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Research Articles: Provenance Analysis |
1 Department of Earth and Geoenvironmental Sciences, University of Bologna, 40126 Bologna, Italy; cavazza{at}geomin.unibo.it
2 Department of Earth and Space Sciences, University of California, Los Angeles, California 90095-1567, U.S.A.
During OligoceneNeogene time, the CalabriaPeloritani terrane (CPT), a small block of continental lithosphere, rifted from the southern margin of the Eurasian continent and drifted southeastward to collide with the African continent. Along the leading edge of the CPT, a late Oligocene to Quaternary, mostly siliciclastic succession (> 2,000 meters thick) was deposited in the Ionian forearc basin. The detritus forming the succession was derived directly from the erosion of the nearby CPT, composed of Hercynian plutons intruding metasedimentary host rocks. Contrary to most modern and ancient forearc basins, penecontemporaneous volcanic detritus is virtually absent; this results from rift-related topographic barriers which separated the forearc basin from the associated volcanic arc.
In spite of an overall quartzofeldspathic, continental-block provenance, the analysis of a large sandstone and conglomerate petrological dataset (228 samples) points to three discrete detrital inputs of aphanitic lithic fragments in (i) late Oligoceneearly Miocene, (ii) late Messinian, and (iii) Quaternary times. These petrological variations can be linked to independently determined tectonic events in the western Mediterranean, which likely modified the lithologic composition of the sediment source terranes. Input (i) documents the progressive, widespread unroofing of the continental basement of the southern European margin, when northwestward subduction of the remnants of the Ligurian ocean began. Input (ii) is related to widespread intra-Messinian tectonism possibly due to out-of-sequence thrusting induced by isostatic readjustments of the perimediterranean orogenic wedges following the Messinian drawdown. Input (iii) reflects the rapid vertical uplift experienced by the CPT since mid-Pleistocene time, possibly the result of slab detachment along the Ionian subduction zone.
This study indicates that detailed statistical analysis of the detrital modes of ancient terrigenous deposits can be used to identify the tectonic events affecting somewhat petrologically monotonous sediment source areas within small lithospheric terranes.
This article has been cited by other articles:
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M. Barone, R. Dominici, F. Muto, and S. Critelli Detrital Modes in a Late Miocene Wedge-Top Basin, Northeastern Calabria, Italy: Compositional Record of Wedge-Top Partitioning Journal of Sedimentary Research, October 1, 2008; 78(10): 693 - 711. [Abstract] [Full Text] [PDF] |
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