Abstract
The Pocos de Caldas Plateau is formed by the alkaline intrusion of Pocos de Caldas and surrounding metamorphic basement. It is characterized as a remnant of the South American Planation Surface resulted from erosional events from Late Cretaceous-Paleogene transition. Pocos de Caldas Alkaline Massif (PCAM) was formed during alkaline volcanism event from the Late Cretaceous. It is located on the west side of the Mantiqueira Mountain Range, characterized by alkaline rocks and topography reaches over 1700 m high. A major feature of denudation is the development of the “circular drainage”, a particular feature of some caldera and other circular or concentric structural features. Recent tectonic movements may critically affect regional geomorphology by influencing river patterns and orientations. The morphometric analysis shows that some rivers are controlled by reactivated faults, however, in some regions the lithology has major influence in the rivers development.
Highlights
The southeast Brazilian passive margin records a long history of tectonic magmatism events since the Late Jurassic
This level is supposed to have been formed before the breakup of the Gondwana continent according with [9], this level was formed after the Poços de Caldas Alkaline Massif (PCAM) intrusion, which means they cannot be older than 80 Ma
The results show that most of the rivers are controlled by the intense pattern of NW-SE, NE-SW e NNE-SSW trending faults that can be seen in the longitudinal profile of the main rivers
Summary
Those events were consequence of the South Atlantic Ocean [1] [2]. After the rifting process has ceased, an epeirogenic uplift of the continental crust has started in response to the drifting of the South American Platform over a thermal anomaly that accompanied an intense alkaline and basaltic magmatism [4]. This alkaline volcanism from the Late Cretaceous generates a very particular structure on the Brazilian southeast named Poços de Caldas Alkaline Massif (PCAM). The Poços de Caldas massif is mainly constituted by subvolcanicphonolites (tinguaites), nephelinesyenites (NeS), and mostly altered volcanic phonolites, in part enclosing the overlying eolian Botucatu sandstones and some Serra Geraldiabases [7] [8]
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