Rivista Italiana di Paleontologia e Stratigrafia, Volume 101, Numero 3
(1995), 381-388
LATE MIOCENE PALEOGEOGRAPHY OF THE MONTE SOLDANO AREA, SOUTHEASTERN PART OF
VOLTERRA BASIN, TUSCANY, ITALY
I.P. MARTINI1, V. PASCUCCI2 and F. SANDRELLI2
1Department of Land Resource Science, University of Guelph, ON Canada
2Dipartimento di Scienze della Terra, Universita' di Siena, Italy
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Several Upper Tortonian to Lower Messinian sedimentary facies were recognized
and mapped in the M.te Soldano area at the southeastern end of the extensional
Basin of Volterra in the Northern Apennines in Tuscany. They consist of (a)
disorganized coarse conglomerates, (b) organized conglomerates interbedded with
sandstone, (c) coarse to medium grained sandstone which is present both as
interlayers within the organized conglomerates as well as turbidite layers
interbedded with lacustrine clay, (d) marlstone rich in opercula of Bithynia,
and (e) lacustrine clay with few sandy turbidite interlayers. The vertical and
lateral distribution of these facies indicates the existence of a large alluvial
fan complex. The development of such a large complex from an apparently
relatively narrow sediment source area (an interbasin ridge) was possible
because the feeding rivers were probably located at the intersection between a
border fault and a fault associated with a transfer zone. This allowed for a
much wider drainage basin.
