Multi-scalar structure at DSDP/ODP Site 504, Costa Rica Rift. III: faulting and fluid circulation. Constraints from integration of FMS images, geophysical logs and core data

被引：4

作者：

Ayadi, M ^{[1
]}

Pezard, PA ^{[1
]}

Bronner, G ^{[1
]}

Tartarotti, P ^{[1
]}

Laverne, C ^{[1
]}

机构：

[1] CEREGE, CNRS, UMR 6635, F-13545 Aix En Provence, France

来源：

CORE-LOG INTEGRATION | 1998年 / 136卷

关键词：

D O I：

10.1144/GSL.SP.1998.136.01.26

中图分类号：

P5 [地质学];

学科分类号：

0709 ; 081803 ;

摘要：

Downhole geophysical logs and high-resolution electrical images (FMS) from DSDP/ODP Hole 504B are analysed in combination with core data to obtain an integrated description of oceanic faults met in the hole. About 34 500 fractures were mapped from FMS images over 1672 m of basement. The fracture distribution from FMS confirms the presence of a main fault zone between 800 and 1100 mbsf (metres below sea floor), elsewhere detected from seismic data as well as magnetic, acoustic, and electrical resistivity measurements. The fracture density profile reveals the presence of two other highly fractured zones, (1) between 400 and 575 mbsf and (2) close to the bottom of Hole 504B (1700 to 2100 mbsf). Consequently, we infer that Site 504 was submitted first to an extensional stress regime near the ridge axis: with circulation of high-temperature fluids and pervasive alteration of the basalts. This initial phase is associated with the main fault met in Hole 504B. Similar but less developed deformation was generated off-axis, with lower-temperature parageneses, such as that cored between 400 and 575 mbsf. The present compressional to strike-slip stress regime is expressed in subhorizontal fracturing detected in discrete zones, such as within the main fault zone and the lower fracture zone (1700 to 2100 mbsf) in Hole 504B.

引用

页码：311 / 326

页数：16

共 48 条

[1]

Agar S.M., Fracture evolution in the upper ocean crust: Evidence from DSDP hole 504B, Deformation Mechanisms, Rheology and Tectonics, 54, pp. 41-50, (1990)

[2]

Microstructural evolution of a deformation zone in the upper ocean crust: Evidence from DSDP Hole 504B, Journal of Geodynamics, 13, pp. 119-140, (1991)

[3]

Klitgord K.D., A mechanism for decoupling within the oceanic lithosphere revealed in the Troodos ophiolite, Nature, 374, pp. 232-238, (1995)

[4]

Alt J.C., Laverne C., Muehlenbachs K., Alteration of the upper oceanic crust: Mineralogy and processes in Deep Sea Drilling Project Hole 504B, Initial Reports of the Deep Sea Drilling Project, 83, pp. 217-248, (1985)

[5]

Honnorez J., Laverne C., Emmermann R., Hydrothermal alteration of a 1 km section through the upper oceanic crust, DSDP hole 504B: The mineralogy, chemistry and evolution of seawater-basalt interactions, Journal of Geophysical Research, 91, pp. 309-335, (1986)

[6]

Kinoshita H., Stokking L.B., Et al., Proceedings of the Ocean Drilling Program. Initial Reports, 148, (1993)

[7]

Teagle D.A.H., Laverne C., Vanko D.A., Bach W., Honnorez J., Becker K., Ayadi M., Pezard P.A., Ridge flank alteration of upper ocean crust in the Eastern Pacific: Synthesis of results for volcanic rocks of Holes 504B and 896A, Proceedings of the Ocean Drilling Program, Scientific Results, 148, pp. 435-450, (1996)

[8]

Anderson R.N., Honnorez J., Becker K., Adamson A.C., Alt J.C., Emmermann R., Kempton P.D., Kinoshita H., Laverne C., Mottl M.J., Newmark R.L., DSDP Hole 504B, The first reference section over 1 km through Layer 2 of the oceanic crust, Nature, 300, pp. 589-594, (1982)

[9]

Et al., Initial Reports of the Deep Sea Drilling Project, 83, (1985)

[10]

Ayadi M., Pezard P.A., De Larouziere F.D., Fracture distribution from downhole electrical images at the base of the sheeted dike complex in DSDP/ODP Hole 504B, Proceedings of the Ocean Drilling Program, Scientific Results, 148, pp. 307-315, (1996)

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