Ignimbrites of the Pliocene Bagaces Formation near Cañas (Guanacaste, Costa Rica).

Semm, Wolf and Alvarado, Guillermo E. (2007) Ignimbrites of the Pliocene Bagaces Formation near Cañas (Guanacaste, Costa Rica). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 246 (3). pp. 313-323. DOI 10.1127/0077-7749/2007/0246-0313.

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Abstract

By this study, four units within the so far mostly undivided Bagaces Formation - a major ignimbrite unit of the Plio- to Pleistocene magmatic succession in northern Costa Rica - were identified and their ignimbrite sequences stratigraphically distinguished. The basal welded Montenegro ignimbrite of mid-Pliocene age forms the lowermost stratigraphic member. It is followed by three non-welded ignimbrite units of Upper Pliocene age, Sandillal (4.1-4.15 ± 0.02 Ma) and Cañas (2.06 ± 0.02 Ma) and the locally exposed Río Tenorio ignimbrite (estimated age 2 Ma). The ignimbrite units of the Bagaces Formation show decreasing thicknesses from NE to SW. For the non-welded Sandillal and Cañas units, distal lobes could be defined. Lateral pumice and lithics size distribution, as well as isopach data indicate a paleotopographical control for the deposition of the ignimbrites and allowed defining the source area of the ignimbrites. Ar-Ar-ages and compositions analysis of the pyroclastic units refer to the eruptive evolution of the Neogene volcanic arc.

Document Type: Article
Keywords: Volcanology; Bagaces Formatio; ignimbrites
Research affiliation: OceanRep > SFB 574 > C4
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
OceanRep > SFB 574
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1127/0077-7749/2007/0246-0313
ISSN: 0077-7749
Contribution Number:
ProjectNumber
SFB 574128
Expeditions/Models/Experiments:
Date Deposited: 13 Jul 2010 10:04
Last Modified: 23 Sep 2019 17:39
URI: http://oceanrep.geomar.de/id/eprint/8619

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