Mud volcanoes at the shelf margin of the East China Sea
Mud volcanoes at the shelf margin of the East China Sea
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DOI：
10.1016/s0025-3227(02)00678-3
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发表时间：
2003-03
期刊：
影响因子：
2.9
通讯作者：
P. Yin;S. Berné;P. Vagner;B. Loubrieu;Zhenxia Liu
中科院分区：
文献类型：
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作者：
P. Yin;S. Berné;P. Vagner;B. Loubrieu;Zhenxia Liu
在东中国海的陆架边缘首次绘制了直径从几十米到几百米，高度从几米到40米的大致圆形的沉淀丘。高分辨率地震剖面以及条带测深和声学数据表明，这些特征在ECS外陆架和冲绳海槽上西坡上是常见的。它们与异常大的麻点有关，深达40米，直径600米。在地震记录上，亮点、相位反转和其他声学异常表明，气体和/或流体的逃逸在这些丘陵的形成中发挥了重要作用。它们通常与沿冲绳海槽西坡发生的正常断层有关，这些断层充当流体迁移的管道。在区域地层对比的基础上，提出泥浆和流体的物源深度大于235ka。渗流过程被怀疑是非常近期的，而且可能仍然活跃，这是基于以下事实：(1)尽管沉积速率很高，但土丘没有被现代沉积物埋藏，以及(2)最后一次冰川最大沉积在土丘就位时被改造。碳酸盐胶结沉积和可能与流体渗漏有关的深水生物礁可能是当地极高后向散射声波相斑块的起源，用带状测深系统绘制了地图。
Roughly circular sediment mounds, varying from tens to hundreds of meters in diameter and from a few meters up to 40 m in height, have been mapped for the first time at the shelf edge of the East China Sea (ECS). High-resolution seismic profiles, together with swath bathymetric and acoustic data, indicate that these features are common on the ECS outer shelf and on the upper western slope of the Okinawa Trough. They are associated with unusually large pockmarks, up to 40 m in depth and 600 m in diameter. On seismic records, bright spots, phase inversions and other acoustic anomalies indicate that gas and/or fluid escape plays an important role in the formation of these mounds. They are often associated with normal faults that occur along the western slope of the Okinawa Trough, these faults acting as conduits for migrating fluid. Based on regional stratigraphic correlation, we propose that the source of mud and fluid is deeper/older than 235 ka. The seepage process is suspected to be very recent, and probably still active, based on the facts that (1) despite high sedimentation rate, the mounds are not buried by recent sediments, and (2) Last Glacial Maximum deposits are reworked at the emplacement of the mounds. Carbonate-cemented sediments and deep-water reefs possibly associated with fluid seepage could be the origin of local patches of very high backscattering acoustic facies, mapped with the swath bathymetric system.