CONSTRAINTS ON THE EVOLUTION AND THERMAL HISTORY OF THE CONTINENTAL PLATFORM OF SOUTHEAST BRAZIL, SÃO PAULO STATE, USING APATITE FISSION TRACK ANALYSIS (AFTA)

SANDRO GUEDES DE OLIVEIRA, PETER CHRISTIAN HACKSPACHER, JÚLIO CÉSAR HADLER NETO, PEDRO JOSÉ IUNES, SÉRGIO ROBERTO DE PAULO, LUIZ FELIPE BRANDINE RIBEIRO, CARLOS ALBERTO TELLO SÁENZ

Resumo


Phanerozoic tectonic events in southeastern Brazil played an important role in the structuring of the South American Platform and its continental margin. During the Mesozoic the Pangea supercontinent was affected by rifting and continental separation processes resulting in the formation of a coastal margin basin associated with the uplift of the continental margin. These tectonic and epeirogenic processes were responsible for many of the present-day tectonic features and geomorphological characteristics of the region. Apatite Fission Track Analysis (AFTA) has been used for the determination of thermal histories and cooling ages, together with geological and geomorphological information, allowing to qualify and to quantify the timing of epeirogenic and tectonic processes. An AFTA study of a northwest-southeast profile, between the Mantiqueira Mountain Range (MMR) and the Atlantic Ocean, shows well-defined tectonic and thermal reworking. The thermal histories, of the different studied regions, show a similar uplift/denudation signature with a strong, tectonic controlled, uplift process. The thermal histories show that uplift started at ~ 121 Ma in the Upper MMR, at ~ 62 Ma for the lower MMR and ~80 Ma for the Serra do Mar Mountain Range (SMMR). The Continental Platform of southeastern Brazil experienced a series of vertical and horizontal movements between the Cretaceous and the present day. A sequence of northeast-southeast blocks were uplifted, starting at different times but following similar patterns of evolution.

Palavras-chave


AFTA; South American Platform; Cretaceous.

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