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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Paleotemperatures and paleofluids recorded in fluid inclusions from calcite veins from the northern flank of the Ponta Grossa dyke swarm: Implications for hydrocarbon generation and migration in the Parana Basin

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Author(s):
Nomura, S. F. [1] ; Sawakuchi, A. O. [1] ; Bello, R. M. S. [1] ; Mendez-Duque, J. [1] ; Fuzikawa, K. [2] ; Giannini, P. C. F. [1] ; Dantas, M. S. S. [3]
Total Authors: 7
Affiliation:
[1] Univ Sao Paulo, Inst Geociencias, Dept Geol Sedimentar & Ambiental, BR-05508080 Sao Paulo - Brazil
[2] Comissao Nacl Energia Nucl, Ctr Desenvolvimento Tecnol Nucl, Serv Tecnol Mineral, BR-31270901 Belo Horizonte, MG - Brazil
[3] Univ Fed Minas Gerais, Inst Ciencias Exatas, Dept Fis, BR-31270000 Belo Horizonte, MG - Brazil
Total Affiliations: 3
Document type: Journal article
Source: MARINE AND PETROLEUM GEOLOGY; v. 52, p. 107-124, APR 2014.
Web of Science Citations: 4
Abstract

The Parana Basin, southern Brazil, has an atypical thermal and fluid history due to the occurrence of an episodic continental flood volcanism during the Early Cretaceous. So far, there are few data about the influence of this volcanic event on the paleotemperatures and paleofluids of the Parana Basin sedimentary rocks. The Teresina Formation in the northern flank of the Ponta Grossa dyke swarm hosts high concentration of subsurface igneous rock bodies (sills and dykes), besides its covering by a hundreds meter thick volcanic rock cap. In this study, we used fluid inclusion analysis performed in horizontal and vertical calcite veins from the Teresina Formation and from a Late Cretaceous basic dyke to estimate paleotemperatures and to characterize the composition of diagenetic paleofluids. Homogenization temperatures of requilibrated fluid inclusions show that the Teresina Formation reached temperatures above 200 degrees C. Horizontal parallel bedding calcite veins from the Teresina Formation record low to high salinity (2-26 wt.% NaCl eq.) aqueous paleofluids. The prevalence of high salinity fluid inclusions associated with light hydrocarbon fluid inclusions indicates deep buried fluids. Fluid inclusions in vertical calcite vein from basic dyke comprise only low salinity aqueous fluids (0-3 wt.% eq.NaCl) interpreted as dominated by meteoric water. The recorded paleotemperatures are attributed to the heating by the Parana volcanic event during the Early Cretaceous, with the thermal effect of the volcanic rock cap surpassing the effect of nearby sills and dykes. Estimated paleotemperatures higher than 200 C would allow the generation of light liquid and gaseous hydrocarbons. Overpressured compartments in the Teresina Formation allowed the expulsion of buried pore fluids (high salinity aqueous fluids and hydrocarbons) to fracture systems, where they mixed with meteoric water. The input of meteoric water through fracture systems connected with the surface favored hydrocarbons degradation in the early stages of source rock maturation during the Early Cretaceous. (C) 2014 Elsevier Ltd. All rights reserved. (AU)