Role of pre-rift rheology in kinematics of extensional basin formation: constraints from thermomechanical models of Mediterranean and intracratonic basins

Abstract

The role of pre-rift rheology on the kinematics of extensional basin formation is examined. Constraints obtained on the effective elastic thickness and level of necking, inferred from forward modelling of a number of Alpine/Mediterranean basins (including the Gulf of Lion margin, the Valencia Trough, the Tyrrhenian Sea and the Pannonian Basin), are interpreted in terms of the pre-rift rheology of the lithosphere underlying these basins. The Gulf of Lion/Tyrrhenian Sea basins and the Pannonian Basin appear to be end-members in terms of the inferred depth levels of necking. The models support the existence of spatial variations in crustal and lithospheric strength, as inferred from previous rheological modelling for other segments of the European lithosphere, and provide constraints on the ratio of crustal and subcrustal strength during extension. The results of these studies are compared with predictions on the kinematics of extension for a number of intracratonic basins, including the Black Sea basins, the Transantar, ctic Mountains/Ross Sea and Saudi Arabian Red Sea margins, and the Baikal and East African rifts. The kinematics of extension appears to be largely controlled by the (transient) thermal regime of the pre-rift lithosphere and the crustal thickness distribution. These usually result from orogenic processes operating on the lithosphere before extensional basin formation. Predictions are made for the level of external forces required to initiate rifting in intracratonic and Alpine/ Mediterranean settings. The models also shed light on the relative parts played by far-field versus near-field stresses and inferred variations in strain rate during the evolution of these basins.

Evolution of rifted continental margins: The case of the Gulf of Lions (Western Mediterranean Basin)

“…In a second stage (Fig. 10B) thermo-mechanical models and give mechanical constraints on the complex interplay between 450 subduction and roll-back processes in extensional basin formation (Cloetingh et al, 1995). 451 Different mechanisms have been proposed to explain rift flank uplift on extensional margins 452 landward of the hinge zone, including thermal processes (Royden and Keen, 1980;Keen, 453 1985;Steckler, 1985;Buck, 1986) and flexural isostatic rebound in response to mechanical 454 unloading of the lithosphere during extension (Watts, 1982;Weissel and Karner, 1989 …”

Stress-induced late-stage subsidence anomalies in the Pannonian basin

“…The level of necking can be connected with the zone of maximum lithospheric strength , or alternatively with the depth of intra-lithosphere detachment ( Van der Beek et al, 1994). The basin formation processes in the Pannonian basin would by its association with thick pre-rift Alpine crust and a high-temperature regime qualify for a low-strength lithosphere and a level of necking at shallow depth (see Cloetingh et al, 1995 for discussion). The basin formation processes operating in the Pannonian basin have been modelled by us (Van Balen and Cloetingh, 1995;Van Balen et al, 1996) using constraints from a large dataset of wells and seismic profiles acquired by petroleum exploration in the basin support a necking depth level between 5 and 10 km.…”

Extensional basins of the former Soviet Union — structure, basin formation mechanisms and subsidence history

“…The rifts in the FSU, located on lithosphere with different thermo-tectonic ages, show a clear relationship between the style of near-surface tectonics and the bulk rheological properties of the deeper lithosphere (for a general discussion see Cloetingh et al, 1995). The present-day Baikal rift and the Devonian rifts of the East European and Siberian platforms, such as the Vilyuy rift system, are examples of rifting occurring in thick cold lithosphere (see Figs.…”