thumbnail

Ultrasonic borehole televiewer investigation of oceanic crustal layer 2A, Costa Rice Rift

Nature

By:
,
DOI: 10.1038/295375a0

Links

Abstract

In situ lithostratigraphy and the distribution of fracture and void zones in oceanic layer 2A were examined with an ultrasonic borehole televiewer at IPOD sites 501 and 504B on the south flank of the Costa Rice Rift. These records indicate a decrease in the size of basalt pillows with depth and a corresponding increase in fracture and void density. The observed increase in P-wave velocity with depth in this hole, as layer 2A merges into 2B, is best explained by an increase in the degree to which clays and zeolites fill fractures and voids. This also explains the order-of-magnitude drop in permeability observed in hole 504B. An increase in alteration-filling with age could explain the transition from convective to conductive heat flow and the correlative disappearance of layer 2A on the flanks of oceanic spreading centres. ?? 1982 Nature Publishing Group.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Ultrasonic borehole televiewer investigation of oceanic crustal layer 2A, Costa Rice Rift
Series title:
Nature
DOI:
10.1038/295375a0
Volume
295
Issue:
5848
Year Published:
1982
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Nature
First page:
375
Last page:
379
Number of Pages:
5