Abstract

New 1:5,000 geological mapping of ?Middle-Late Triassic successions in the metamorphic core of the Apuan Alps has led to improved knowledge of the stratigraphy and geodynamic setting of the Northern Apennines. The Verrucano ss. mainly consists of massive and amalgamated beds of polymictic, often matrix-supported meta-conglomerates with minor quartzitic and meta-pelitic intercalations. Their "immature" compositional and textural features (e.g. the local abundant content in lithics and feldspar components) distinguish the Verrucano of the Apuan Alps from the classic "anagenites" (a local name for the Triassic quartz-pebble metaconglomerates] of the fluvial Verruca Fm. In this paper, the Apuan Verrucano is ascribed mainly to deposition in alluvial fans and/or to infilling of narrow valleys cut into morphological-structural highs of the Paleozoic basement, probably bounded by active faults. The overlying Carnian Vinca Fm. is a marine carbonate-siliciclastic unit attributed to a neritic-littoral environment dominated by tides and along-coast currents. Nearby deltaic systems fed the carbonate platform with variable amounts of siliciclastic sediments, probably produced by the erosion of residual basement highs. During the deposition of the Vinca Fm. repeated dismantling of the already formed carbonate platform also took place, as testified by intra-formational breccias, probably related to sea level variations on a weakly subsiding margin and/or to positive tectonic pulses. The data are used in a tentative paleogeographic reconstruction of the Middle-Late Triassic landscape.

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