| Abstract: | In southeastern Alaska, granodiorite-tonalite plutons of the Admiralty-Revillagigedo belt intruded the Jurassic-Cretaceous Gravina belt along the eastern side of the Alexander terrane around 90 Ma. These plutons postdate some deformation related to a major contractional event between the previously amalgamated Wrangellia and Alexander terranes and the previously accreted terranes of the North American margin. We studied the aureole mineral assemblages of these plutons near Petersburg, Alaska, determined pressure and temperature of equilibration, and examined structures that developed within and adjacent to these plutons. Parallelism of magmatic and submagmatic fabrics with fabrics in the country rock indicates synchroneity of pluton emplacement with regional deformation and suggests that magma transport to higher crustal levels was assisted by regional deformation. Replacement of andalusite by kyanite or sillimanite indicates crustal thickening soon after pluton emplacement. Regional structural analysis indicates the crustal thickening was accomplished by thrust burial. Thermobarometric analyses indicate the aureoles reached near-peak temperatures of 525 to 635 ??C at pressures of 570 to 630 MPa. Consideration of the rate of thermal decay of the aureoles suggests that burial was rapid and occurred at rates around 5 to 8 mm/year. Structural observations indicate there was contractional deformation before, during, and after emplacement of the 90-Ma plutons. Initial exhumation of the Admiralty-Revillagedo belt in the Petersburg area may have occurred along a thrust west of the pluton belt within the Gravina belt. ?? 2004 NRC Canada. |
| Genre: | Article |
| ProdID: | 70027147 |
| Citation Author: | Himmelberg, G. R.; Haeussler, P. J.; Brew, D. A. |
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| Citation End Page: | 102 |
| Citation Issue: | 1 |
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| Citation Language: | English |
| Citation Larger Work Title: | Canadian Journal of Earth Sciences |
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| Citation Number Of Pages: | 16 |
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| Citation Search Results Text: | Emplacement, rapid burial, and exhumation of 90-Ma plutons in southeastern Alaska; 2004; Article; Journal; Canadian Journal of Earth Sciences; Himmelberg, G. R.; Haeussler, P. J.; Brew, D. A. |
| Citation Start Page: | 87 |
| Citation Volume: | 41 |
| Citation Year: | 2004 |
| Type: | citation/reference |
| Text: | Emplacement, rapid burial, and exhumation of 90-Ma plutons in southeastern Alaska; 2004; Article; Journal; Canadian Journal of Earth Sciences; Himmelberg, G. R.; Haeussler, P. J.; Brew, D. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1139/e03-087 |
| Date Other: | Thu, 1 Jan 2004 00:00 -0600 |
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