TECTONISM IN NORTH AND SOUTH AMERICA DURING UPPER MESOZOIC: FAR FROM RHETORIC, CLOSER TO REALITY

Jura-Triassic rocks are present in the ancient eastern continental margin of North America in at least twenty different basins described by several American geologists since the 19th century, where sedimentary rocks intercalated with basic volcanic rocks as Newark Supergroup is comparable to sequences at the western margin of South American continent during those geological periods.

It is important to give and support precedent and, recent research presented at the last annual meeting in Vancouver GSA, providing a slightly more scientific tectonic analysis.

Analyzing North American geological maps in diverse areas and visiting some of them, where volcanic and clastic sedimentary rocks of Mesozoic are well represented, it is possible to confirm that strike of rocks exposed between New Haven, CT (South) to Keene, NH (North) is NE similar to the South margin.

Regionally, the strata inclined eastward into the Hartford basin (CT), in contrast to dip to the West in Newark basin (NJ). The eastern margin of the basin of Hartford formed by a large fault while the western part pre-existing rocks affected by major geological movements such as Ramapo Fault, both faults with strike NE apparently had formed an enormous anticline.

Perhaps, all layers are initially deposited with direction from North to South and later, the strike changed to Northeastern as a result of intense and immense faulting near the North Pole. A rotational movement of North America moved it down to the SW. This observation has a logic comparing and contrasting the well-known Transformation Fault named San Andres in California, which could be horizontal initially and now moved to the SW as well. Actually it has Northwestern strike.

On the other, in South America the fault system affecting the Triassic Jurassic rock has NE strike. However, the lower Mesozoic affected by uplift of Precambrian igneous and metamorphic rocks at the North part next to Santa Marta Ridge in Colombia, similar to the Denver basin in Colorado. the Laramie orogeny affected to the Morrison Formation .