| Abstract: | The Helena-Haystack melange (HH melange) and coincident Darrington-Devils Mountain fault zone (DDMFZ) in northwestern Washington separate two terranes, the northwest Cascade System (NWCS) and the western and eastern melange belts (WEMB). The two terranes of Paleozoic and Mesozoic rocks superficially resemble each other but record considerable differences in structural and metamorphic history. The HH melange is a serpentinite-matrix melange containing blocks of adjacent terranes but also exotic blocks. The HH melange must have formed between early Cretaceous and late middle Eocene time, because it contains tectonic clasts of early Cretaceous Shuksan Greenschist and is overlain by late middle Eocene sedimentary and volcanic rocks. The possible continuation of the DDMFZ to the northwest as the San Juan and the West Coast faults on Vancouver Island suggests that the structure has had a major role in the emplacement of all the westernmost terranes in the Pacific Northwest. -from Author |
| Genre: | Article |
| ProdID: | 70018037 |
| Citation Author: | Tabor, R. W. |
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| Citation End Page: | 232 |
| Citation Issue: | 2 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geological Society of America Bulletin |
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| Citation Number Of Pages: | 16 |
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| Citation Search Results Text: | Late Mesozoic and possible early Tertiary accretion in western Washington State: the Helena-Haystack melange and the Darrington- Devils Mountain fault zone; 1994; Article; Journal; Geological Society of America Bulletin; Tabor, R. W. |
| Citation Start Page: | 217 |
| Citation Volume: | 106 |
| Citation Year: | 1994 |
| Type: | citation/reference |
| Text: | Late Mesozoic and possible early Tertiary accretion in western Washington State: the Helena-Haystack melange and the Darrington- Devils Mountain fault zone; 1994; Article; Journal; Geological Society of America Bulletin; Tabor, R. W. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
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