2012年第6期3卷 843-851页

作者： mingxiang mei Jinhan Gao State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China

Most Phanerozoic oolites are marked by ooids with a diameter less than 2 mm. Observations on a Neoproterozoic oolite have resulted in a change of concept. The term ＂pisolite＂ that traditionally referred to oolites with a grain size of more than 2 ram, is now restricted to those coated carbonate grains formed by meteoritic freshwater diagenesis; oolites with a grain size of more than 2 mm are now defined as ＂giant＂. Particular unusual giant oolites within a set of oolitic-bank limestones with thicknesses of more than 40 m in the top part of the Lower Triassic （Induan） Daye （Ruiping） Formation at the Lichuan section in the western part of Hubei Province in South China, represent an important sedimentological phenomenon in both the specific geological period and the geological setting that is related to the end-Permian biological mass extinction. Like the giant oolites of the Neoproterozoic that represent deposits where oolites formed in a vast low-angle carbonate ramp at that special geological period, the Triassic Daye Formation at the study section are significant because they provide a comparative example to help understand the evolving carbonate world reflected by oolites, the origin of which is still uncertain, and they give insight into the sedimentation pattern of the desolate sea floor, which resulted from the mass extinction at the turn of the Permian into the Triassic.

关键词： Carbonate sedimentology Oolite diversity Triassic Induan Hubei Province South China

Sequence-stratigraphic frameworks and their palaeogeographic patterns for the Permian Lopingian of the Dianqiangui Basin and its adjacent areas of Southwestern China

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Science China Earth Sciences 2007年第6期50卷 869-885页

作者： mei mingxiang MA YongSheng DENG Jun CHU HanMin ZHENG KuanBing State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China

The Permian Lopingian in the Dianqiangui Basin and its adjacent areas is marked by the coal measures of the Wuchiapingian and the carbonate strata of the Changhsingian stages. For the Lopingian of the Dianqiangui Basin and its adjacent areas,the diversity of sedimentary facies and the obviousness of facies change provide an advantaged condition on a study of sequence stratigraphy. Approximately,the Wuchiapingian stage constitutes a third-order sequence and the Changhsingian stage forms an-other. For the Wuchiapingian stage in the study area,coal-measures were developed on the attached platform and,in addition,a special coal-measure that is composed of both limestone beds and coal beds was also developed in the central part of some isolated platforms. Grain-bank grainstones and packstones were formed on the margin of the attached platform as well as in the windward part of iso-lated platforms. For the Changhsingian stage in the study area,open-platform limestones were formed on the attached platform,while sponge-reef limestones were developed both on the margin of the at-tached platform and on the isolated platforms. The Lopingian Series is a set of basin-facies muddy shales with interbeds of silicalites in the inter-platform basin,which appears a set of the large-thick coarse clastic strata of molasses covering direct the deep-water strata from the Devonian to the Per-mian Yangsingian in the Qinzhou-Fangcheng region in the southern part of the study area. All of these features indicate the complexity of temporal-spatial facies-changes. Sequence-stratigraphic frame-works could be established,which would illustrate two types of facies-changing surfaces and dia-chronisms in the stratigraphic records,based on the combination of both biostratigraphic and chronostratigraphic materials and the regularity reflected by temporal evolutionary succession of sediments as well as spatial distributional patterns of sedimentary facies. Ultimately,features of sedi-mentary succession

关键词： sequence-stratigraphic frameworks palaeogeographical patterns the Permian Lopingian the Dianqiangui Basin and its adjacent areas

Sedimentary Features and Their Implications of Microdigital Stromatolites from the Mesoproterozoic Wumishan Formation at the Jixian Section in North China

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Acta Geologica Sinica(English Edition) 2010年第3期84卷 483-496页

作者： mei mingxiang GAO Jinhan MENG Qingfen LIU Zhirong State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China

The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3000-m-thick stromatolitic carbonate *** this succession,several lithofacies units,that is,the subtidal stromatolitic biostrome,the thrombolitic bioherm,tidal-flat micritic dolomite and lagoon dolomitic shale,make up many meter-scale cycles of the peritidal carbonate type that have been nominated as the Wumishan ***,many microdigital stromatolites make up the stromatolitic biostrome unit of the Wumishan cycles in the lower part of the Wumishan Formation. These microdigital stromatolites have been grouped as a stromatolitic assemblage by paleontologists, that is,＂Pseudogymnosolen mopanyuensis-Scuphus-Yangzhuang columnaris＂*** microdigital stromatolites had also been interpreted as the aragonite（tufa） sea-floor precipitates by sedimentologists,and has further been thought as the special products of the transitional period from the sea-floor aragonite precipitates of the Archean to the clastic and muddy carbonates of the *** there are some restrictions for the stratigraphic meaning of the concept of the stromatolitic assemblage,detailed studies on classification by paleontologists provide an important clue to understand the sedimentological meaning of the microdigital ***,an important and obvious horizon for the end of the microdigital stromatolites was recorded in the Mesoproterozoic Wumishan Formation at the Jixian section,which provides useful information to understand the stromatolite decline occurred at c.1250 Ma and the evolving carbonate world of the Precambrian.

