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| Titel |
Volcanological aspects of the northwest region of Paraná continental flood basalts (Brazil) |
| VerfasserIn |
F. Braz Machado, E. Reis Viana Rocha-Júnior, L. Soares Marques, A. J. Ranalli Nardy |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 1 ; Nr. 6, no. 1 (2015-02-19), S.227-241 |
| Datensatznummer |
250115399
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| Publikation (Nr.) |
 copernicus.org/se-6-227-2015.pdf |
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| Zusammenfassung |
| There has been little research on volcanological aspects of Paraná
continental flood basalts (PCFBs), and all investigations have mainly been
concentrated on the internal portions of the lava flows. Thus, this study
describes for the first time morphological aspects of lava flows and
structural characteristics caused by lava–sediment interaction in the
northwestern PCFB province (NW-PCFB). Early Cretaceous (134 to 132 Ma) tholeiitic
rocks of the PCFB were emplaced on a large intracratonic Paleozoic
sedimentary basin (Paraná Basin), mainly covering dry eolian sandstones
(Botucatu Formation). As this sedimentary unit is overlain by the basic lava
flows of the PCFB, the interaction of lavas and unconsolidated sediments
resulted in the generation of fluidal peperites. This aspect is significant
because it shows that restricted wet environments should have existed in the
Botucatu desert. The peperite zones of the NW-PCFB are associated with
compound pahoehoe-type (P-type) flows and are always related to the first
volcanic pulses. These flows have dispersed vesicles and sand-filled cracks
in their base and top borders, as well as the presence of interlayered
sandstones with irregular contacts and varied thicknesses. It is remarkable
that, to the best of current knowledge, only in this area of the whole PCFB did the
volcanic activity start with low-Ti basalt flows of Ribeira type (TiO2
< 2.3 wt%), which are scarce in the province. |
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