Tectonics and paleogeography of the Marajó Basin, northern Brazil

Abstract

The Marajó Basin area presents geologic and geomorphologic features chiefly due to the Mesozoic extension and post-Miocene neotectonics. The extension event with an Early and a Late Cretaceous phases originated four sub-basins that constitutes the Marajó Basin, with a thick continental clastic sequence showing marine influence. NW and NNW normal faults and NE and ENE strike-slip faults controlled the basin geometry. The extension, related to the Equatorial Atlantic opening, propagated into the continent along crustal weakness zones of the Precambrian Tumucumaque, Amapá and Araguaia orogenic belts. The neotectonic event is a strike-slip regime which developed transtensional basins filled in by Upper Tertiary shallow marine (Pirabas Formation) and transitional sequences (Barreiras Group), followed by Quaternary fluvial deposits and transitional sequences derived from the Amazon and Tocantins rivers and the Marajoara estuary. The current landscape has a typical estuarine morphology. The coast morphology presents sea-cliffs on transitional Upper Tertiary sequences, while inwards dominate hills sustained by Mid-Pleistocene lateritic crust, with a flat erosive surface at 70 m. In the eastern Marajó Island several generations of paleochannels associated with fluvial-estuarine sequences are recognized, while a fluvial-marine plain is widespread on its western side.

Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

“…2). The latter basin consists of an assemblage of genetically related taphrogenic sub-basins ( Figs Villegas (1994) and Costa et al (2002).…”

Neotectonics in the northern equatorial Brazilian margin

“…In addition, the several drainage anomalies are commonly related to tectonic influenced streams (e.g., Holmes, 1965;Howard, 1967;Ouchi, 1985;Summerfield, 1991). In combination, the NWeSE and NEeSW main modes, and the secondary EeW mode of the morphostructural lineaments coincide with main fault zone trends documented in other Amazonian areas Costa and Hasuy, 1997;Costa et al, 2002).…”

“…An increasing number of publications has proposed tectonic activity in this region in the Neogene (e.g., Costa and Hasuy, 1997;Costa et al, 2002;Bemerguy et al, 2002;Rossetti, 2006) and Quaternary (Costa et al, 2001;Bezerra, 2003;Miranda et al, 2009;Rossetti, 2010). However, two main problems must be approached: 1. field data must demonstrate tectonic structures in this area (at the moment, the data available derive mostly from analysis of morphostructural lineaments extracted from modern drainage networks); and 2. there has been no discussion on the most likely deformation mechanism.…”

Evolução sedimentar miocênica nos estados do Pará e Maranhão

“…Os processos tectônicos nestas bacias mostraram-se efetivos não só durante o tempo da fragmentação principal, mas permaneceram ativos durante o Cretáceo e Cenozóico (Costa e Hasui, 1997;Costa et al, 1993Costa et al, , 1996Costa et al, , 2002. No Mioceno, destaca-se o desenvolvimento de tectonismo em regime de transcorrência, refletido em falhas normais NW-SE e transcorrentes E-W e NE-SW (Costa et al, 1993(Costa et al, , 1995Hasui, 1990;Costa et al, 1996;Ferreira Jr. et al, 1996), que têm continuidade até o Recente.…”