A thermoconvective interpretation of heat flow data in the area of Ocean Drilling Program Leg 116 in a distal part of the Bengal Fan
A thermoconvective interpretation of heat flow data in the area of Ocean Drilling Program Leg 116 in a distal part of the Bengal Fan
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孟加拉扇远端海洋钻探计划第 116 段区域热流数据的热对流解释
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
P. Genthon
中科院分区：
文献类型：
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作者：
A. Ormond;J. Boulègue;P. Genthon
本文给出了孟加拉扇远端沉积堆内热对流环流的数值模拟研究结果。断层的出现和地表热流数据的变异性使以前的工作人员认为这一地区存在热液循环。根据大洋钻探计划第116段调查的目的，收集了足以限制理解和量化洋盆热流和孔隙流体循环之间关系的模型的数据。本文将沉降桩模拟为各向异性倾斜的多孔层，断层间断，呈周期性分布。该模型试图再现的一个重要观测结果是，热流最大值的表面表达式与718站点附近的断裂带之间的位移约为2-3公里。分析了各断裂带内渗透率各向异性和渗透率的影响。当断裂带的最大垂直渗透率大于多孔块体垂直渗透率的5倍时，环流由纵向滚动(即轴向下倾的滚动)组成，断裂带对流更强烈。当断裂带的最大渗透率比多孔层的垂直渗透率大10倍或更多时，对流主要局限于断层面。在所有情况下，最大热流值都位于断层的正上方。结果表明，在水平和垂直陡坡上，沉积物的−1强迫对流和渗透率分别为0.5Darcy(5×10−13m2)和5mdarcy，这两个数据之间的一致性最好。
We present the results of a numerical simulation study of the thermo-convective circulation in a sedimentary pile, in the distal part of the Bengal Fan. The occurrence of faults and the variability of surface heat flow data led previous workers to suggest hydrothermal circulation in this area. According to the purpose of Ocean Drilling Program survey Leg 116, data were collected which are adequate to constrain a model for the comprehension and the quantification of the relationship between ocean basin heat flow and pore fluid circulation. In this paper the sedimentary pile is modeled as an anisotropic and inclined porous layer interrupted by faults with a periodic distribution. An important observation the model tries to reproduce is the shift of approximately 2–3 km between the surface expression of the heat flow maximum and the fault zone near site 718. The influence of permeability anisotropy and of permeability within those fault zones is analyzed. When the maximum vertical permeability in the fault zones is 5 times greater than the vertical permeability of the porous block, the circulation consists of longitudinal rolls (i.e., rolls with their axis oriented downslope), with more vigorous convection in fault zones. When the maximum permeability of the fault zone is 10 or more times greater than the vertical permeability of the porous layer, convection is primarily restricted to the fault plane. In all cases maximum heat flow values are located directly above faults. This paper shows that the best agreement between those data suggests a 1 m yr−1 forced convection and a permeability of the sediments of 0.5 darcy (5 × 10−13 m2) and 5 mdarcy respectively, in the horizontal and vertical derictions.