浅谈深水块体搬运复合体的结构、成因分类以及识别方法

Mass-Transport Complexes (MTCs) are important components of deep-water systems, and widely distributed in continental margins and lake basins. Understanding MTCs is helpful for expanding the targets of deep-water hydrocarbon exploration and for evaluating geological risks of subsea engineering. Typical MTCs consist of three parts: the head tension area, body slip area, and toe compression area. During the transportation of MTCs, these three domains come into being successively. MTCs can be classified into three types: slide rock, slump rock, and debris rock, based on the sediment transport process and fluid properties, and they respectively correspond to elastic deformation, elastic and plastic deformation and plastic deformation stages. In 3D seismic plan, according to the direction of sediment flow (the slope direction), some depositional elements of MTCs, such as head cliffs, body folds, and toe squeeze ridges, can be clearly identified in proper order, and in seismic profiles MTCs are characterized by weak-medium amplitude reflections, mound-like shapes, and irregular top/bottom interfaces. In conventional log data, MTCs are commonly responded as abrupt shifts at their top/bottom interfaces. In outcrop data, MTCs have several kinds of sedimentary structures, such as massive textures, sliding folds, and mud lumps. Compared with turbidites, MTCs have many distinct characteristics. For example, MTCs are deposited from sediments transported through a "frozen" manner and have an "elongate-fan-like" slope morphology, a relative large thickness. Furthermore, MTCs can be characterized by no obvious features of grading differentiation and relatively large stratigraphic dips.

Keywords： Deep-water mass-transport complexes ; Sedimentary structure ; Genetic classification ; Identification marks