The permeability of young oceanic crust east of Juan de Fuca Ridge determined using borehole thermal measurements
The permeability of young oceanic crust east of Juan de Fuca Ridge determined using borehole thermal measurements
复制标题
DOI：
10.1029/97gl01286
复制
发表时间：
1997-06-01
影响因子：
5.2
通讯作者：
Davis, EE
中科院分区：
文献类型：
--
作者：
Fisher, AT;Becker, K;Davis, EE
在大洋钻探计划(ODP)1026b孔中进行的温度测量，该孔在3.5英里内钻入了一个被沉积物埋藏的地下室山脊。胡安德·富卡山脊东侧的古老地壳揭示了流体从地层流入上覆海洋的情况。这一流动表明，该地点的上玄武岩地壳相对于流体静力是自然超压的。这一发现与以前发表的上地壳水热循环数值模型的结果是一致的，该模型包括适当的地壳几何形状、沉积物厚度和基础热流。流入1026b孔的流体通过沉积物-基底接触面下方上部10米的玄武岩进入孔内。根据热数据估计的流速(80-120米/小时)，结合推断的相对于流体静力的基底超压(约20-30千帕)，被用来估计最浅洋壳的体积渗透率：5至9×10(-12)米(2)。如此高的体积渗透率将允许区域显著的热液循环，这与该地区上基底的热均一性一致。
Temperature measurements made in Ocean Drilling Program (ODP) Hole 1026B, drilled into a sediment-buried basement ridge in 3.5 m.y. old crust on the eastern flank of Juan de Fuca Ridge, revealed fluid flow from the formation and into the overlying ocean. This flow indicates that the upper basaltic crust at this site is naturally overpressured relative to hydrostatic. This finding is consistent with output from previously published numerical models of hydrothermal circulation in the upper crust that include appropriate crustal geometry, sediment thickness,;and basal heat flow. The fluid flowing into Hole 1026B enters the hole through the upper 10 m of basalt below the sediment-basement contact. The flow rate estimated from the thermal data (80-120 m/hr), in combination with the inferred basement overpressure relative to hydrostatic (about 20-30 kPa), was used to estimate the bulk permeability of the shallowest oceanic crust: 5 to 9 x 10(-12) m(2). Such high bulk permeability would allow regionally significant hydrothermal circulation, consistent with thermal homogenization of upper basement in this area.