This paper deals with thepetrographic, geological, stratigraphic and structuralaspects of subaerial mid-Pliocene to Pleistocenevolcanic rocks outcropping in the northern sector ofthe lblean Plateau.In the examined area, almost the entire lbleansedimentary and eruptive sequence, from LateCretaceous to Holocene, outcrops. Three mainsedimentary cycles are identified.A detailed field survey has revealed the linkbetween magmatism and extensional-transtensionaltectonics the latter principally connected to thestructural NE-SW direction and characterised byboth strike-slip and vertical movements. Inparticular, the late Miocene volcanic products(Lower Volcaniclastic Deposits) are connected withthe mid-Miocene tectonic phase and represent arevival of basic eruptive activity after the lateCretaceous-early Tortonian hiatus. Similarly, themid-late Pliocene/early Pleistocene volcanic activityis linked to the mid-Pliocene tectonic phase.On the whole, the composition of the volcanicproducts ranges from nephelinite - ankaratrite totholeiite, without any correlation with spatialdistribution or age.Subaerial Plio-Pleistocene volcanism emittedI 0-15 km3 of products. Subalkaline products prevailover alkaline ones (tholeiite 62%; basanite 22%; alkali-basalt 8%; hawaiite 4%; transitional basalt3%; nephelinite and ankaratrite 1% ).These products are the result of partial melting ofdifferent metasomatised spinel peridotitelithospheric sources. The partial melting fractionprogressively increases and source depth decreasesfrom strongly alkaline to tholeiitic magmas.The alignment of eruptive centres with thetectonic features, together with the petrographic andgeochemical features of the volcanites, indicate thatthe magma rose directly from the mantle along faultplanes.
|Titolo:||Subaerial Plio-Pleistocene volcanism in the geo-petrographic and structural context of the north-central Iblean region (Sicily)|
|Data di pubblicazione:||2002|
|Appare nelle tipologie:||1.1 Articolo in rivista|