Genetic processes and environmental significance of Lower Devonian brachiopod shell concentrations in Longmenshan area, Sichuan, China

Li, Fengjie; Qu, Xuelin; Du, Lin; Dai, Tingyong; Li, Junwu; Yang, Chengjin

doi:10.1016/j.jseaes.2015.10.021

Cited by 11 publications

(6 citation statements)

References 20 publications

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“…This interface is the boundary between Emsian and Eifelian and belongs to the type-II sequence interface. 21 The condensed section is located on the 13th layer and is a black shale with only a small amount of thin shell tentaculite.…”

Section: Resultsmentioning

confidence: 99%

“…Under the interface is the pale yellow quartz sandstone with cross-bedding and parallel bedding development, which belongs to the proximal-source storm deposits, and above the interface is micritic limestone. This interface is the boundary between Emsian and Eifelian and belongs to the type-II sequence interface . The condensed section is located on the 13th layer and is a black shale with only a small amount of thin shell tentaculite.…”

Section: Resultsmentioning

confidence: 99%

“…16 The Lower Devonian is composed of ascending order siliciclastic, mixed siliciclastic-carbonate, and carbonate rocks, which formed in marine environments ranging from nearshore to the outer shelf. 16,17,19,20 According to the stratigraphic division criteria of the Devonian in the northwestern of Sichuan Basin, 7,16,17,21 The Lower Devonian consists of Pingyipu Formation, Bailiuping Formation, Ganxi Formation, Xiejiawan Formation, and Ertaizi Formation, while the Middle Devonian consists of Yangmaba Formation, Jinbaoshi Formation, and Guanwushan Formation (Figure 2). The target layer Yangmaba Formation is in conformable contact with the Lower Devonian Ertaizi Formation.…”

Section: Geological Settingmentioning

confidence: 99%

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Analysis of Hybrid Facies, Hybrid Sequence, and Its Controlling Factors of the Devonian Yangmaba Formation in the Northwestern Sichuan Basin, Southern China

李凤杰

Yuan

Lin³

2021

ACS Omega

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Abundant hybrid sediments composed of clastic rocks and carbonate rocks were deposited in the Devonian Yangmaba Formation in the northwestern of Sichuan Basin. Based on the measurement of the Ganxi section in detail, combined with the observation of the 30 slices, the hybrid facies, and hybrid sequence, the hybrid deposit mechanism and its controlling factors of the Yangmaba Formation were analyzed. It shows that the hybrid facies consists of the hybrid shore at the lower and clastic hybrid shelf and carbonate hybrid shelf deposits at the middle-upper of the Yangmaba Formation. The hybrid sequence, which can be divided into four sedimentary system tracts: the shelf-margin systems tract (SMST), the transgressive system tract (TST), the early highstand systems tract (EHST), and the late highstand systems tract (LHST), was developed in the Yangmaba Formation. There are three hybrid mechanisms including punctuated mixing, facies mixing, and in situ mixing, and the first two are the main types in the Yangmaba Formation. The punctuated mixing and in situ mixing are the main hybrid mechanisms of hybrid shore and clastic hybrid shelf deposits, and the facies mixing is the main hybrid mechanism of clastic hybrid shelf and carbonate hybrid shelf deposits. The hybrid mechanisms are different among the system tracts: the punctuated mixing is the main mixing manner in the SMST and LHST and the facies mixing developed in the TST and EHST. Storm action is the most important controlling factor of punctuated mixing of the Yangmaba Formation. Relative sea level change, carbonate productivity or the rate of terrestrial clastic supply, and climate change are factors that control and affect hybrid deposits. SMST and HST are mainly related to changes in the relative sea level, while TST is controlled by sedimentary source recharge, and climate change affects the hybrid action of system tracts to varying degrees.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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Analysis of Hybrid Facies, Hybrid Sequence, and Its Controlling Factors of the Devonian Yangmaba Formation in the Northwestern Sichuan Basin, Southern China

李凤杰

Yuan

Lin³

2021

ACS Omega

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“…The cyrtomatodont hinge of G. vitreus with interlocked teeth and sockets increases the potential for the preservation of articulated shells relative to the non‐interlocking (deltidiodont) hinge of other brachiopods (Brett & Bordeaux 1991; Li et al . 2016). However, first, this interlocking effect is not sufficient to prevent disarticulation of brachiopod shells in DAs on present‐day, mainly temperate shelves.…”

