Oceanic crustal velocities from laboratory and logging measurements of Integrated Ocean Drilling Program Hole 1256D
Oceanic crustal velocities from laboratory and logging measurements of Integrated Ocean Drilling Program Hole 1256D
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来自综合海洋钻探计划孔 1256D 的实验室和测井测量的海洋地壳速度
DOI：
10.1029/2011gc003750
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
M. Salisbury
中科院分区：
文献类型：
--
作者：
L. Gilbert;M. Salisbury
综合大洋钻探计划（IODP）1256 D孔的钻探和测井为系统研究海洋地球物理学的一个基本问题提供了一个独特的机会：什么影响了海洋地壳的地震结构，孔隙度或成分？在裸眼井或区域折射测量中记录的纵波速度（Vp）将主岩和地壳中的裂缝整合在一起。为了确定裂纹在不同尺度下对Vp的影响，我们首先需要在无裂纹或几乎无裂纹的样品上以实验室Vp的形式获得准确的基础数据。我们在原位压力下测量了46个水饱和样品的Vp，以确定主岩的基线速度。这些新的结果匹配或超过Vp日志在整个大部分的孔，特别是在较低的岩脉和辉长岩，孔隙度低。相比之下，在实验室环境条件下在海上测量的样品，即使在现场压力校正后，Vp始终低于Vp日志。根据不同岩性和相的测井和实验室孔隙度数据的简单模型计算的无裂缝Vp表明，熔岩和上部岩脉中的地壳速度受孔隙度控制。特别是，模型显示熔岩中有显著的大尺度孔隙度，特别是在被确定为裂缝流和角砾岩的部分。然而，随着接近第2 - 3层边界，下部岩脉和辉长岩中的地壳速度越来越受岩石学的控制。
Drilling and logging of Integrated Ocean Drilling Program (IODP) Hole 1256D have provided a unique opportunity for systematically studying a fundamental problem in marine geophysics: What influences the seismic structure of oceanic crust, porosity or composition? Compressional wave velocities (Vp) logged in open hole or from regional refraction measurements integrate both the host rock and cracks in the crust. To determine the influence of cracks on Vp at several scales, we first need an accurate ground truth in the form of laboratory Vp on crack‐free, or nearly crack‐free samples. We measured Vp on 46 water‐saturated samples at in situ pressures to determine the baseline velocities of the host rock. These new results match or exceed Vp logs throughout most of the hole, especially in the lower dikes and gabbros, where porosities are low. In contrast, samples measured at sea under ambient laboratory conditions, had consistently lower Vp than the Vp logs, even after correction to in situ pressures. Crack‐free Vp calculated from simple models of logging and laboratory porosity data for different lithologies and facies suggest that crustal velocities in the lavas and upper dikes are controlled by porosity. In particular, the models demonstrate significant large‐scale porosity in the lavas, especially in the sections identified as fractured flows and breccias. However, crustal velocities in the lower dikes and gabbros are increasingly controlled by petrology as the layer 2‐3 boundary is approached.
影响因子：
3.5
作者：
Koepke, J.;Christie, D. M.;Yamazaki, S.
通讯作者：
Yamazaki, S.