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Cenozoic seismic stratigraphy and structure of the continental margin offshore Vietnam, South China Sea.

机译：越南南海近海大陆边缘的新生代地震地层和构造。

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摘要

Time-structure maps of the basement in the study area show two different sets of faults. These faults trend NNW-SSE in the northern and middle areas and NE-SW in the southern area. Strain ellipse indicates that the fault patterns in the northern area may have been formed by a left-lateral movement. This left-lateral movement may be related to the southeastward extrusion and clockwise rotation of Sundaland during the collision of India and Asia. Faults in the southern area which trend NE-SW may have been initiated during the Paleocene sea-floor spreading in the Southwest subbasin. The faults may have been reactivated during the middle Miocene.; Cenozoic sediments offshore Vietnam, whose thicknesses range between 0.5 second and more than 4 seconds two-way travel-time, consist of syntectonic and posttectonic sequences. Syntectonic sediments overlie a pronounced rift-onset unconformity. Posttectonic sediments which overlie a breakup unconformity contain five sequences whose ages are inferred to be the upper Oligocene-lower Miocene, lower Miocene-middle Miocene, middle Miocene-upper Miocene, Pliocene and Pleistocene-Recent. Maximum rates of posttectonic sedimentation generally increase throughout the time. The highest increase in sedimentation rates occurred during the Pleistocene-Recent in the middle area. The increase rates of sediment supply may have been related to the widespread volcanism in Indochina during the Pliocene-Recent and to the slight increase in basin subsidence.; Thirteen seismic facies within posttectonic sequences were recognized and mapped. These facies indicate shelfal deposits, deltaic sediments, turbidite sediments, channel fill deposits, upper fan deposits, and shale diapirs. Shelfal sediments are commonly found in each sequence. Upper fan deposition occurred in the middle area during the upper Oligocene-lower Miocene. Deltaic sediments are found in the lower Miocene-middle Miocene, middle-upper Miocene, and upper Pliocene-Holocene sequences. Shelf-edge progradation and upper slope slumping, which have occurred since the early Miocene, were intensive during the upper Pliocene-Holocene.
机译：研究区域地下室的时间结构图显示了两组不同的断层。这些断层在北部和中部地区趋于NNW-SSE，在南部地区趋向NE-SW。应变椭圆表示北部地区的断层样式可能是由左旋运动形成的。这种左旋运动可能与印度和亚洲相撞期间圣达兰的向东南挤压和顺时针旋转有关。在西南部盆地的古新世海底扩散期间，可能已向南部断层发展了NE-SW趋势。断层可能在中新世中期已被重新激活。越南近海新生代沉积物的厚度范围在0.5秒至4秒之间（双向传播时间），由构造和后构造序列组成。构造沉积物覆盖着明显的裂谷不整合面。构造破裂不整合面之上的构造后沉积物包含五个序列，其年龄被推断为上中新世-下中新世，下中新世-中中新世，中中新世-上中新世，上新世和上新世。构造后沉积的最大速率通常随时间增加。沉积速率的最大增加发生在中部地区的更新世时期。沉积物供应量的增加可能与上新世以来印度支那的广泛火山活动以及盆地沉降的轻微增加有关。识别并绘制了大地构造序列内的13个地震相。这些相表明了陆架沉积物，三角洲沉积物，浊质沉积物，河道填充物沉积物，上部扇状沉积物和页岩底物。陆架沉积物通常出现在每个序列中。在上渐新世-下中新世期间，上部扇形沉积发生在中部地区。在下中新世-中新世，中上中新世和上新世-全新世序列中发现了三角洲沉积物。自中新世早期以来发生的陆缘隆升和上斜坡塌陷，在上新世-全新世期间是密集的。

著录项

  • 作者

    Wirasantosa, Sugiarta.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Geology.; Geophysics.; Geotechnology.
  • 学位 Ph.D.
  • 年度 1992
  • 页码 239 p.
  • 总页数 239
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;地球物理学;地质学;
  • 关键词

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