Dynamic processes controlling foreland development – the role of mechanical (de)coupling of orogenic wedges and forelands

Abstract

Abstract. Depending on the polarity of the subduction system controlling the evolution of an orogenic wedge, we distinguish between pro-wedge (fore-arc, foreland) and retrowedge (retro-arc, hinterland) forelands. Flexural foreland basins and/or intraplate compressional structures can develop in retro-wedge domains of Andean-type and in pro-and retro-wedge domains of Himalayan-type orogens.Whereas the subsidence of retro-wedge foreland basins is exclusively controlled by the topographic load exerted by the orogenic wedge on the foreland lithosphere, the additional load of the subducted lithospheric slab contributes towards the subsidence of pro-wedge foreland basins. Flexural forebulges develop only if the orogenic wedge and the foreland lithosphere are mechanically decoupled at lithospheric levels.Under conditions of mechanical coupling between an orogenic wedge and its foreland at crustal and/or mantlelithospheric levels, compressional stresses are transmitted into the latter, inducing reactivation of pre-existing crustal discontinuities and broad crustal and lithosphere scale folding at distances up to 1700 km from the collision front. Such stresses can accentuate potential pre-existing flexural forebulges or impede their development. Depending on the thickness and rheological structure of the crust and its sedimentary cover, thick-and/or thin-skinned thrusts can propagate far into forelands, either disrupting pre-existing flexural foreland basins or impeding their development.Collision-related compressional stresses can be transmitted into pro-wedge forelands during 1) initiation of subduction zones, 2) periods of subduction impediment caused by the arrival of more buoyant crust at a subduction zone, 3) initial collision of an orogenic wedge with a passive margin, and 4) post-collisional over-thickening and uplift of an orogenic wedge and the development of a mantle-back-stop.Development of intraplate compressional/transpressional structures in forelands is indicative for the build-up of collision-related compressional stresses, and thus for strong Correspondence to: P. A. Ziegler (fax +41-061-421.55.35) mechanical coupling of a foreland with the associated orogenic wedge, either at crustal and/or mantle-lithospheric levels. The absence of syn-orogenic intraplate compressional structures suggests that the respective orogenic wedge and its foreland(s) were mechanically decoupled. The level of mechanical coupling between an orogenic wedge and its foreland is temporally and spatially variable.Mechanical coupling and uncoupling of orogenic wedges and their forelands probably depends on the geometry and frictional shear strength of their common boundary zone. Subduction resistance of the foreland, as well as the buildup of high fluid pressures in subducted sediments, presumably play an important role. Pro-wedge continental crust and mantle-lithosphere can be subducted to depths of 100-150 km at which it can no longer support the weight of the attached oceanic slab and fails. Slab-detachment results in uplift of th...

Evolution of the lithosphere in the area of the Rhine Rift System

“…These stresses induced broad-scale warping and uplift of the European lithosphere, causing the development of a regional erosional unconformity, and, by reactivation of pre-existing faults, inversion of the West-Netherlands and SaarNahe basins. The most distal Paleocene inversion structures are located in the central North Sea, some 1,700 km to the northwest of the contemporaneous Alpine collision front (Ziegler 1990;Ziegler et al 1998Ziegler et al , 2002.…”

“…By contrast, Mesozoic rifting, culminating in the Mid-Jurassic opening of the Alpine Tethys, mid-Cretaceous opening of the Bay of Biscay-Valais Basin (Stampfli et al 1998) and early Eocene opening of the Arctic-North Atlantic (Ziegler 1988), interrupted these cooling trends and caused a renewed destabilisation of the asthenosphere-lithosphere system of shelves flanking these domains (Helvetic, Dauphinois and Atlantic shelves; . During the latest Cretaceous and Palaeocene, the entire ECRIS area was affected by an important pulse of intraplate compression that can be related to early phases of the Alpine and Pyrenean orogenies (Ziegler 1990;Ziegler et al 1995Ziegler et al , 1998Ziegler et al , 2002. At the same time melilite dykes were injected into the Massif Central, Vosges-Black Forest and Bohemian Massif.…”

TOPO-EUROPE: Coupled Deep Earth – Surface Processes in Europe

“…The present-day stress field of the WECEP 6 was successfully modelled by taking Alpine collisional coupling and Atlantic ridge-push forces into account. [7][8][9] Furthermore, acquisition of high-quality tomographic data 10 permitted imaging of the thermal structure of the sub-lithospheric mantle beneath the WECEP, revealing that, in the ECRIS area, low-velocity anomalies occur immediately above the 410 km discontinuity. These are interpreted as mantle plume heads from which secondary 'baby-plumes' intermittently welled up, 4,11 as currently evident beneath the Massif Central 12 and the Rhenish Massif.…”

Stages of development in the Polish Carpathian Foredeep basin

“…The Carpathian Foredeep Basin is a typical slab-loaded fore-arc foreland basin [70] that developed in front of the advancing Carpathians. The arcuate shape of the Carpathians and their foredeep ( Fig.…”