Re-interpretation of a Lower–Middle Cambrian West Gondwanan ramp depositional system: a case study from the Cantabrian Zone (NW Spain) |
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Authors: | Thomas Wotte |
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Institution: | 1.Geologisch-Pal?ontologisches Institut,Westf?lische Wilhelms-Universit?t Münster,Münster,Germany |
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Abstract: | Detailed litho- and biofacies investigations of the Lower–Middle Cambrian carbonate Láncara Formation resulted in its subdivision
into nine lithofacies types: (1) claystone, (2) recrystallized mudstone, (3) laminated mudstone with laminoid-fenestral fabrics,
(4) stromatolite, (5) laminated aggregate grainstone, (6) non-laminated aggregate grainstone, (7) oolitic-bioclastic floatstone,
(8) echinodermal packstone, and (9) bioclastic grainstone. The thicknesses of lithofacies 1–7 (lower member of the Láncara
Formation) decrease from south to north. Lithofacies types 8–9 (upper member of the Láncara Formation) are characterized by
similar thicknesses and low facies and faunal gradients and are thus indicative of deposition on a carbonate ramp. From palaeoecological,
palaeo(bio)geographical, palaeomagnetic, and tectonic considerations, the depositional environment of the Láncara Formation
is re-interpreted as an eastward/north-eastward sloping, low morphology carbonate ramp. The Cantabrian Zone, with a primary
lateral extension of about 300 km, is further construed to be an element of a widespread and connected, discontinuous drowned
Perigondwanan depositional system. |
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Keywords: | Lower– Middle Cambrian Carbonate ramp Spain Láncara Formation Microfacies Palaeoenvironment Palaeoecology |
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