Paleoecology and Taphonomy of an Edrioasteroid-Dominated Hardground Association from Tentaculitid Limestones in the Early Devonian of New York: A Paleozoic Rocky Peritidal Community
Paleoecology and Taphonomy of an Edrioasteroid-Dominated Hardground Association from Tentaculitid Limestones in the Early Devonian of New York: A Paleozoic Rocky Peritidal Community
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DOI：
10.1669/0883-1351(2003)018
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发表时间：
2003-06
期刊：
影响因子：
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通讯作者：
Sean R. Cornell;C. Brett;C. Sumrall
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文献类型：
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作者：
Sean R. Cornell;C. Brett;C. Sumrall
摘要纽约州中东部曼利乌斯组下泥盆统（Lochkovian）Thacher石灰岩段中一个罕见的潮缘硬地的埋藏学、沉积学和古生态学研究为沉积动力学和古代硬基质栖息生物的生活方式提供了深入的见解。硬地面出现在一个浅向上碳酸盐循环的顶部附近，略低于干燥开裂泥晶带石灰岩。坚硬表面发育在部分挖出的触手石铺路石上，上覆粒状钙质粉砂岩;坚硬地面的起伏约为2-3 cm，上覆一层薄的硅质粘土泥层。硬地在垂直于沉积走向的横向距离约35公里的初步相关性表明，该地区的地形轮廓非常柔和，并发展了广泛的潮缘硬地路面。Tentaculites gyracanthus发生在一个密集的路面强烈双峰排列的外壳与ENE到WSW方向，平行于推断的古海岸线。有些标本也发生垂直嵌入，这表明可能的生活在坚实的基板取向。这些贝壳孔周围的坑的存在表明，周围的贝壳挖入基底的冲刷效果。不规则硬地表面的上部优先殖民地由一个未描述的小postibulinid edrioasteroid，这可能有点像橡子藤壶生活在波扫岩石平台。后者的种群结构中，幼鱼很少。虽然动物群在Thacher石灰岩包括leperditian介形虫，枝和encrusting苔藓虫，Howellella vanuxemi腕足动物，和罕见的pterioid双壳类，硬地社区是相当有限的。这种低多样性组合代表了一种不寻常的edrioasteroid为主的硬地社区类型，坚持至少从早奥陶世到晚泥盆世在潮缘硬地和rockgrounds。
Abstract The taphonomy, sedimentology, and paleoecology of a rare peritidal hardground in the Lower Devonian (Lochkovian) Thacher Limestone Member of the Manlius Formation in east-central New York State provides insights into sediment dynamics and modes of life of ancient hard substrate-inhabiting organisms. The hardground occurs near the top of a shallowing-upward carbonate cycle, slightly below desiccation-cracked micritic ribbon limestones. The hard surface developed on a partially exhumed tentaculitid pavement and overlying pelletal calcisiltite; the hardground has a relief of about 2–3 cm and is overlain by a thin siliciclastic mud layer. Tentative correlation of the hardground across a lateral distance of about 35 km perpendicular to depositional strike suggests a very subdued topographic profile for this region and development of an extensive peritidal hardground pavement. Tentaculites gyracanthus occurs in a dense pavement of strongly bimodally aligned shells with an ENE to WSW orientation, parallel to the inferred paleoshoreline. Some specimens also occur vertically embedded, suggesting possible life orientations within firm substrates. The presence of pits around the apertures of these shells suggests scouring effects around the shells burrowed into the substrate. Upper portions of the irregular hardground surface were preferentially colonized by an undescribed small postibulinid edrioasteroid, which may have lived somewhat like acorn barnacles on wave-swept rock platforms. The latter shows a population structure with few juveniles. Although fauna within the Thacher limestone includes leperditian ostracodes, ramose and encrusting bryozoans, Howellella vanuxemi brachiopods, and rare pterioid bivalves, the hardground community is rather limited. This low-diversity assemblage represents an unusual edrioasteroid-dominated hardground community type that persisted from at least Early Ordovician to Late Devonian in peritidal hardgrounds and rockgrounds.