...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Sedimentology: Journal of the International Association of Sedimentologists >Sedimentary environments and depositional characteristics of the Middle to Upper Eocene whale-bearing succession in the Fayum Depression, Egypt
【24h】

Sedimentary environments and depositional characteristics of the Middle to Upper Eocene whale-bearing succession in the Fayum Depression, Egypt

机译：埃及法尤姆洼地中新世至上始新世鲸类演替的沉积环境和沉积特征

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The discovery of whale fossils from Eocene strata in the Fayum Depression has provoked interest in the life and lifestyle of early whales. Excellent outcrop exposure also affords the dataset to develop sedimentological and stratigraphic models within the Eocene strata. Previous work generally asserts that the thick, sand-rich deposits of the Fayum Depression represent shoreface and barrier island successions with fine-grained lagoonal and fluvial associations capping progradational successions. However, a complete absence of wave-generated sedimentary structures, a preponderance of thoroughly bioturbated strata and increasingly proximal sedimentary successions upwards are contrary to accepted models of the local sedimentological and stratigraphic development. This study considers data collected from two Middle to Upper Eocene successions exposed in outcrop in the Wadi El-Hitan and Qasr El-Sagha areas of the Fayum Depression to determine the depositional affinities of Fayum strata. Based on sedimentological and ichnological data, five facies associations (Facies Association 1 to Facies Association 5) are identified. The biological and sedimentological characteristics of the reported facies associations indicate that the whale-bearing sandstones (Facies Association 1) record distal positions in a large, open, quiescent marine bay that is abruptly succeeded by a bay-margin environment (Facies Association 2). Upwards, marginal-marine lagoonal and shallow-bay parasequences (Facies Association 3) are overlain by thick deltaic distributary channel deposits (Facies Association 4). The capping unit (Facies Association 5) represents a transgressive estuarine depositional environment. The general stratigraphic evolution resulted from a regional, tectonically controlled second-order cycle, associated with northward regression of the Tethys. Subordinate cycles (i.e. third-order and fourth-order cycles) are evidenced by several Glossifungites-ichnofacies demarcated discontinuities, which were emplaced at the base of flooding surfaces. The proposed depositional models recognize the importance of identifying and linking ichnological data with physical-sedimentological observations. As such - with the exception of wave-generated ravinement surfaces - earlier assertions of wave-dominated sedimentation can be discarded. Moreover, this study provides important data for the recognition of (rarely reported) completely bioturbated sand-dominated offshore to nearshore sediments (Facies Association 1) and affords excellent characterization of bioturbated inclined heterolithic stratification of deltaic deposits. Another outcome of the study is the recognition that the whales of the Fayum Depression are restricted to the highstand systems tracts, and lived under conditions of low depositional energy, low to moderate sedimentation rates, and (not surprisingly) in fully marine waters characterized by a high biomass.
机译：在Fayum凹陷的始新世地层发现鲸鱼化石，引起了人们对早期鲸鱼生活和生活方式的兴趣。出色的露头暴露也为始新世地层内的沉积学和地层学模型提供了数据集。先前的工作通常断言，法尤姆De陷的厚厚，富含沙子的沉积物代表了海岸面和屏障岛的演替，并伴有细化的泻湖和河流相伴，限制了演替演替。然而，完全没有波浪产生的沉积结构，大量的完全生物扰动的地层和越来越近的向上的沉积演替，与当地沉积学和地层发育的公认模型相反。这项研究考虑了从Fayum凹陷的Wadi El-Hitan和Qasr El-Sagha露头露头暴露的两次中新世至上新世接替序列收集的数据，以确定Fayum地层的沉积亲和力。根据沉积学和鱼类学数据，确定了五个相协会（相协会1到相协会5）。据报道的相协会的生物学和沉积学特征表明，鲸鱼砂岩（相协会1）在一个宽阔，开放，静止的海洋海湾中记录了远端位置，该海湾突然被海湾边缘环境所继承（相协会2）。向上，边缘海洋泻湖和浅湾副流（相系3）被厚厚的三角洲分布河道沉积物所覆盖（相系4）。封盖单元（Facies Association 5）代表海侵海床沉积环境。总体地层演化是由区域构造控制的二阶旋回引起的，与特提斯的北移有关。下界（即三阶和四阶循环）由几个划定为不连续面的光泽-辉石岩相证明，它们位于水淹面的底部。所提出的沉积模型认识到了识别鱼类学数据并将其与物理沉积学观测联系起来的重要性。因此，除了波浪产生的沟壑表面以外，可以忽略波浪主导的沉积的早期断言。此外，这项研究为识别（很少报道）完全生物扰动的以砂为主的近海至近岸沉积物提供了重要数据（Facies Association 1），并为三角洲沉积物的生物扰动斜异质分层提供了出色的特征。该研究的另一项成果是认识到，法尤姆凹陷的鲸鱼被限制在高位系统域，并且生活在低沉积能，低至中等沉积率的条件下，并且（毫无意外地）生活在特征为全海域的海水中。高生物量。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号