Numerical modelling of Quaternary terrace staircase formation in the Ebro foreland basin,southern Pyrenees,NE Iberia          下载免费PDF全文

Kurt Martin Stange  Ronald T. Van Balen  Daniel Garcia‐Castellanos  Sierd Cloetingh 《Basin Research》2016,28(1):124-146

The southern foreland basin of the Pyrenees (Ebro basin) is an exorheic drainage basin since Late Miocene times. Remnants of an early exorheic Ebro drainage system are not preserved, but morphology provides evidence for the Pliocene–Quaternary drainage development. The incision history of the Ebro system is denoted by (i) extensive, low gradient pedimentation surfaces which are associated with the denudation of the southern Pyrenean piedmont around the Pliocene–Quaternary transition and (ii) deeply entrenched Quaternary river valleys. Presumably since the Middle Pleistocene fluvial incision intensified involving the formation of extensive terrace staircase in the Ebro basin. Terrace exposure dating in major Ebro tributary rivers indicates climate‐triggered terrace formation in response to glacial–interglacial climate and glacier fluctuations in the Pyrenean headwaters. The overall (semi)parallel longitudinal terrace profiles argue for progressive base level lowering for the whole Ebro drainage network. The landscape evolution model, TISC, is used to evaluate climatic, tectonic and base level scenarios for terrace staircase formation in the Ebro drainage system. Model simulations are compared with morpho‐climatic, tectonic and chronologic data. Results show that climatic fluctuations cause terrace formation, but the incision magnitudes and convergent terrace profiles predicted by this climate model scenario are not consistent with the (semi)parallel terraces in the Ebro basin. A model including previous (late Pliocene) uplift of the lower Ebro basin results in rapid base‐level lowering and erosion along the drainage network, small late stage incision magnitudes and terrace convergence, which are not in agreement with observations. Instead, continuous Quaternary uplift of both the Pyrenees and the Ebro foreland basin triggers (semi)parallel terrace staircase formation in southern Pyrenean tributary rivers in consistency with the observed longitudinal terrace profiles and Middle–Late Pleistocene incision magnitudes. Forward model simulations indicate that the present Ebro drainage system is actively incising, providing further evidence for uplift.  相似文献   

The relationship between the deep structure and quaternary tectonics of the pamir and Tien-Shan     

V.N. Krestnikov  I.L. Nersesov  D.V. Stange 《Tectonophysics》1984,104(1-2)

The Quaternary period in the Pamir and Tien-Shan is marked by a sharp increase in the intensity of uplift which followed a short tectonically calm period in the late Pliocene and the early Pleistocene. Rates of the upward movement increased from the early Pleistocene to Holocene. The structural pattern of the region was formed throughout the whole neotectonic stage but the present shape is mainly the result of the Quaternary movements. A number of large uplifts and relative depressions can be identified in the Tien-Shan and Pamir. Only some of the greatest depressions were subject to absolute downwarping in their central parts during the Quaternary time. Numerous new data on the thickness of the earth's crust of Central Asia obtained in the past few years have allowed construction of a new relief map of the Mohorovičić discontinuity in the Tien-Shan and Pamir and of the discontinuity in relationship to the character of the Quaternary tectonic movements. As a result, correspondences relating to the development of the earth's crust were established and a suggestion was made as to the current rejuvenation of the structural pattern, with both an anti-Tien-Shan and a meridional direction dominating in the Pamir. The comparison of the development of the earth's crust as a whole with the lateral heterogeneities of the upper mantle confirmed the assumption about the current rejuvenation. At the same time it made evident once again that there are significant differences in the deep processes taking place in the Pamir and Tien-Shan. Combining analyses of both the subsurface and the surface development in this part of Asia provided a better view of the characteristics of the deep fault zones. This has allowed the authors to outline the latent ruptures and establish individual blocks of the earth's crust that show different structure and development.  相似文献