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首页> 外文学位 >Depositional environments and burial history of the Late Early Pliocene, Moruga Group, south coast, Trinidad, West Indies (Trinidad and Tobago).
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Depositional environments and burial history of the Late Early Pliocene, Moruga Group, south coast, Trinidad, West Indies (Trinidad and Tobago).

机译：上新世晚期，莫鲁加群，南海岸，特立尼达，西印度群岛（特立尼达和多巴哥）的沉积环境和埋葬历史。

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摘要

The depositional style, biostratigraphy and burial history of the Late Early Pliocene, Moruga Group were studied in outcrop and the subsurface, along the south coast of Trinidad to determine its depositional environments, sediment sources, geologic age, and diagenetic history.; During Late Miocene to Early Pliocene time the northerly prograding, ancestral Orinoco delta transported large volumes of terrestrially derived subarkosic and sublitharenitic sand to the Northern Venezuela/Columbus Basin area. The influence of sea level, coupled with tectonics provided a depocenter which adjusted to accommodate more than 1600 meters of Late Early Pliocene sandstones, siltstone and mudstones of the Moruga Group.; The Moruga Group was deposited by gravity flows and turbidity currents which were very effective in resedimenting the originally deltaic sediments. Three distinct facies were identified on the basis of sandstone/mudstone ratio, sedimentary structures and bedding characteristics. The facies associations, together with the widespread occurrence of complete and truncated Bouma cycles, indicate deposition in a delta-fed submarine ramp environment, by high efficiency, turbidity currents and gravity flows. This system lacked some elements (e.g. canyons) of classic turbidity current models. The Moruga Group was deposited as viscous sheet gravity flows, (turbidites) which were mobilized downslope from a line source as unstable sediments piled up on the prograding delta slope.; Petrography and heavy mineral analyses indicate that the sediments were derived from a mixed igneous and metamorphic source and were the result of rapid erosion and transportation from the Andes and Guyana Shield areas.; The burial diagenetic history of the Moruga Group was evaluated using data from clay mineralogy, organic and inorganic geochemistry. A typical Gulf Coast type clay mineral assemblage was recognized. Evidence suggest that source and depositional environment might have been the major control on the diagenetic mineral association encountered. Rock Eval Pyrolysis indicate that very large amounts of the organic geochemical components are reworked, and cannot be used in source rock evaluation of these sediments. Where rock eval pyrolysis was possible the sediments were determined to be gas prone but immature. Stable isotope data suggest no relationship between carbon and oxygen isotopic compositions, indicating a complex diagenetic history. (Abstract shortened with permission of author.)
机译：；在特立尼达南部沿海的露头和地下，研究了上新世晚期，Moruga群的沉积方式，生物地层学和埋藏历史，以确定其沉积环境，沉积物来源，地质年龄和成岩史。在中新世晚期至上新世早期，北进阶祖先的奥里诺科三角洲将大量陆生的亚深水和亚砾质砂砾岩运到委内瑞拉北部/哥伦布盆地地区。海平面的影响加上构造学使沉积中心得以调整，以适应莫鲁加群的1600多米的早新世晚期砂岩，粉砂岩和泥岩。莫鲁加群是由重力流和浑浊流沉积的，这对重新沉积最初的三角洲沉积物非常有效。根据砂岩/泥岩比，沉积构造和层理特征，确定了三个不同的相。这些相的结合以及完整的和截断的布马循环的普遍发生，表明通过高效，浊流和重力流在三角洲馈送的海底斜坡环境中沉积。该系统缺少经典浊度模型的某些要素（例如峡谷）。 Moruga群沉积为粘性片状重力流（浊石），由于不稳定的沉积物堆积在三角洲斜坡上而从线源下坡移动。岩相学和重矿物分析表明，沉积物来自火成岩和变质岩混合源，是安第斯山脉和圭亚那盾构地区快速侵蚀和运输的结果。使用粘土矿物学，有机和无机地球化学数据评估了Moruga集团的埋葬成岩历史。公认的是典型的墨西哥湾沿岸型粘土矿物组合。有证据表明，来源和沉积环境可能是遇到的成岩矿物协会的主要控制因素。岩石评估热解表明，大量的有机地球化学成分已被重制，不能用于这些沉积物的源岩评估中。在可能进行岩石热解的情况下，沉积物被确定为易燃气体但未成熟。稳定的同位素数据表明，碳和氧同位素组成之间没有关系，表明复杂的成岩史。 （摘要经作者许可缩短。）

著录项

  • 作者

    Harry, Brian E.;

  • 作者单位

    University of Cincinnati.;

  • 授予单位 University of Cincinnati.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 1992
  • 页码 345 p.
  • 总页数 345
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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