Significance and genetic interpretation of the sequential organization of the aptian-albian lacustrine system of the Araripe basin

SIGNIFICANCE AND GENETIC INTERPRETATION OF THE SEQUENTIAL ORGANIZATION OF THE APTIAN-ALBIAN LACUSTRINE SYSTEM OF THE ARARIPE BASIN

VIRGÍNIO H. NEUMANN ¹ and LLUIS CABRERA ²

¹Departamento de Geologia, UFPE, Cidade Universitária, 50730-540 Recife-PE, Brasil.

²Facultat de Geologia, Universitat de Barcelona, Campus de Pedralbes, 08028, Barcelona.

Presented by ALCIDES N. SIAL

The Aptian-Albian lake system studied here is inserted in the post-rift sedimentary infill of the Araripe basin. Based on surface and subsurface data it was possible to demonstrate that this lacustrine dispositive interacted with one or various fluvio-deltaic environments which contributed with terrigenous materials into the lake. The lacustrine sequence was defined as a interdigitation set within the carbonated and terrigenous bodies. Six main episodes of lacustrine carbonated sedimentation (C1 to C6) were registered in this lacustrine sequence. The successions were grouped in transgressive-regressive sequences of different orders and hierarchies. These successions was developed by minor transgressive-regressive successive pulses (minor frequency sequences). The whole sequence behaved like an expansive lake. The main transgressive pulses considered significant to the sequential subdivision of the lacustrine record, overflowed the depositional area, occupping even major regions in the basin, so that the last lacustrine episodes (immediately before the final evolution of the lacustrine system) reached more extension areas. Each intermmediate order transgressive-regressive sequence occurred with small transgressive-regressive pulses, which produced periods of relative estabilization. The whole association of trangressive-regressive pulses had a duration of aproximately 1 to 3 millions years and was divided into six episodes (C1 to C6) characterized by the main transgression, which had a duration varying from 200,000 to 500,000 years. In conclusion, it was possible to define the hierarchy of the lacustrine sequence which order was the result of a junction of climatic and tectonic factors that controlled the evolution of the Aptian-Albian lacustrine system of the Araripe basin. Further studies, for example, a high resolution analysis of the terrigenous and carbonated lacustrine sequences will permit to advance in a proposal of genetic-sequential analysis according to the characteristics of the lacustrine dispositive that generated it. (May 19, 2000)

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Publication Dates

• Publication in this collection
  05 Jan 2001
• Date of issue
  Dec 2000