关键词： microdigital stromatolites stromatolite decline Wumishan Formation Mesoproterozoic,Jixian in Tianjin

Milankovitch-driven cycles in the Precambrian of China:The Wumishan Formation

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Journal of Palaeogeography 2013年第4期2卷 369-389页

作者： mei mingxiang Maurice E. Tucker State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences (Beijing) Department of Earth Sciences University of Durham

Carbonate strata of the Mesoproterozoic Wumishan Formation in the Jixian area near Tianjin are ~3300 m thick and were deposited over some 100 million years(from ~1310±20 Ma to ~1207±10 Ma).Metre-scale cycles(parasequences) dominate the *** are generally of the peritidal carbonate type,and mostly show an approximately symmetrical lithofacies succession with thick stromatolite biostromes and small thromboliteoncolite bioherms constituting the central part and tidal-flat dolomites forming the upper and lower ***-supratidal dolomitic shales with palaeosol caps make up the topmost *** boundaries of the Wumishan cycles are typically exposure surfaces,and there is abundant evidence for fresh-water *** 1:4 stacking patterns indicate that the individual Wumishan cycles are sixthorder parasequences,with 4 parasequences constituting one fifth-order parasequence ***,5-8 beds or couplets,can be discerned in some of the *** regular vertical stacking pattern of beds within the sixth-order parasequences,forming the fifth-order parasequence sets,are interpreted as the result of environmental fluctuations controlled by Milankovitch rhythms,namely the superimposition of precession,and short and *** widespread 1:4 stacking pattern in the cyclic succession,as well as the local 1:5-8 stacking patterns of the beds within the cycles,suggest that the Milankovitch rhythms had similar ratios in the Mesoproterozoic as in the *** on the cycle stacking patterns,26 thirdorder sequences can be distinguished and these group into 6 second-order,transgressiveregressive megasequences(or sequence sets),all reflecting a composite,hierarchical succession of relative sea-level changes.

关键词： peritidal carbonate cycles Milankovitch rhythms Wumishan Formation Mesoproterozoic Tianjin North China

Facies-succession and architecture of the third-order sequences and their stratigraphic framework of the Devonian in Yunnan-Guizhou-Guangxi area,South China

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Journal of Palaeogeography 2013年第1期2卷 93-108页

作者： mei mingxiang Maurice E.Tucker School of Earth Science and Mineral Resources China University of Geosciences (Beijing) Department of Geological Sciences University of Durham

The Caledonian orogeny at the end of the Silurian resulted in great changes in the palaeogeography in the Yunnan-Guizhou-Guangxi area of South China; the continental area of the Early Paleozoic evolved into the extensive Dian-Qian-Gui Sea in the Late Paleo-zoic. Early in the Devonian, as a result of a major transgression, seawater encroached gradually from the south to the north and clastic facies were deposited. Carbonate deposition was then established in the Yunnan-Guizhou-Guangxi area, with a palaeogeography marked by attached platforms, isolated platforms and narrow basins. As a result of the Ziyun movement towards the end of the Devonian, the Upper Devonian strata are regressive and thin out from the open-sea to the land areas. A study of the nature and distribution of sedimentary facies in space and time recognises 13 third-order sequences in the Devonian strata in Yunnan-Guizhou-Guangxi area, and these form two second-order sequences. The strata of the Lower Devonian comprise 5 third-order sequences (SQ1 to SQ5 ), which are dominated by transgressive clastics. 4 third-order sequences (SQ6 to SQ9 ) in the Middle Devonian are characterized by alternations of transgressive clastics and highstand carbonates. In the Upper Devonian, carbonates constitute 4 third-order sequences (SQ10 to SQ13 ), which are generally marked by the transgressive limestones and highstand dolomites. On the basis of earlier biostratigraphic studies, sea-level changes represented by the third-order sequences with their different facies successions are explored, and the sequence stratigraphic framework is established. There-fore, the Devonian strata in the study area provide an example for further understanding of depositional trends within the sequence-stratigraphic framework.

关键词： sequence stratigraphy Devonian Yunnan-Guizhou-Guangxi area South China

From Basin Black Shales to Platform Carbonate Rocks:A Study on Sequence Stratigraphy for the Lower Cambrian of the Upper-Yangtze Region in South China

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Acta Geologica Sinica(English Edition) 2007年第5期81卷 739-755页

作者： mei mingxiang MA Yongsheng ZHANG Hai MENG Xiaoqing CHEN Yonghong State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 School of Earth Sciences and Resources China University of Geosciences Beijing 100083 Department of Oil-Fields China Petrochemical Corporation Beijing 100029

In the Upper-Yangtze region, especially in Guizhou Province and its adjacent areas, the Lower Cambrian is well developed and is marked by a succession from black shales of the basin facies to carbonate rocks of the platform facies. The drowning event of the platform occurring at the turn from Sinian to Cambrian resulted in a set of black shales, i.e. the Niutitang Formation, which makes up the bottom part of the Lower Cambrian. With the shoaling of the sedimentary environment, a set of carbonate rocks, i.e. the Qingxudong Formation, was formed in the top part of the Lower Cambrian. Thus, the Lower Cambrian in the study area makes up one second-order sequence that can be further subdivided into five third-order sequences, and forms a regularly cyclic succession of transgression-regression. There is a regularly vertical stacking pattern for the third-order sequences in the second-order sequence. From bottom to top, the succession of the ＂CS （condensed section）＋HST （high-stand system tract）＂ of the third-order sequences is changed into the succession of the ＂TST （transgressive system tract）＋CS＋HST＂. Correspondingly, the drowning-type sequence boundary is changed into the exposure-type one. Therefore, both the second-order and the third-order sequences have similar sedimentary-facies architectures. A concomitant with these temporal changes, the Lower Cambrian with a thickness of 1000 m that contains five third-order sequences is changed into a condensed succession that cannot identify third-order sequences toward the southeast with the deepening of the sedimentary environment. According to the elementary features of the third-order sequences, i.e. the regularity o sedimentary-facies successions in space and the synchronism of sedimentary-environment changes in time, the detailed division of the third-order sequences at main logged sections in different paleogeographical background becomes the basis to establish the sequence-stratigraphic framework that can demonstrate

关键词： sequence-stratigraphy Lower Cambrian Upper-Yangtze region South China