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DOI	10.1016/j.palaeo.2019.01.027
	Disorientation of corals in Late Ordovician lime mudstone: A case for ephemeral; biodegradable substrate?
	Lee M.; Elias R.J.; Choh S.-J.; Lee D.-J.
发表日期	2019
ISSN	0031-0182
起始页码	55
结束页码	65
卷号	520
英文摘要	Massive coralla representing the tabulate coral Agetolites occur on a lime mudstone bed in the Upper Ordovician Xiazhen Formation of southeastern China. Other fossils include solitary rugose corals, bryozoans, trilobites, and mollusks. In addition, abundant spicules and spicule networks suggest that sponges were widespread. The occurrence of intact, unabraded fossils in micritic matrix and the absence of high-energy sedimentary structures indicate deposition in low-energy conditions. Thin section analysis of disoriented specimens demonstrates that geopetal indicators are consistent with stratigraphic “up” and differ from the growth axes of the corals, implying that geopetal infillings formed after disorientation. The growth axes of coralla were not redirected during life, suggesting that the corals were either dead at the time of disorientation or died as a result of disorientation. An examination of cyclomorphism indicates that the corals died at different times, rather than during a single event. A close association between sponges and corals is suggested by the presence of spicule networks in calices and intracorallum spaces of Agetolites. It is hypothesized that disorientation of corals was related to growth on biodegradable substrates. We suggest that many coral larvae settled on sponges that formed “sponge meadows”. Disorientation of the resulting corals may have occurred when (1) a host sponge could no longer support the weight of a coral and collapsed, (2) increasing weight or imbalance of a coral caused it to fall off the sponge, or (3) a coral became detached when the sponge died and decomposed. If the coral was alive, sudden deposition in a disoriented position within muddy sediment resulted in its death. Disorientation of massive skeletons, such as colonial coralla, is most commonly attributed to water energy. This study suggests that ephemeral substrates may have been involved in some cases. © 2019 Elsevier B.V.
英文关键词	Geopetal structure; Palaeoecology; Sponges; Tabulate coral; Taphonomy
语种	英语
scopus关键词	biodegradation; biostratigraphy; bryozoan; coral; fossil record; mollusc; mudstone; Ordovician; paleoecology; skeleton; spicule; sponge; substrate; taphonomy; trilobite; ultrastructure; China; Anthozoa; Bryozoa; Mollusca; Trilobitomorpha
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151031
作者单位	Division of Polar Earth-System Sciences, Korea Polar Research Institute, Incheon, 21990, South Korea; Department of Geological Sciences, University of Manitoba, Winnipeg, R3T 2N2, Canada; Department of Earth and Environmental Sciences, Korea University, Seoul, 02841, South Korea; Department of Earth and Environmental Sciences, Andong National University, Andong, 36749, South Korea; College of Earth Sciences, Jilin University, Changchun, 130061, China
推荐引用方式 GB/T 7714	Lee M.,Elias R.J.,Choh S.-J.,et al. Disorientation of corals in Late Ordovician lime mudstone: A case for ephemeral; biodegradable substrate?[J],2019,520.
APA	Lee M.,Elias R.J.,Choh S.-J.,&Lee D.-J..(2019).Disorientation of corals in Late Ordovician lime mudstone: A case for ephemeral; biodegradable substrate?.Palaeogeography, Palaeoclimatology, Palaeoecology,520.
MLA	Lee M.,et al."Disorientation of corals in Late Ordovician lime mudstone: A case for ephemeral; biodegradable substrate?".Palaeogeography, Palaeoclimatology, Palaeoecology 520(2019).