A lost carbonate platform deciphered from clasts embedded in flysch: Štramberk-type limestones, Polish Outer Carpathians

Exotic clasts, debris flow deposits and their significance for reconstruction of the Istebna Formation (Late Cretaceous – Paleocene, Silesian Basin, Outer Carpathians)

Geologica Carpathica ◽

10.1515/geoca-2017-0037 ◽

2017 ◽

Vol 68 (6) ◽

pp. 562-582 ◽

Cited By ~ 3

Author(s):

Piotr Strzeboński ◽

Justyna Kowal-Kasprzyk ◽

Barbara Olszewska

Keyword(s):

Mass Transport ◽

Carbonate Platform ◽

Sedimentary Cover ◽

Source Area ◽

Transport Processes ◽

Coarse Grained ◽

Tectonic Activity ◽

Depositional System ◽

Outer Carpathians ◽

Mass Transport Deposits

AbstractThe different types of calcareous exotic clasts (fragments of pre-existing rocks), embedded in the Paleocene siliciclastic deposits of the Istebna Formation from the Beskid Mały Mountains (Silesian Unit, Western Outer Carpathians), were studied and differentiated through microfacies-biostratigraphical analysis. Calcareous exotics of the Oxfordian- Kimmeridgian age prevail, representing a type of sedimentation comparable to that one documented for the northern Tethyan margin. The Tithonian exotic clasts (Štramberk-type limestones), which are much less common, were formed on a carbonate platform and related slope. The sedimentary paleotransport directions indicate the Silesian Ridge as a main source area for all exotics, which were emplaced in the depositional setting of the flysch deposits. The exotics constitute a relatively rare local component of some debrites. Proceedings of the sedimentological facies analysis indicate that these mass transport deposits were accumulated en-masse by debris flows in a deep-water depositional system in the form of a slope apron. Exotics prove that clasts of the crystalline basement and, less common, fragments of the sedimentary cover, originated from long-lasting tectonic activity and intense uplift of the source area. Mass transport processes and mass accumulation of significant amounts of the coarse-grained detrital material in the south facial zone of the Silesian Basin during the Early Paleogene was due to reactivation of the Silesian Ridge and its increased denudation. Relative regression and erosion of the emerged older flysch deposits were also forced by this uplift. These processes were connected with the renewed diastrophic activity in the Alpine Tethys.

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Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

Journal of Paleontology ◽

10.1017/s0022336000058819 ◽

1988 ◽

Vol 62 (01) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Ronald E. Martin

Keyword(s):

Deep Water ◽

Benthic Foraminifera ◽

Carbonate Platform ◽

Sedimentary Facies ◽

Depositional Environments ◽

Near Surface ◽

Sediment Gravity Flows ◽

Gravity Flows ◽

Platform Margin ◽

Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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