Gas hydrate in the Green Canyon area (Block 955) in the northern Gulf of Mexico is hosted by relatively clay-free silty levee deposits bounding a Pleistocene submarine channel. During the initial phase of channel development, the channel axis experienced sediment bypass while silty to sandy flanking levees formed. Development of high levees prompted gravitational collapse along normal faults dipping toward the channel axis. Extension at the levees was accompanied by compression at the channel axis. The gravitational failure caused rotation and displacement of the levee deposits. Later, deposition occurred within channel axis, whereas only fine-grained sediments accumulated on the levees. The change in depositional style is interpreted as the result of reduced height and strength of the turbidity currents moving along the channel at the later stage, which restricted most nonclay fraction sediments to the levee-confined channel. There is no gravitational failure in this stage, probably because relief between the levee crest and channel floor was reduced because of deposition within the channel. The hydrates are almost entirely restricted to the clay-poor levee deposits formed during the early stage of channel development, with minor hydrate accumulation in late-stage channel axial deposits. The silty levee reservoir is compartmentalized because of the presence of gravitational failure surfaces and an extensive network of salt-related normal faults. The results of this predominantly seismic stratigraphic study completed as a part of The University of Texas at Austin/US Department of Energy Deep-Water Methane Hydrate Characterization and Scientific Assessment project should be compared with sedimentological information from analysis of pressurized cores obtained during The University of Texas-Gulf of Mexico 2-1 (UT-GOM2-1) Hydrate Pressure Coring Expedition presented elsewhere in this volume.

中文翻译：

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深海墨西哥湾含天然气水合物的深水河道-堤防系统演化：堤防生长变形

墨西哥湾北部 Green Canyon 地区（955 区块）的天然气水合物位于更新世海底通道边界的相对不含粘土的粉砂质堤坝沉积物中。在河道开发的初始阶段，河道轴线经历了沉积物旁路，同时形成了粉质至沙质的侧翼堤坝。高堤的发展促使沿正常断层向河道轴倾斜的重力坍塌。堤坝的扩张伴随着河道轴的压缩。重力破坏导致堤坝沉积物发生旋转和位移。后来，河道轴线内发生沉积，而堤坝上仅堆积细粒沉积物。沉积样式的变化被解释为后期沿河道移动的浊流的高度和强度降低的结果，这将大多数非粘土部分沉积物限制在堤坝限制的河道中。此阶段没有重力破坏，可能是因为河道内沉积导致堤坝和河床之间的起伏减少。水合物几乎完全局限于河道发育早期形成的贫粘土堤坝沉积，晚期河道轴向沉积有少量水合物聚集。由于存在重力破坏面和与盐有关的正断层的广泛网络，粉砂质堤坝被分隔开。