Andjic, G.

Bandini, A.

Baumgartner, P. O.

Baumgartner-Mora, C.

Buchs, David M.

Flores, K.

English

OceanRep

Geophysical Research AbstractsVol. 14, EGU2012-1933, 2012EGU General Assembly 2012© Author(s) 2012Oceanic terranes of S-Central America – 200 Million years of accretionhistory recorded on the W-edge of the Caribbean Plate.P. O. Baumgartner (1), K. Flores (1,2), A. Bandini (1,3), D. Buchs (1,4), G. Andjic (1), and C. Baumgartner-Mora(1)(1) University of Lausanne, Switzerland (Peter.Baumgartner@unil.ch), (2) American Museum of Natural History, New York,USA, (3) University of Western Australia, Crawley, Australia, (4) IFM-GEOMAR, Kiel, GermanyThe W-edge of the Caribbean Plate is characterized by two major basement domains, separated today by a SW-NEtrending diffuse fault zone located SE of the Nicoya Peninsula (Costa Rica) and possibly connecting with the HessEscarpment. To the NW, in the area originally called “Chortis Block”, oceanic island/arc basements range in agefrom Late Triassic to Early Cretaceous and form a complicated puzzle of geodynamic units. To the SE of this faultline, no age older than Turonian-Santonian (90-85 Ma) is known. This area only represents the trailing edge of theCaribbean Large Igensous Procince (CLIP).The Mesquito Composite Oceanic Terrane (MCOT) comprises the southern half of the “Chortis Block”, classicallyconsidered as a continental fragment of N-America. The MCOT is defined by isolated outcrops of ultramafic, maficoceanic/arc rocks, and radiolarites of Late Triassic, Jurassic and Early Cretaceous age: Rhaetian (latest Triassic)radiolarites found in the El Castillo Mélange (S-MCOT: S-Nicaragua/N- Costa Rica). They are associated withblocks of OIB-metabasalts. These rocks document the presence of a Late Triassic oceanic basement that must havebeen the substrate of the 174 -177 Ma old (Early/Middle Jurassic) Petit-Spot-like alkaline volcanics that intrudedEarly Jurassic radiolarites. These rocks form tectonic slivers in the middle Cretaceous Santa Rosa AccretionaryComplex (relative autochthonous of the Santa Elena ultramafic unit, N-Costa Rica).The oldest rocks of the Nicoya Complex s. str. (NW-Nicoya Peninsula, Costa Rica) are Bajocian (Middle Jurassic)radiolarites, that occur as blocks magmatically engulfed in plateau-type basalts and intrusives that range in agethoughout the pre-Campanian Cretaceous (130-83 Ma).Middle and Late Jurassic metaradiolarites occur as blocks in the Siuna Serpentinite Médange (NE-Nicaragua),along with High-p, arc-related mafics. We envision an oceanic arc that collided in the latest Jurassic with the AguaFria arc system (Chortis Block s. str.), and became exhumed again by the earliest Cretaceous (139 Ma phengiteage).A pre-Albian basaltic plateau-like basement is suspected but yet undated in the Matambú Terrane (Central NicoyaPeninsula). It is overlain by the Albian Loma Chumico Formation.A pre-Turonian basement hosting the 90 Ma old Tortugal Picrites and alkaline baselts characterizes the ManzanilloTerrane ( around the Nicoya Gulf, Costa Rica). The overlying Coniacian-Santonian to early Campanian BerrugateFormation represents the first Cretaceous evolved arc activity. It must be located on the edge of the MCOT, sincethe CLIP is still forming at that time.To the SE of the S-Nicoya fault zone, Turonian-Santonian (∼90-85 Ma) oceanic plateaus represent outcrops of theCLIP. These include parts of Herradura (Costa Rica) and the Azuero Plateau (Coiba, Sona and Azuero, Panama).Late Campanian to Paleocene arcs rest on the CLIP: The Golfito Complex (Costa Rica) and the Azuero Arc(Panama), possibly also the San Blas Complex (Panama) and the Serrania de Baudo (W-Colombia).Late Cretaceous to Eocene plateau/seamount basalts and oceanic sediments became accreted during the EarlyTertiary: The Tulin Group (Herradura), Quepos, The Osa Igneous Complex, Burica, the Osa Mélange (CostaRica/Panama), and the Azuero Accretionary Complex (Panama).

Oceanic terranes of S-Central America - 200 Million years of accretion history recorded on the W-edge of the Caribbean Plate

Abstract

Similar works

Full text

Available Versions

OceanRep