Neoproterozoic Molar-tooth Structure and Constraint of Depositional Facies and Environment in the North China Platform in Jiangsu, Anhui and Liaoning, Eastern China

Liu, Yongqing; Gao, Lei; Liu, Yanxue

doi:10.1111/j.1755-6724.2005.tb00919.x

Cited by 10 publications

(2 citation statements)

References 18 publications

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“…nonfossils, or sedimentary structures, and even microbialinduced sedimentary structures (Hofmann. 1971 ;Walter et al, 1990; Fedokin and Runnegar, 1992; Schieber, 1999; Noffke et al, 2001; Parizot et al, 2005; Liu et al, 2005;Mei et al, 2006). Although Dickinsonia Sprigg and Sprigginu Glaessner from the Ediacara fauna in South Australia were interpreted us annelids because of their metameres (e.g.. Glaessner, 1984; Jenkins, 1992 Doushantuo Formation.…”

Section: Introductionmentioning

confidence: 99%

Annelid from the Neoproterozoic Doushantuo Formation in Northeastern Guizhou, China

Wang

2008

Acta Geologica Sinica (Eng)

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Wenghuiia jiangkouensis gen. et sp. nov., characterized by modern annelid taxonomy in morphology and functional biology, is found in black carbonaceous shale from the Neoproterozoic Ediacaran Doushantuo Formation (about 555 Ma) near Wenghui, Jiangkou, northeastern Guizhou Province. The elongate, cylindrical body is composed of many homologous metameres with a true coelom and coelomic pouches. The mouth is at the front of the first segment and the anus at the end of body. A long 11th or 12th segment is probably functionally for procreation, being a clitellum. There are parapodia on the venter of the segments from the rear of the second segment to the front of the clitellum. The setae on all metameres, on the parapodia, and around the anus, differ. In the centre of body, a line probably represents the alimentary canal passing through the body from mouth to anus. A closed vascular system consists of a dorsal vessel at least. W. jiankouensis might represent the oldest discovered ‘modern’ annelid but it is not a primitive type. It lived on the depositional surface of a shallow sea with an environment of calm‐water and abundant light.

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Section: Introductionmentioning

confidence: 99%

Annelid from the Neoproterozoic Doushantuo Formation in Northeastern Guizhou, China

Wang

2008

Acta Geologica Sinica (Eng)

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“…The characteristics of sedimentation and relations to reservoirs have been studied (Serra, 1986;Jiang, 1995;Cross and Lessenger, 1996;Zhang et al, 2002;Xia et al, 2004;Xin et al, 2004;Zhang et al, 2004;B o n g et al, 2004;Wan et al, 2005;Sun et al, 2006;Zhang and Deng, 2006;. According to the sedimentary facies division scheme and standard accepted by most people at present (Wang and Zhang, 1996;Yu et al, 2002;Liu et al,2005), we have recognized two types of sedimentary facies: the lake facies and the delta facies, and seven sedimentary micro-facies by synthetically analyzing the facies characteristics of the rock type, color, bedding structure, sedimentary structure, biology and the characteristics of the logging curve of the third member of the Qingshankou Formation, which appeared in the wells drilled in the investigated area. And, on the above bases, the space overlay relation of different types of sedimentary microfacies of the third member of Qingshankou is analyzed by a unified division of the sedimentary micro-facies of each well, then the macro heterogeneity of reservoir beds of the Qingshankou Formation is discussed in combination with the characteristics of sand body permeability.…”

Section: Introductionmentioning

confidence: 99%

Sedimentary Micro‐facies and Macro Heterogeneity of Reservoir Beds in the Third Member of the Qingshankou Formation, Qian'an Area, Songliao Basin

Shan

Jinxiang

Sachsenhofer

et al. 2007

Acta Geologica Sinica (Eng)

