Title: Different thrust belts and foredeeps in a global perspective
Abstract: Looking at tectonics from a global perspective may open new horizons in the structural studies of thrust belts as well as other tectonic settings. Inferences from plate motions over the past 40 m.y., based on structural data, indicate the presence of a coherent flow of plate motions. Moreover, a [open quotes]westward[close quotes] drift of the lithosphere relative to the asthenosphere is indicated by plate motions in the hot-spot reference frame. Independent geological observations such as the different styles of deformation in thrust belts associated with subduction following or opposing the relative [open quotes]eastward or northeastward[close quotes] mantle flow also support this global polarity, both in the general directions and in the [open quotes]westward[close quotes] component. Because of this, thrust belts related to east-northeast-dipping subduction show conspicuous structural and morphologic relief, involve deep crustal rocks, and are associated with shallow foredeeps. However, thrust belts related to west-dipping subduction show relatively low structural and morphological relief; they involve only shallow upper crustal rocks and are associated with deep foredeeps as well as back-arc extensions. In the case of west-dipping subduction, the area of the foredeep (filled or unfilled) is bigger than the area of the associated elevated orogene, and it is smallermore » in the opposite subduction. For this reason, in west-dipping subductions in the foredeep maintains longer conditions of deep sea facies with respect to the opposite end member. Foredeep depth in west-dipping subductions is controlled mainly by the rollback of the subduction hinge pushed by the relative [open quotes]eastward[close quotes] mantle flow, and foredeep depth in east- or northeast-dipping subductions is generated mainly by the load of the thrust sheets and by the rollback of the subduction hinge due to the advancing upper plate, contrasting the upward push of the mantle.« less
Publication Year: 1993
Publication Date: 1993-11-01
Language: en
Type: article
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