06 Fakultät Luft- und Raumfahrttechnik und Geodäsie

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Publication Type: search.filters.UBSTyp.BuchbeitragEnd date: 1999

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    Stratigraphic chart of the sedimentary basins of Costa Rica, Central America
    (1994) Sprechmann, Peter; Astorga, Allan; Calvo, Claudio; Fernández, Alberto
    Costa Rican sedimentary rocks deposited since the Campanian are subdivided into supergroups, groups, subgroups, and formations. The Curime, Boruca and Cerece supergroups are unconformity-bounded units. The preexisting number of formations is considerably reduced. The remaining rock units described in this paper are defined by their depositional environment, using differential sedimentologic criteria. The use of sequence stratigraphic terminology is discussed.
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    Der älteste kalkalkaline Inselbogen-Vulkanismus in Costa Rica. Marine Pyroklastika der Formation Loma Chumico (Alb bis Campan)
    (1994) Calvo, Claudio; Bolz, Angela
    In diesem Artikel werden die ältesten vulkanischen Produkte des Costa-Rica-Inselbogens untersucht, die Subduktions-Prozesse am westlichen Rand der Karibischen-Platte in der Unter-Kreide belegen.
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    Depositional sequences and sequence boundaries in fore-arc coastal embay­ments : case histories from Central America
    (1991) Schmidt, Hannelore; Seyfried, Hartmut
    From Oligocene to Recent times a series of tectonically controlled coastal embayments formed on the Pacific fore-arc side of the southern Central American island-arc system. Each of these basins shows characteristic stratal geometries and facies distributions reflecting the complex interaction of changes of sea level, volcaniclastic input, and tectonic activity (subsidence, uplift). Sequential stratigraphic correlations based on sequence analysis and discontinuity surfaces indicate that eustatic sea-level changes control architecture, geometry, and facies distribution of depositional sequences at the level of second-order cycles. Owing to the particular tectonic position, complete sets of systems tracts are seldom developed. Voluminous sediment supply, especially during episodes of strong volcanic activity, may overcompensate transgressions. Strong uplift may annihilate any sedimentary documentation or reduce sequences to a strongly condensed package with random preservation of estuarine or deltaic facies. The bounding uncomformities (sequence boundaries) are traceable on a regional scale and are related at the level of second-order sequence boundaries to tectonic events that repeatedly affected the island arc during the episode in question.
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    Response of deep-water fore-arc systems to sea-level changes, tectonic activity and volcaniclastic input in Central America
    (1991) Winsemann, Jutta; Seyfried, Hartmut
    The incipient island-arc system of southern Central America (Cretaceous - early Oligocene) is characterized by thick turbidite systems, which mainly filled inner fore-arc troughs. Outcrop data show four second-order depositional sequences in the deep-water sediments. The formation of these depositional sequences is strongly related to the morphotectonic evolution of the island-arc system. Each depositional sequence reflects the complex interaction between global sea-level fluctuations, sediment supply and tectonic activity. Strong marginal uplift and high volcaniclastic sediment supply during early to late Paleocene and late Eocene times caused the formation of coarse-grained channel-lobe systems. During late Paleocene and mid-Eocene times, fine-grained, thin-bedded turbidite systems were deposited, owing to regional subsidence and a decrease in volcanic supply. Uplift and subsidence of sediment-source areas acted as major controls on deposition of basinal cycles.
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    Anatomy of an evolving island arc : tectonic and eustatic control in the south Central American fore-arc area
    (1991) Seyfried, Hartmut; Astorga, Allan; Ammann, Hubert; Calvo, Claudio; Kolb, Wolfgang; Schmidt, Hannelore; Winsemann, Jutta
    The southern part of the Central American isthmus is the product of an island arc. It evolved initially as a ridge of primitive island-arc tholeiites at a collision zone between the Farallon plate and proto-Caribbean crust (Albian-Santonian). During the Campanian, a major tectonic event (most probably subduction reversal) caused décollement of different units of the former plate margin. The resulting structural high was covered by a carbonate platform. From Maastrichtian to Eocenc times continuous subduction produced a stable morphotectonic configuration (trench-slope-outer-arc-fore-arccalcalkaline-arc). Fore-arc sedimentation was controlled by volcaniclastic input and tectonic activity along the outer arc's inner margin. Eustatic control is essentially recognized through lowstand signals such as extensive turbidite sand lobes. Steady accretionary uplift of the outer arc gradually closed the bypasses between forc-arc and trench slope. Eustatic control is verified by lowstand signals (sands) on the trench slope and highstand signals on the outer arc (carbonate ramps). During the Oligocene another major tectonic event affected the entire system: accretion ceased, segments decoupled, and regional compression resulted in general uplift and erosion. From latest Oligocene to Pliocene times, three episodes of tilting created a series of fault-angle depressions. Subsidence varies enormously among these basins. but sedimentation is largely shallow marine. Facies architecture reflects complex interactions between tectonic processes, changes in volcaniclastic sediment supply, and eustasy. Subsequently. very strong explosive volcanic activity resulted in excessive sediment input that overfilled most basins. The history of the island arc shows that tectonic processes largely controlled composition, distribution and geometry of the major sedimentary units. Eustatic signals do indeed occur when they are expected, but may be considered as an overprint rather than a dominating factor.