| Abstract: | Regional sets of steeply dipping joints and faults are common throughout the Sierra Nevada batholith, yet relatively little is known about how or when they formed. Within some east-northeast-striking, left-lateral fault zones in the Mount Abbot quadrangle of the central Sierra Nevada, the host granodiorite is hydrothermally altered to a lower greenschist assemblage that contains muscovite. The muscovite yields a mean K-Ar and 40Ar/39Ar age of 79 Ma, which provides a minimum age for the faulting. Field relations show that these faults developed from earlier formed, mineralized joints, so these ages also provide a minimum age for the jointing. Published ages of biotite, hornblende, and zircon from the host granodiorite of Lake Edison are 80 Ma (K-Ar), 85 Ma (K-Ar), and 90 Ma (U-Pb), respectively. The geochronology, field relations, and hydrothermal mineral assemblages together suggest that the mineralized joints and faults all formed between 85 and 79 Ma, soon after the host pluton was emplaced. -Authors |
| Genre: | Article |
| ProdID: | 70015930 |
| Citation Author: | Segall, P.; McKee, E. H.; Martel, S. J.; Turrin, B. D. |
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| Citation End Page: | 1257 |
| Citation Issue: | 12 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geology |
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| Citation Number Of Pages: | 10 |
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| Citation Search Results Text: | Late Cretaceous age of fractures in the Sierra Nevada batholith, California; 1990; Article; Journal; Geology; Segall, P.; McKee, E. H.; Martel, S. J.; Turrin, B. D. |
| Citation Start Page: | 1248 |
| Citation Volume: | 18 |
| Citation Year: | 1990 |
| Type: | citation/reference |
| Text: | Late Cretaceous age of fractures in the Sierra Nevada batholith, California; 1990; Article; Journal; Geology; Segall, P.; McKee, E. H.; Martel, S. J.; Turrin, B. D. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1990 00:00 -0600 |
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