Section: Discussionmentioning

confidence: 99%

How long does a brachiopod shell last on a seafloor? Modern mid‐bathyal environments as taphonomic analogues of continental shelves prior to the Mesozoic Marine Revolution

et al. 2022

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Carbonate skeletal remains are altered and disintegrate at yearly to decadal scales in present-day shallowmarine environments with intense bioerosion and dissolution. Present-day brachiopod death assemblages are invariably characterized by poor preservation on continental shelves, and abundant articulated shells of brachiopods with complete brachidia are thus not expected to be preserved if not rapidly buried. However, such preservation is paradoxically observed in shallow-water Palaeozoic and Mesozoic brachiopod assemblages. Here, we show that a bathyal death assemblage time-averaged to several millennia (Adriatic Sea) consists of sediment-filled articulated shells of Gryphus vitreus with complete brachidia. Post-mortem age distributions indicate that disintegration half-lives exceed several centuries (c. 500-1700 years). The high frequency of articulated but centuries-old shells (>50%) and the fitting of taphonomic models to post-mortem ages indicate that disarticulation half-life is unusually long (c. 200 years). Rapid sediment filling of shells: (1) inhibited disarticulation, loop fragmentation and colonization by coelobites; and (2) induced precipitation of ferromanganese oxides at redox fronts within shells. Sediment-filled articulated shells, however, still resided at the sediment-water interface as indicated by encrusters and sponges that infested them after death. Sediment-filled shells disintegrated through bioerosion and physical wear when residence in the taphonomically active zone exceeded c. 2000 years. We suggest that the articulation paradox is driven by the Mesozoic Marine Revolution (MMR) that escalated predation, bioturbation and organic matter recycling, all intensifying shell disintegration. A scenario with slow disarticulation in bathyal environments may have lead to preservation of articulated shells in shallow-water assemblages prior to the MMR.

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“…Shell beds are influenced by biological (such as intrinsic gregarious behavior of organisms, opportunistic species explosion), sedimentological (e.g., current rework, relative sea level changes, storm surges), and diagenetic controls (Kidwell, 1986; Kidwell and Holland, 1991; Li and Droser, 1997, 1999). The characteristics of the acrotretoid shell beds, including dense packing, parallel orientation to bedding, and low to moderate fragmentation, suggest that these shell concentrations may be interpreted as the products of storms (Fürsich and Oschmann, 1993; Fürsich and Pandey, 1999; Li et al, 2016; Samira et al, 2018). The large proportion of complete shells, in conjunction with a large range in shell size, likely reflects minimal transport and little hydraulic sorting.…”

Section: Discussionmentioning

confidence: 99%

First report of acrotretoid brachiopod shell beds in the lower Cambrian (Stage 4) Guanshan Biota of eastern Yunnan, South China

et al. 2020

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Brachiopod shell accumulations are abundant and diverse in the lower Cambrian strata of Yunnan Province, South China, but most commonly they are composed of linguloid and acrotheloid brachiopods. Here, we describe the first record of shell beds with high-density accumulations of microscopic acrotretoid brachiopods (usually <2 mm in width) in the muddy deposits of the Wulongqing Formation (Guanshan Biota, Cambrian Stage 4) in the Wuding area of Yunnan Province. The acrotretoid shell beds from the Wulongqing Formation vary from thin mm-thick pavements to more well-developed beds, several centimeters thick. The occurrence of remarkably rich acrotretoid shell beds indicates that microscopic lingulates began to exert an important role in hardening and paving the soft-substrate seafloor during the early Cambrian evolution of Phanerozoic “mixgrounds.” The new Guanshan material is referred to a new species, Linnarssonia sapushanensis n. sp., which differs from other species of Linnarssonia mainly in having a well-developed internal pedicle tube, as well as a relatively longer dorsal median septum. The occurrence of Linnarssonia sapushanensis n. sp. in the Wulongqing Formation in eastern Yunnan extend the oldest record of the genus on the Yangtze Platform of South China back to at least Cambrian Stage 4. UUID: http://zoobank.org/3e0c3878-6ce2-4eed-87bf-e39647c310c4

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Genetic processes and environmental significance of Lower Devonian brachiopod shell concentrations in Longmenshan area, Sichuan, China

Cited by 11 publications

References 20 publications

Analysis of Hybrid Facies, Hybrid Sequence, and Its Controlling Factors of the Devonian Yangmaba Formation in the Northwestern Sichuan Basin, Southern China

Analysis of Hybrid Facies, Hybrid Sequence, and Its Controlling Factors of the Devonian Yangmaba Formation in the Northwestern Sichuan Basin, Southern China

How long does a brachiopod shell last on a seafloor? Modern mid‐bathyal environments as taphonomic analogues of continental shelves prior to the Mesozoic Marine Revolution

First report of acrotretoid brachiopod shell beds in the lower Cambrian (Stage 4) Guanshan Biota of eastern Yunnan, South China

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