Cretaceous frontal thrusts of the Verkhoyansk fold belt, eastern Siberia

Abstract

Cretaceous thrust structures are found along the front of the Verkhoyansk miogeoclinal fold belt along the eastern boundary of the Siberian platform in northeast Asia. The Verkhoyansk thrust front is subdivided into a number of segments, each of which has its own thrust system geometry. Balanced cross sections have been constructed for each segment on the basis of the structural study of surface geology and available seismic and drilling data. Distinctions between the segments are also expressed in gravity anomalies and modern topography. Analysis of vitrinite reflectance shows that folding of the Verkhoyansk thrust front was initiated during sedimentation as early as in the Late Jurassic. This period marks the beginning of the collision between the Siberian continent and the Kolyma‐Omolon superterrane, now located 500 km to the east of the Verkhoyansk thrust front. Deformation of the thrust front ended by the late Late Cretaceous; erosion of the frontal anticlines began in the early Late Cretaceous. The frontal thrust structures formed in the Late Cretaceous were rejuvenated during a middle to late Pleistocene reactivation, which produced the modern mountain topography. The least amount of erosion of the Verkhoyansk thrust front, 840 m, is observed in its central part, in the Kuranakh segment. To the north and south the erosion increases to 1500 m and 2100 m, respectively. The general configuration of the Verkhoyansk fold belt and its frontal structures are defined by the geometry of Devonian rift‐related structures on the eastern Siberian platform and the principal direction, approximately east–west, of Late Cretaceous compressional stresses.