The Capo Malfatano Metaconglomerates in the Early Cambrian of SW Sardinia, Italy: key level for a new stratigraphic setting and evidence of Cadomian tectonics

COSTAMAGNA, LUCA GIACOMO

2015-01-01

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Abstract

In the Capo Malfatano area (Southern Sardinia) an epimetamorphic succession with undefined boundaries and age named informally “Bithia Fm” crops out, which is here referred to the Early Cambrian by the new finding of Archaeocyatha specimens. In the “Bithia Fm”, formed mainly by metasiliciclastics with rare metavolcanics and metacarbonates, a coarse-grained horizon, the Capo Malfatano Metaconglomerates is contained. Its sedimentary features and tectonic meaning have been investigated. This horizon rests unconformably on the substratum and represents a key level that can be traced in the investigated area. The Capo Malfatano Metaconglomerates divide the “Bithia Fm” of earlier authors into two different parts. The lower part has been designated as the real Early Cambrian Bithia Fm, while the upper part has been referred to the Early Cambrian Matoppa Fm. This starts unconformably with the metaconglomerate horizon. The depositional environment of the Capo Malfatano Metaconglomerates is referred to as a continental fluvial setting. These metaconglomerates and the orogenic context of the lower Bithia Fm suggest a Cadomian tectonics.