Alter und Genese des Nicoya-Komplexes, einer ozeanischen Paläokruste (Oberjura bis Eozän) im südlichen Zentralamerika

Abstract

ZusammenfassungDer mehrere Kilometer m~ichtige, im wesentlichen aus ozeanischen Basalten aufgebaute Komplex von Nicoya, der den Sockel der zahlreichen pazifischen Halbinseln von Costa tlica und Panama bildet, wird biostratigraphiseh zum ersten Mal in sechs, altersm~Big sehr verschiedene Teilkomplexe (Subkomplexe) AbstractThe Nicoya Complex, built by thick sequences of mainly oceanic basalts and exposed on the numerous pacific peninsulas of Costa Rica and Panama (Fig. 1), is, for the first time, divided by means of biostratigraphic and facies methods. This classification is not only possible by means of biostratigraphic dating of the overlying sediments but also of occasional inclusions of sedimentary silicious and calcareous exotic blocks within the basaltic sequences. This method shows that the formation of the Nicoya Complex, contrary to the hitherto idea of a uniphase and short development, not only took up very long periods of geological time but was also very discontinuously built. The Nicoya Complex can now be divided into six subeomplexes of different age which, in part, may already be regionally differentiated (Fig. 88). These subeomplexes have to be interpreted as being submarine, abyssal to bathyal sheet flows of mainly tholeiitic basalts up to several hundred meters in thickness. During these effusions of short time duration, the sedimentary cover, in the meantime deposited on the underlying effusiva, was more or less intensively reworked by these processes and deported within the new effusion body

Anatomy of an Evolving Island Arc: Tectonic and Eustatic Control in the South Central American Fore‐Arc Area

“…1990). Discontinuous units of radiolarites found among the basalts have been assigned ages ranging from early Liassic until Santonian (de Wever et al .• 1985;Schmidt-Effing. 1979; H.J.…”

“…from one of these intercalations allowed this unit to be dated as late Campanian. On a regional scale, these brecciated deposits laterally interfinger with pelagic limestones, which yielded both early and late Campanian ages (Schmidt-Effing, 1979;Baumgartner et al, 1984;Astorga, 1988).…”

Ophiolitic Rocks of the Middle America Trench Landward Slope off Guatemala: Deformational Characteristics and Tectonic Significance

“…On the Nicoya Peninsula a Jurassic to Cretaceous basalt-chert sequence outcrops extensively with Tertiary island-arc sedimentary rocks (Schmidt-Effing, 1979;Galli-Olivier, 1979;Kuijpers, 1980;Lundberg and Moore, 1982;Gursky et al, 1982;Azema and Tournon, 1982). The Nicoya sequence is interpreted either as an oceanic plate fragment accreted to the Caribbean Plate or as a mixture of an aseismic ridge and island-arc bodies.…”

The Middle America Trench in the Geological Framework of Central America

“…The Nicoya Peninsula is formed by a volcanic-sedimentary series determined by radiolarian assemblages as Upper Jurassic(?) and Cretaceous (Azéma et al, 1979;Galli, 1979;Schmidt-Effing, 1979). The relation between the Santa Elena peridotites and the Nicoya Complex is unknown.…”