The North Karakorum side of the Central Asia geopuzzle

An Italian geological team visited a remote and in part never studied area in the northern Hunza region (Pakistan), which represents the link between the Karakorum and Pamir Ranges. The north Karakorum sequence commences in the Permian with terrigenous sediments, followed by shallow- to deep-marine carbonates deposited on a newly formed passive margin. Deep-water sedimentation continued till the end of the Middle Triassic, when carbonate platform conditions resumed. An episode of deltaic red sandstones with orogenic provenance is interbedded in the Liassic, and it is transgressed by a Middle to ?Upper Jurassic shallow water marine unit. Eventually, all of the sequence was faulted and folded, with weak metamorphic imprint, before fluviatile red polygenic conglomerates sealed the succession,in a spectacular unconformity. The north Karakorum provides an example of a microplate that rifted away from Gondwana in the Permian, reached deep-marine conditions in the Early Triassic, and marginally recorded compressive movements in the Liassic. A subsequent orogenic episode points to a reorganization of the southern Asian margin possibly around middle Cretaceous time. Finally, the north Karakorum was affected by strong fold-thrust deformation and low- to very low-grade metamorphism in the Cainozoic, related to the India-Asia collision.