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Structural geometry of the Jura-Cretaceous rift of the Middle Magdalena Valley basin, Colombia.

机译：哥伦比亚马格达莱纳山谷中部侏罗-白垩纪裂谷的结构几何。

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摘要

The Middle Magdalena Valley (MMV) basin, Colombia, evolved to its actual configuration through several stages closely linked with the tectonic events of the northwest corner of South America.; Early Jurassic extensional deformation related to the break-up of Pangea, resulted in the development of rift structures in the MMV basin area. The syn-rift infill consists of fluvial and lacustrine sedimentary rocks (Jordan, Giron and Santos formations), overlain by limestones and shales (Basal Lime Group). Irregular discontinuous reflectors, rotated by normal faults and increasing thickness towards the south-east, characterize the Jurassic syn-rift section. In Early Aptian, a post-rift phase controlled by thermal subsidence started. During this phase the Simiti, La Luna and Umir formations were deposited. The seismic character of this sequence consists of continuous reflections and gradual changes in thickness. From the end of the Cretaceous through the present, the collision of oceanic terranes against the western margin of Colombia caused thrusting in the Central and Eastern Cordilleras. The MMV basin became an intermontane basin. Sedimentation during this period consisted of fluvial deposits accumulated as continental molasses.; I propose an asymmetrical half graben geometry for the Jura-Cretaceous structure of the northern part of the MMV basin. The range-bounding faults of the Eastern Cordillera: the Bucaramanga, La Salina, and Cambao-Bituima faults were originally normal faults that controlled thickness of the synrift sequence and, in general, the geometry of the structure.; The rift structures are well preserved in the study area. However, most of the preserved faults were inverted during the Tertiary orogeny. Inversion can be documented by structures such as shortcuts, thicker rift strata on the hanging wall, and by variation of fault throw.
机译：哥伦比亚中部马格达莱纳谷盆地（MMV）通过与南美西北角的构造事件密切相关的几个阶段演变成其实际构造。与Pangea破裂有关的侏罗纪早期伸展变形，导致了MMV流域地区裂谷构造的发展。同裂谷填充物由河流相和湖相沉积岩（乔丹，吉伦和桑托斯地层）组成，上面覆盖着石灰岩和页岩（基础石灰岩群）。侏罗纪同裂谷段是不规则的不连续反射体，由正常断层旋转并向东南方向增加厚度。在Apty早期，受热沉降控制的裂谷后阶段开始了。在此阶段，沉积了Simiti，La Luna和Umir地层。该序列的地震特征包括连续的反射和厚度的逐渐变化。从白垩纪末期到现在，海洋地层与哥伦比亚西部边缘的碰撞在中部和东部山脉造成了冲动。 MMV盆地成为山间盆地。在此期间，沉积物由堆积为大陆糖蜜的河流沉积物组成。我为MMV盆地北部的侏罗-白垩纪构造提出了一种不对称的半grab陷几何形状。东部山脉的山脉边界断层：布卡拉曼加，拉萨利纳和坎宝-伯图马断层最初是正常断层，控制着同理层的厚度，通常控制着构造的几何形状。研究区的裂谷构造保存完好。但是，在第三纪造山运动中，大多数保留的断层是倒置的。倒转可以通过诸如捷径，悬壁上较厚的裂谷层之类的结构以及断层变化的变化来证明。

著录项

  • 作者

    Rolon, Luisa F.;

  • 作者单位

    West Virginia University.;

  • 授予单位 West Virginia University.;
  • 学科 Geology.
  • 学位 M.S.
  • 年度 2004
  • 页码 69 p.
  • 总页数 69
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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