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An analysis of drill cores and well logs shows that the main micro-facies of the third member sand bodies of the Qingshankou Formation in Qian'an are subaqueous distributary channel facies, sheet sand facies and subaqueous fan facies (olistostrome). Maps showing the distribution of these micro-facies together with inter-channel bay and prodelta mocro-facies are presented for different time-slices (lower, middle and upper parts of the Qingshankou Formation). These maps reveal the instability and change of sediment transport in the Baokang sedimentary system during the depositional period. Sediment transport was from the west in the early stage, from the south in the middle stage and from the northwest in the late stage. Values of thickness, porosity and permeability of the sand bodies in the third member of the Qingshankou Formation show that they have low to medium porosity and low permeability, and are characterized by serious reservoir heterogeneity. The joints between micro-facies and subaqueous fan micro-facies are characterized by the highest heterogeneity, the sheet sand and distal sand bar subfacies come next, and the heterogeneity of the subaqueous distributary channel sand bodies is relatively weak.

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Sand veins and MISS from the Mesoproterozoic black shale (ca. 1.7 Ga) in North China: Implication for methane degassing from microbial mats

Shi

Jiang

Chuan-heng

et al. 2008

Sci. China Ser. D-Earth Sci.

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The Mesoproterozoic Chuanlinggou Formation (ca. 1.7 Ga) consists mainly of dark-gray to black shales that are widespread in the North China Platform. Abundant centimeter-scale sand veins are present within the shale layers of this unit, particularly in the middle part. Sand veins display ptygmatic shapes, perpendicular or with a high angle to bedding planes. They penetrate the black shale layers but are often terminated by thin, lenticular sandstone beds, forming small-scale 'tepee-like' structures. On bedding planes, sand veins are expressed as small ridges with 1-3 mm positive relief. Lack of polygonal shapes and their occurrence in thinly laminated, relatively deep-water shales preclude an origin from sand-filled desiccation cracks. Instead, their close association with microbially induced sedimentary structures (MISS) such as micro-wrinkles and gas blisters, putative bacterial fossils (possibly coccoidal cyanobacteria) and framboidal pyrites, suggests that they were formed by degassing of methane from microbial mat decay. Methane gas disrupted overlying sedimentary layers, creating fractures open to seawater. Fine-grained quartz sands, which were transported into the depositional environment by strong winds, filled the fractures. Sand-filled fractures were shortened and folded during burial compaction, forming ptygmatic shapes. The presence of dispersed dolomite and siderite in these sand veins suggests authigenic carbonate precipitation from anaerobic oxidation of methane (AOM). Sand veins are intensely distributed within the Chuanlinggou Formation and are spatially widespread in the North China Platform. If their methane origin is confirmed, they may have important implications for the Mesoproterozoic paleoclimate. With anoxic oceans and low seawater sulfate concentration during the Mesoproterozoic, methane release from microbial mat decay and/or microbial methanogenesis during shallow burial may have been proportionally higher than that of the modern marine environments, with resultant increase in the relative importance of methane in maintaining the Mesoproterozoic greenhouse climate. sand veins, methane degassing, microbial mats, Chuanlinggou Formation, Mesoproterozoic, North China Platform During most of the Proterozoic (from ca. 2.4 to 0.78 Ga), the Earth was ice-free, with surface temperature probably around 40-55℃ [1,2] , constituting a rare long-lasting warm period in the earth history [3,4] . Given the fact that the solar luminosity was about 15%-25% lower than today [3,5] , an ice-free, warm Proterozoic Earth surface would require an atmospheric methane concentration at least of 100-300 ppmv [6] . Due to the short resident time of methane in atmosphere, maintaining a

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Neoproterozoic Molar-tooth Structure and Constraint of Depositional Facies and Environment in the North China Platform in Jiangsu, Anhui and Liaoning, Eastern China

Cited by 10 publications

References 18 publications

Annelid from the Neoproterozoic Doushantuo Formation in Northeastern Guizhou, China

Annelid from the Neoproterozoic Doushantuo Formation in Northeastern Guizhou, China

Sedimentary Micro‐facies and Macro Heterogeneity of Reservoir Beds in the Third Member of the Qingshankou Formation, Qian'an Area, Songliao Basin

Sand veins and MISS from the Mesoproterozoic black shale (ca. 1.7 Ga) in North China: Implication for methane degassing from microbial mats

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