Pic of the day #7 (Continent-continent collision)

(a) Precollision configuration. Continent A has a passive-margin basin on its east coast, while Continent B has a convergent margin on its west coast
(b) During the initial stage of collision, the passive margin is uplifted, and an unconformity (locally, with karst) develops. Turbidites derived from Continent B soon bury this unconformity (see inset). Normal faults break up the strata of the passive-margin basin, due to stretching. But soon, thrusts begin to develop, transporting the deeper parts of the basin over the shallower parts.


(c) In a mature collision orogen, the subducting slab has broken off, a suture has formed, and metamorphic rocks are uplifted and exhumed in the interior of the orogen.
Pic courtesy: Earth Structure – An Introduction to Structural Geology and Tectonics [Second Edition][W. W. Norton & Company][Ben A. van der Pluijm & Stephen Marshak][2004]

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