Geology and tectonics of Northwestern South America. The Pacific-Caribbean-Andean Junction / Геология и тектоника северо-западной части Южной Америки. Место соединения Тихого океана, Карибского бассейна и Анд

. Based upon early field studies within the Macarena range and the Roraima tepuis, Augusto Gansser documented the puzzling relationships between the Guiana Shield and the Andean belt, in the process formulating the “Roraima Problem” from a geomorphologic-stratigraphic standpoint. Subsequent studies served to highlight the “problem” within the Macarena uplift, where Cambrian sediments are exposed at approx. 1000 m above sea level whilst Silurian sediments within the Orinoco low are buried at approx. 2300 m depth. The coexistence of vertical tectonics (over 2000  m displacement) and extensional strain systems (Phanerozoic graben-rift fills), with thrust-and-fold belts, may point to concealed wrench structures in subsurface, undetected by geophysical methods. An updated synthesis of the Roraima Problem, using new surface and sub-surface cartographic and structural data, is presented within Chap. 1 of this volume. Redrawn from Gansser A., 1941, Central Macarena, Geological Report Shell No. 100, Appendix 12-16 with enclosures. <...>