TY - JOUR
T1 - Mechanism of exfoliation joint formation in granitic rocks, Yosemite National Park
AU - Bahat, Dov
AU - Grossenbacher, Ken
AU - Karasaki, Kenzi
N1 - Funding Information:
This work was carried out under U.S. Department of Energy Contract No. DEAC03-76SF00098 for the Director, Office of Civilian Radioactive Waste Management, Office of External Relations, and was administered by the Nevada Operations Office, U.S. Department of Energy. This work was also partially supported by the Power Reactor and Nuclear Fuel Development Corporation of Japan. We thank Sally Benson, Bo Bodvarsson, and Paul Witherspoon for their facilitation of the project. Special thanks are due for Pascual Benito for his work on the figures. Finally, we wish to thank David Peacock, Stephen Laubach, Patience Cowie, an unnamed referee, Richard Lisle and Chaim Benjamini for their thoughtful and detailed reviews of our material.
PY - 1999/1/1
Y1 - 1999/1/1
N2 - Fractographic techniques reveal mechanical aspects of exfoliation in granitic rocks at Yosemite National Park, and electronic surveying provides information on their attitudes and dimensions. In the middle elevations of the cliff of El Capitan, exfoliation consists of early fractures a few meters to tens of meters in size which are fan-shaped. Fans at upper elevations point upwards, whereas fans at lower elevations point downwards parallel to the cliff. The fans interact with each other and merge into composite joints hundreds of meters in size, normal to the minimum compressive principal stress. This polarity indicates exfoliation by longitudinal splitting and buckling. The palaeostress causing the exfoliation on the southwestern side of Half Dome is estimated to range between 0.01 MPa and 0.94 MPa. Differences in fracture paleostresses of joints may be used in comparing their relative propagation velocities. It is suggested that the large exfoliation on the southwestern side of Half Dome had undergone a prolonged sub-critical growth before attaining rapid fracture velocities under post-critical conditions.
AB - Fractographic techniques reveal mechanical aspects of exfoliation in granitic rocks at Yosemite National Park, and electronic surveying provides information on their attitudes and dimensions. In the middle elevations of the cliff of El Capitan, exfoliation consists of early fractures a few meters to tens of meters in size which are fan-shaped. Fans at upper elevations point upwards, whereas fans at lower elevations point downwards parallel to the cliff. The fans interact with each other and merge into composite joints hundreds of meters in size, normal to the minimum compressive principal stress. This polarity indicates exfoliation by longitudinal splitting and buckling. The palaeostress causing the exfoliation on the southwestern side of Half Dome is estimated to range between 0.01 MPa and 0.94 MPa. Differences in fracture paleostresses of joints may be used in comparing their relative propagation velocities. It is suggested that the large exfoliation on the southwestern side of Half Dome had undergone a prolonged sub-critical growth before attaining rapid fracture velocities under post-critical conditions.
UR - http://www.scopus.com/inward/record.url?scp=0033009034&partnerID=8YFLogxK
U2 - 10.1016/S0191-8141(98)00069-8
DO - 10.1016/S0191-8141(98)00069-8
M3 - Article
AN - SCOPUS:0033009034
SN - 0191-8141
VL - 21
SP - 85
EP - 96
JO - Journal of Structural Geology
JF - Journal of Structural Geology
IS - 1
ER -