| Abstract: | Most of the world‘s Mississippi Valley-type (MVT) zinc-lead deposits occur in orogenic forelands. We examine tectonic aspects of foreland evolution as part of a broader study of why some forelands are rich in MVT deposits, whereas others are barren. The type of orogenic foreland (collisional versus Andean-type versus inversion-type) is not a first-order control, because each has MVT deposits (e.g., Northern Arkansas, Pine Point, and Cevennes, respectively). In some MVT districts (e.g., Tri-State and Central Tennessee), mineralization took place atop an orogenic forebulge, a low-amplitude (a few hundred meters), long-wavelength (100-200 km) swell formed by vertical loading of the foreland plate. In the foreland of the active Banda Arc collision zone, a discontinuous forebulge reveals some of the physiographic and geologic complexities of the forebulge environment, and the importance of sea level in determining whether or not a forebulge will emerge and thus be subject to erosion. In addition to those on extant forebulges, some MVT deposits occur immediately below unconformities that originated at a forebulge, only to be subsequently carried toward the orogen by the plate-tectonic conveyor (e.g., Daniel‘s Harbour and East Tennessee). Likewise, some deposits are located along syn-collisional, flexure-induced normal and strike-slip faults in collisional forelands (e.g., Northern Arkansas, Daniel‘s Harbour, and Tri-State districts). These findings reveal the importance of lithospheric flexure, and suggest a conceptual tectonic model that accounts for an important subset of MVT deposits-those in the forelands of collisional orogens. The MVT deposits occur both in flat-lying and in thrust-faulted strata; in the latter group, mineralization postdated thrusting in some instances (e.g., Picos de Europa) but may have predated thrusting in other cases (e.g., East Tennessee). |
| Genre: | Article |
| ProdID: | 70025215 |
| Citation Author: | Bradley, D. C.; Leach, D. L. |
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| Citation End Page: | 667 |
| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Mineralium Deposita |
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| Citation Number Of Pages: | 16 |
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| Citation Search Results Text: | Tectonic controls of Mississippi Valley-type lead-zinc mineralization in orogenic forelands; 2003; Article; Journal; Mineralium Deposita; Bradley, D. C.; Leach, D. L. |
| Citation Start Page: | 652 |
| Citation Volume: | 38 |
| Citation Year: | 2003 |
| Type: | citation/reference |
| Text: | Tectonic controls of Mississippi Valley-type lead-zinc mineralization in orogenic forelands; 2003; Article; Journal; Mineralium Deposita; Bradley, D. C.; Leach, D. L. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1007/s00126-003-0355-2 |
| Date Other: | Wed, 1 Jan 2003 00:00 -0600 |
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