RV SONNE Fahrtbericht / Cruise Report SO227 TAIFLUX : Fluid and gas migration in the transition from a passive to an active continental margin off SW Taiwan, 02.04. - 02.05.2013, Kaohsiung - Kaohsiung (Taiwan)

RV SONNE Fahrtbericht / Cruise Report SO227 TAIFLUX : Fluid and gas migration in the transition from a passive to an active continental margin off SW Taiwan, 02.04. - 02.05.2013, Kaohsiung - Kaohsiung (Taiwan)
复制标题

RV SONNE Fahrtbericht / 游轮报告 SO227 TAIFLUX：台湾西南部从被动大陆边缘向主动大陆边缘过渡过程中的流体和气体运移，02.04。

DOI：
10.3289/geomar_rep_ns_11_2013
复制
发表时间：
2013
期刊：
Marine Geology
影响因子：
2.9
通讯作者：
C. Berndt
C. Berndt
中科院分区：
地球科学2区
文献类型：
--
作者：
C. Berndt

文献摘要

被引文献

相似文献

SO227的潜在科学动机是限制地质过程 控制着海洋沉积物中水合物的分布和饱和度。最 巡航的一个重要目的是观察附加流体平流沿着的影响 盲冲进入天然气水合物稳定区。与其明确区分为被动式 大陆边缘和活动大陆边缘，台湾西南部地区特别适合这种类型的大陆边缘。 研究，因为它是非常好的研究，它是已知的构造结构， 挤压和俯冲带干扰了原本相当均匀的表层沉积物 的边缘。 在使用多波束回声测深仪和侧扫声纳进行侦察调查后， 选择了两个站点，分别是典型的主动和被动裕度。因为在这两次 我们进行了全面的地球物理实验，包括高分辨率3D 使用P-Cable系统的地震成像，海底地震仪（OBS）部署， 受控源电磁（CSEM）测量、热流测量，以及 使用混合动力和电视抓取进行地面实况调查虽然P-Cable数据使我们能够确定 研究区域的内部结构深入海底以下约500米， OBS和CSEM数据将沿着二维方向约束水合物和游离气饱和度 通过3D地震立方体进行横切。热流数据将提供 关于沉积物的热条件的信息。 第一个地点位于南中国海被动边缘的福尔摩沙海岭。的 山脊是北部、西部和东部峡谷侵蚀的结果。高分辨率三维 地震数据显示，一个连续的底部模拟反射层（BSR）标志着 水合物稳定带的底部。特别是在北部的峡谷下面， 比山脊中心下面浅得多这可能表明峡谷 切割改变了水合物的稳定性场，而深层水合物的形成没有改变 能够适应新的压力和温度条件。 第二个地点包括一个称为四向闭合岭的翻转背斜， 潜在盲冲断层的地表表现。在这一地区， 反射体出现在BSR上方。这一不寻常的观测结果可能表明， 饱和度和沉积物中游离气和天然气水合物的同时存在。评价 OBS和CSEM数据将允许测试这一假设。三维地震数据清楚地表明 流体通过稳定的天然气水合物迁移到海底。 海底录像和取样证实存在持续的甲烷渗漏 在3D地震数据中成像的流体迁移通道上方的福尔摩沙海岭处。他们 还确定在四向闭合脊上至少有一个渗漏， 被释放到另一个地震成像流体迁移路径上方的海洋中。这是 在活动边缘SW发现的第一个具有化能合成生态系统的活动渗漏点 离开台湾。
The underlying scientific motivation of SO227 was to constrain the geological processes that control the distribution and saturation of hydrate in marine sediments. The most important objective of the cruise was to observe the effect of additional fluid advection along blind thrusts into the gas hydrate stability zone. With its clear distinction into a passive margin and an active margin the area SW of Taiwan is particularly well suited for this kind of research because it is very well studied and it is known where the tectonic structures of the compression and subduction zone disturb the otherwise fairly homogeneous surface sediments of the margin. After a reconnaissance survey using multi beam echo sounder and side scan sonar we selected two sites that are typical for the active and passive margin, respectively. At these two sites we carried out comprehensive geophysical experiments including high-resolution 3D seismic imaging with the P-Cable system, ocean bottom seismometer (OBS) deployments, controlled source electromagnetic (CSEM) measurements, heat flow measurements, and ground-truthing using HyBis and TV grab. While the P-Cable data allow us to determine the internal structure of the study areas down to a depth of approximately 500 m below sea floor, the OBS and CSEM data will constrain the hydrate and free gas saturation along twodimensional transect through the 3D seismic cubes. The heat flow data will provide information on the thermal conditions of the sediments. The first site covers the Formosa Ridge on the passive margin of the South China Sea. The ridge is the result of canyon erosion in the north, west, and east. The high-resolution threedimensional seismic data show a continuous bottom simulating reflector (BSR) marking the base of the hydrate stability zone. Particularly, underneath the canyon in the north the BSR is much shallower than underneath the centre of the ridge. This may indicates that the canyon incision has changed the hydrate stability field and that hydrate formation at depth has not been able to adjust to the new pressure and temperature conditions. The second site includes a roll over anticline called Four-Way-Closure Ridge which is the surface expression of an underlying blind thrust. In this area numerous high amplitude reflectors occur above the BSR. This unusual observation may suggest very high gas hydrate saturations and coeval presence of free gas and gas hydrate in the sediments. Evaluation of the OBS and CSEM data will allow to test this hypothesis. The 3D seismic data clearly show fluid migration pathways through the gas hydrate stability to the sea floor. Sea floor video footage and sampling confirmed the presence of on-going methane seepage at the Formosa Ridge above the fluid migration pathway imaged in the 3D seismic data. They also establish that there is at least one seep on the Four-Way-Closure Ridge at which methane is released into the ocean above another seismically imaged fluid migration pathway. This is the first active seep site with chemosynthetic ecosystems discovered on the active margin SW off Taiwan.