Permeability versus depth in the upper oceanic crust: In situ measurements in DSDP hole 504B, eastern equatorial Pacific

Anderson, Roger N.; Zoback, Mark D.; Hickman, Stephen H.; Newmark, R. L.

doi:10.1029/jb090ib05p03659

Cited by 112 publications

(95 citation statements)

References 21 publications

(18 reference statements)

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“…Within Layer 2C, the good agreement between the core mea surements and the model at porosity values of the order of 0.1% is compatible with the low values of permeability mea sured in situ (Anderson et al, 1985b;Becker, 1985, this vol ume). At the base of Layer 2B (600 to 850 mbsf), however, the agreement at values around 3.0% becomes questionable, as similar low values of permeability were obtained in situ.…”

Section: Discussionmentioning

confidence: 50%

“…comm., 1988;Pezard et al, this volume). The locations of breccias observed in cores (from Shipboard Scientific Party, 1988), alteration boundaries (from , and large-scale seis mic layers (from Anderson et al, 1985b) are plotted for reference.…”

Section: Discussionmentioning

confidence: 99%

“…7A; Gable et al, this volume) shows that the bottom of Unit 2D precisely defines the depth at which the temperature starts to increase rapidly as the ocean wa ter enters the underpressured aquifer (Anderson and Zoback, 1982;Anderson et al, 1985b), which is the upper limit of the zone of water intake into the crust. The temperature gradient re corded during Leg 111 (Fig.…”

Section: Layer 2amentioning

confidence: 99%

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Morphology and Alteration of the Upper Oceanic Crust from In-Situ Electrical Experiments in DSDP/ODP Hole 504B

Pézard¹,

Anderson²

1989

Proceedings of the Ocean Drilling Program

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During ODP Leg 111, the drillship JOIDES Resolution returned to DSDP Hole 504B, on the south flank of the Costa Rica Rift. The main objective of Leg 111 was the study of the physical and chemical structure of young oceanic crust in the deepest hole yet drilled into the oceanic crust. In addition to the drilling of an additional 212.3 m into the massive units of Layer 2C, Leg 111 provided the opportunity to conduct an extensive suite of in-situ experiments, in cluding the recording of a continuous electrical resistivity profile, from which total and fracture porosity estimates were computed. This allowed us to discriminate the large-scale layers of the crust, to isolate individual lithologic units (such as pillows and massive flows), and to describe the overall morphology of the upper crust.In the extrusive part of the crust, certain massive flows (> 10 m thick) appear to be permeability barriers that subse quently constrain fluid circulation. We interpret the flows of Unit 2D as the upper limit of an underpressured aquifer located within Layer 2A and Unit 27 as the boundary between low-temperature, seawater alteration facies of basalt and higher temperature alteration phases. This relationship between morphology and hydrological regime, and therefore al teration of the basaltic basement, might be viewed as related to the accretion process of the upper oceanic crust. The presence of fractures can be attributed in most cases to thermal stresses from the cooling of a nearby unit or to tectonic features such as the inferred listric fault at about 4300 m below rig floor (825 m below seafloor). The porosity estimate obtained from the analysis of in-situ measurements is (1) reduced in accounting for clay conduction via cation exchange mechanisms, (2) constant over long sections of the drill hole, and (3) observed to decrease by steps with increasing depth. The extremely low values of porosity computed in the dikes indicate a slow regime of hydrothermal circulation deep into the crust and correlate with the low values of in-situ permeability deduced from packer experiments.

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Section: Discussionmentioning

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Section: Layer 2amentioning

confidence: 99%

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Morphology and Alteration of the Upper Oceanic Crust from In-Situ Electrical Experiments in DSDP/ODP Hole 504B

Pézard¹,

Anderson²

1989

Proceedings of the Ocean Drilling Program

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“…In the constant-rate injection tests, borehole pressure was monitored as fluids were pumped into the formation at a constant rate andduring the subsequent pressure recovery. The methods used are similar to those described by Anderson and Zoback (1982), Hickman et al (1984), Anderson et al (1985), and Becker (1989Becker ( , 1991 when conducting packer experiments in Holes 395A and 504B for the Deep Sea Drilling Project (DSDP) and ODP. In general, slug tests are most useful for low-permeability formations, but decay too quickly to be analyzed in high-permeability formations.…”

Section: Test Proceduresmentioning

confidence: 99%

In Situ Permeability Tests at Site 892: Characteristics of a Hydrogeologically Active Fault Zone on the Oregon Accretionary Prism

Screaton¹,

Carson²,

Lennon³

1995

Proceedings of the Ocean Drilling Program, 146 Part 1 Scientific Results

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“…In the case of Hole 504B, a systematic program of packer testing has been performed during Legs 69,83,92,and 111. These data provide a representation of the vertical distribution of bulk permeability in the oceanic crust at this site to 1500 mbsf (Anderson et al, 1985;Becker et al, 1989).…”

Section: Flowmeter Experimentsmentioning

confidence: 99%

Explanatory Notes

1992

Proceedings of the Ocean Drilling Program

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Permeability versus depth in the upper oceanic crust: In situ measurements in DSDP hole 504B, eastern equatorial Pacific

Cited by 112 publications

References 21 publications

Morphology and Alteration of the Upper Oceanic Crust from In-Situ Electrical Experiments in DSDP/ODP Hole 504B

Morphology and Alteration of the Upper Oceanic Crust from In-Situ Electrical Experiments in DSDP/ODP Hole 504B

In Situ Permeability Tests at Site 892: Characteristics of a Hydrogeologically Active Fault Zone on the Oregon Accretionary Prism

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