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Analysis of fractures from borehole televiewer logs in a 500m deep hole at Xiaguan, Yunnan province, Southwest China

Physics and Chemistry of the Earth

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Abstract

Fractures from a 500 m deep hole in the Red River fault zone were analyzed using an ultrasonic borehole televiewer. Four hundred and eighty individual fractures were identified between 19 m and 465 m depth. Fracture frequency had no apparent relation to the major stratigraphic units and did not change systematically with depth. Fracture orientation, however, did change with stratigraphic position. The borehole intersected 14 m of Cenozoic deposits, 363 m of lower Ordovician clastic sediments, and 106 m of older ultramafic intrusions. The clastic sequence was encountered again at a depth of 484 m, suggesting a large fault displacement. Fractures in the top 162 m of the sedimentary section appear randomly distributed. Below that depth, they are steeply dipping with northerly and north-westerly strikes, parallel to the major active faults in the region. Fractures in the ultramafic section strike roughly eastwest and are steeply dipping. These orientations are confined to the ultramafic section and are parallel to an older, inactive regional fault set. ?? 1990.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Analysis of fractures from borehole televiewer logs in a 500m deep hole at Xiaguan, Yunnan province, Southwest China
Series title:
Physics and Chemistry of the Earth
Volume
17
Issue:
C
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Physics and Chemistry of the Earth
First page:
199
Last page:
206
Number of Pages:
8