| Abstract: | The continental interior platform of the United States is that part of the North American craton where a thin veneer of Phanerozoic strata covers Precambrian crystalline basement. N- to NE-trending and W- to NW-trending fault zones, formed initially by Proterozoic/Cambrian rifting, break the crust of the platform into rectilinear blocks. These zones were reactivated during the Phanerozoic, most notably in the late Palaeozoic Ancestral Rockies event and the Mesozoic-Cenozoic Laramide orogeny - some remain active today. Dip-slip reactivation can be readily recognized in cross section by offset stratigraphic horizons and monoclinal fault-propagation folds. Strike-slip displacement is hard to document because of poor exposure. Through offset palaeochannels, horizontal slip lineations, and strain at fault bends locally demonstrate strike-slip offset, most reports of strike-slip movements for interior-platform faults are based on occurrence of map-view belts of en echelon faults and anticlines. Each belt overlies a basement-penetrating master fault, which typically splays upwards into a flower structure. In general, both strike-slip and dip-slip components of displacement occur in the same fault zone, so some belts of en echelon structures occur on the flanks of monoclinal folds. Thus, strike-slip displacement represents the lateral components of oblique fault reactivation: dip-slip and strike-slip components are the same order of magnitude (tens of metres to tens of kilometres). Effectively, faults with strike-slip components of displacement act as transfers accommodating jostling of rectilinear crustal blocks. In this context, the sense of slip on an individual strike-slip fault depends on block geometry, not necessarily on the trajectory of regional ??1. Strike-slip faulting in the North American interior differs markedly from that of southern and central Eurasia, possibly because of a contrast in lithosphere strength. Weak Eurasia strained significantly during the Alpine-Himalayan collision, forcing crustal blocks to undergo significant lateral escape. The strong North American craton strained relatively little during collisional-convergent orogeny, so crustal blocks underwent relatively small displacements. |
| Genre: | Article |
| ProdID: | 70025614 |
| Citation Author: | Marshak, S.; Nelson, W. J.; McBride, J. H. |
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| Citation End Page: | 184 |
| Citation Issue: | 210 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geological Society Special Publication |
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| Citation Number Of Pages: | 26 |
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| Citation Search Results Text: | Phanerozoic strike-slip faulting in the continental interior platform of the United States: Examples from the Laramide Orogen, midcontinent, and Ancestral Rocky Mountains; 2003; Article; Journal; Geological Society Special Publication; Marshak, S.; Nelson, W. J.; McBride, J. H. |
| Citation Start Page: | 159 |
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| Citation Year: | 2003 |
| Type: | citation/reference |
| Text: | Phanerozoic strike-slip faulting in the continental interior platform of the United States: Examples from the Laramide Orogen, midcontinent, and Ancestral Rocky Mountains; 2003; Article; Journal; Geological Society Special Publication; Marshak, S.; Nelson, W. J.; McBride, J. H. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 2003 00:00 -0600 |
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