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洋中脊轴上的热液循环影响岩石层及上覆海水的化学性质,供养着化合生物群,也是岩石层向海水传递热量的媒介(Slater et al,1980;Stein and Stein,1994;Elderfield and Schultz,1996)。通常认为这个系统中的热液流起源于洋中脊扩张轴处,并由一些离扩张轴较远的断层补给(Lowelletal,1995;Kelley et al,2002;Fisher,2003),但热液系统的结构和规模通常不能直接观察到,而是通过由地球物理条件约束的热模型和地球化学模型推断得到的(Johnson et al,1993;Dunn et al,2000;Lowell and Yao,2002)。使用发生的微震也许能通过揭示热裂缝区说明热液的流动路径,在这些裂缝区域冷水从地壳热岩石中获得热量,另外,一些由岩浆及构造应力作用造成的裂隙增大了这些区域的孔隙度和渗透性。本文指出,东太平洋海隆上得到很好研究的热液喷口场之下的震源群集于一小尺度轴向不连续面附近的垂向管状区域和轴向岩浆房正上方的带内。该浅层管状群集相对于这一段洋脊上热液喷口的分布和温度的位置表明,热液补充量集中在那里是构造破裂引起渗透的结果。另外,我们把位于岩浆房上方的地震带解释为热液破碎区,这表明热液循环可能强烈地沿洋脊轴分布。我们认为,说明热液单元横跨轴走向分布和补给带离轴发散分布的模型可能不适用于快速扩张的东太平洋海隆。
Hydrocarbon circulation on the mid-oceanic ridge axis affects the chemical properties of the rock and overlying seawater and supports the chemical assemblage and is also the medium through which rock layers transfer heat to seawater (Slater et al, 1980; Stein and Stein, 1994; Elderfield and Schultz, 1996). It is generally accepted that the hydrothermal flow in this system originates at the mid-oceanic ridge expansion axis and is supplemented by faults that extend further from the expansion axis (Lowelletal, 1995; Kelley et al, 2002; Fisher, 2003), but the hydrothermal system structure And scale are often not directly observable, but are inferred from thermal and geochemical models constrained by geophysical conditions (Johnson et al, 1993; Dunn et al, 2000; Lowell and Yao, 2002). The use of microseismic events may reveal the hydrothermal fluid pathways by revealing hot-zone fractures where cold water receives heat from the crustal hot rocks and that some fractures caused by magmatic and tectonic stresses increase the porosity of these zones Degree and permeability. This paper points out that the hypocenter beneath the well-studied hydrothermal vents on the eastern Pacific Rim is clustered in a vertical tubular zone near a small-scale axial discontinuity and within the band just above the axial magma chamber. The location of the shallow tubular clusters relative to the distribution and temperature of hydrothermal vents in this segment of the ridge indicates that the concentration of hydrothermal charge is concentrated there as a result of the infiltration caused by the structural rupture. In addition, we interpret the seismic zone located above the magma chamber as a hydrothermal crushing zone, indicating that hydrothermal circulation may strongly distribute along the ridge axis. In our opinion, a model that illustrates the distribution of hydrofluid units across an axis and off-axis divergence of recharge zones may not be suitable for the rapidly expanding East Pacific seamounts.