• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Facies >An upper Paleogene shallowing-upward sequence in the southern Sandino Forearc Basin (NW Costa Rica): response to tectonic uplift
【24h】

An upper Paleogene shallowing-upward sequence in the southern Sandino Forearc Basin (NW Costa Rica): response to tectonic uplift

机译：南部桑迪诺前臂盆地（西北哥斯达黎加）上古近纪上-浅层向上序列：对构造隆升的响应

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 Sandino Forearc Basin of western Nicaragua and northwestern Costa Rica (Central America) provides a Campanian to Pliocene sedimentary record. The study of the onshore part of the basin in northwestern Costa Rica reveals for the first time the occurrence of upper Paleogene shallow-marine siliciclastic and carbonate sequences. These sequences have remained undescribed so far and are grouped herein into two new lithostratigraphic units-the upper Eocene Junquillal Formation (Fm.) and the upper Oligocene Juanilla Fm. The upper Eocene Junquillal Fm. is characterized by storm-related, arenitic to conglomeratic deposits comprised in metric, massive amalgamated beds. The shallow shelfal environment of deposition is attested by the presence of hummocky and swaley cross-stratifications. The lithologies of the Junquillal Fm. were previously considered to be part of the underlying, deep-water turbiditic deposits of the Eocene Descartes Fm. The deposition of the Junquillal Fm. is indicative of tectonic uplift that forced regression, which affected the southeastern part of the Sandino Forearc Basin during the late Eocene. The upper Oligocene Juanilla Fm. unconformably overlies the Junquillal Fm. and occurs as a 25-m-thick, 700-m-wide outcrop on Isla Juanilla. It is composed essentially of nodular, coral framestones exhibiting massive, closely packed corals in growth position that are associated with coralline red algae and Larger Benthic Foraminifera (LBF). A late Oligocene age of the reef is attested by LBF assemblages occurring in two different facies. The Juanilla Fm. coral reef is a unique exposure, characterized by extensive constructed coral framework, and which has no equivalent in the Oligocene geological record of Central America. The reef grew on a short-lived, siliciclastic-poor tectonic high, which developed in relation to a lower Oligocene, basin-scale folding event in the Sandino Forearc Basin.
机译：尼加拉瓜西部和哥斯达黎加西北部（中美洲）的桑迪诺前臂盆地提供了坎潘期至上新世的沉积记录。对哥斯达黎加西北部盆地陆上部分的研究首次揭示了上古近纪浅海硅质碎屑岩和碳酸盐岩层序的发生。到目前为止，这些序列尚未描述，在此分为两个新的岩石地层学单元-始新世准qui尔地层（Fm。）和渐新世胡安尼拉Fm。始新世Junquillal Fm。其特征是与暴风雨有关的，从暴风雨到大型砾石混合床中的砾岩沉积物。浅层架状沉积环境通过存在山丘状和swaley交叉分层来证明。 Junquillal Fm的岩性。以前被认为是始新世笛卡尔盆地深层浊流沉积的一部分。 Junquillal Fm的沉积。表明始新世末期构造隆升强迫回归，影响了桑迪诺前臂盆地的东南部。上渐新世胡安尼拉Fm。不合格地覆盖了Junquillal Fm。并以25米厚，700米宽的露头出现在胡安尼拉岛上。它基本上由结节状的珊瑚框架石组成，在生长位置上呈现出大量紧密堆积的珊瑚，这些珊瑚与珊瑚红藻和较大的底栖有孔虫（LBF）有关。礁的渐新世晚期可以通过在两个不同相中发生的LBF组合来证明。 Juanilla Fm。珊瑚礁是一个独特的地方，其特征是构造广泛的珊瑚框架，在中美洲的渐新世地质记录中没有类似的发现。珊瑚礁生长于一个短暂的，硅质碎屑较差的构造高点上，该构造高点是与桑迪诺前臂盆地中渐新世较低的盆地规模的褶皱事件有关的。

著录项

相似文献

  • 外文文献
  • 中文文献
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