Abstract

Refinement of the supercontinental reconstruction for the latest Precambrian that places the Labrador-Greenland promontory of Laurentia within the Arica embayment along the margin of the Gondwana craton juxtaposes the Rockall microcontinent and northwestern British Isles with the continental margin of Peru. The conjugate cratonic margin to the northwest Caledonian foreland, the Hebridean shield, may have been Amazonia. Possible South American correlatives of the Precambrian Moinian and Dalradian complexes of the Scottish Highlands can be identified in the reconstruction; notably, there are possible equivalents of the "older granites" within the Moinian and of Dalradian glacial deposits. Therefore, the well-studied Precambrian rocks of the Scottish Highlands provide critical tests for the suggested reconstruction. The latest Precambrian setting of the Arequipa massif with respect to the Gondwana craton margin and the Paleozoic intracratonic basin of Peru-Bolivia bears a striking similarity to the early Mesozoic setting of the Rockall Plateau and northwestern British Isles with respect to the European continental margin and the North Sea-Western Approaches graben system. In each case rifting appears to have been controlled by the youngest, and presumably weakest, lithosphere, but the extremity of the Labrador-Scotland-Greenland promontory was detached during final continental separation in Vendian to earliest Cambrian time to form the Arequipa massif and in Jurassic time to form the Hebridean shield. The promontory may have played an important tectonic role through at least 1 b.y. of Earth history including influence on the development of the Andean Cordillera. Features of this type likely have played a major role in the development of orogenic belts of all ages.

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