La ricostruzione paleoclimatico-ambientale dell'Appennino umbro-marchigiano, durante il Pleistocene Medio e Superiore, attraverso lo studio dei depositi in Grotta

Among the natural archives were formed in continental environments, have a prominent place the concretions in caves (speleothems) and fine sediments. In fact, the karst caves are traps sediments as paleoenvironmental information is generally stored in the memory of what happens around them, including the external system, where processes of erosion and alteration, generally, they suppress any evidence of previous environmental evolution. In recent decades, the research related to the study of the physico-chemical properties of concretional deposits (speleothems), or the fine sediments in the cave, was consequently a considerable acceleration in particular with regard to the paleoclimatic and paleoenvironmental reconstructions for the Quaternary. The caves represent, then, very important sites of research of the fossil plant that, trapped in sediments, in calcite or/and gypsum concretions, allow to palinologist and geologist to discover plant change through geological ages and, then, the climate variations during the Quaternary age. The goal of this thesis is the study of a caves in the umbro-marchean Apennines (Marche region, central Italy) and, in particular, the two karts complexes: karst Complex of Frasassi and karst Complex of Caprelle. This research has been led on two fronts strictly interrelated, one of geomorphological/geochronological study and the second of palinological analysis. The second allowed the paleoclimatic and paleoflora-vegetation reconstruction when the two karst complexes were going to be formed and gave a contribute to chronological placement of deposits. This research began by collecting samples in Frasassi Complex (10 samples belonging to different karst levels and in different caves of the wide Complex) and in Caprelle Complex (9 samples collected at different sites and depth, down to about 75 metres). Sampled sediments have been treated for pollen extraction (this method provides deflocculation by Na-pyrophosphate 10%, solution of carbonates by HCl 10%, acetolysis by Erdtman 1960, enrichment with heavy liquid Na-metatungstate hydrate, solution of silicates by HF 40%), in the Paleobotany and Pollen Analysis Laboratory of Modena and Reggio Emilia University. The results gave an enough pollen quantity, from some studied samples, and the data are consistent with the typology of substrates usually studied in speleo-palinology. Collected pollen, as expected, had a good/excellent state of conservation, so to allow an easier identification. Through the study of these two karst complexes, this research intends to give a contribute to the knowledge of environmental elements, to the reconstruction of paleoenvironmental and paleoclimatic of the karst area in the umbro-marchean area, in some cases obtaining documents handy to understanding cave's and deposits genesis, during the karst complex evolution. The whole umbro-marchean Apennines is constituted by sedimentary rocks (CALAMITA and PIERANTONI, 1993; DEIANA et al., 2002). Also on the ground are well clear the effects of the deforming and compressive tectonic phases, happened during the Neogene, and of extensional ones happened during the Quaternary. During this last period, at last, most evident alterations of landscape result caused by surface and depth karst processes with genesis of caves (speleogenesis). Such researches were begun in bogs, swamps and ponds, in the sixties and carried on till nowdays, enriched since the eighties by palinological analysis conducted in hypogeum environments. Deposits of Frasassi e Caprelle have given an important contribute to paleoenvironmental reconstruction of Pleistocene in Italy and particularly in Central Italy. Various past and recent italian sequences have been analysed, based on pollen data quality and an adeguate chronostratigraphy reference frame, and were indispensable for doing a comparison with palinological records of karst complexes of Frasassi and Caprelle. In the study of cave sediments is very important to pay attention to the site where collect samples, in order to grant the possibility to find pollen in good quantity and so have the possibility to interrelate palinological analysis and geomorphological and geochronological data (absolute and relative chronologies). In Italy, only eight cave sites were studied by a palinological point of view. In some of these sites, as Grotta di Salomone and Sant'Angelo (Abruzzo region), concretions were studied, whereas on other caves palinological analysis were focused depth deposits. In Buco Bucone cave, in Grotta di Valle delle Vacche cave, in the Caprelle and Frasassi complexes sample sites were not at the surface but at a depth of 150 metres. Before this thesis, in Central Italy only three caves have been analysed by a palinological point of view