Study On Mesozoic Lithofacies Paleogeography Of The Tethys Structural Area In The Western Mediterranean

Based on published literature,IHS database and a small amount of seismic,drilling and outcrop data,this paper divides the structural-stratigraphic units of Tethys structural area in the western Mediterranean,studies the main geological records of Mesozoic in different structural-stratigraphic zones,analyzes the geological evolution law of the study area,compiles the lithofacies paleogeographic map of four strata of Mesozoic Triassic,Jurassic,Upper Cretaceous and lower Cretaceous,and summarizes the lithofacies paleogeographic distribution law of different strata.The Tethys structural area in the western Mediterranean includes 495 basins,uplifts and other basic structural units.According to the structural-stratigraphic characteristics,these basic structural units can be grouped into five large structural-stratigraphic zones:(1)the Caledonian deformation belt in southern Europe,(2)the Variscan deformation belt in southern Europe,(3)the Iberian block and its surrounding Neoproterozoic-Paleozoic deformation belt,(4)the Cenozoic ocean basin and its surrounding Meso-Cenozoic deformation belt in the western Mediterranean and(5)the basin groups on the northwestern margin of the African continent.The Caledonian deformation belt in southern Europe is based on the Caledonian deformation metamorphic rocks,on which the Paleozoic,Mesozoic and Cenozoic are developed,and the Mesozoic is a littoral-neritic sea-salt marshto shallow sea environment dominated by clastic rock,carbonate rock and evaporite.The Variscan deformation belt in southern Europehas extensive Variscan deformation and metamorphic basement,and the alluvial area of Mesozoic gradually evolved into littoral-neritic sea.Only a small area of the Iberian massif has Mesozoic,and the periphery of the massif is shallow sea dominated by clastic and carbonate rocks.The bottom of the Cenozoic ocean basin and its surrounding Meso-Cenozoic deformation belt in the western Mediterranean is littoral-neritic sea-salt marsh,mainly developed evaporite + clastic rock,and gradually evolved into a shallow sea environment,mainly developed clastic rock and carbonate rock.The basin groups on the northwestern margin of the African continentis based on Pan-African period metamorphic rocks and magmatic rocks.The Mesozoic is mainly composed of clastic rocks,carbonate rocks and evaporites.The exposed denudation area in the northeast is gradually reduced and finally evolved into a shallow sea environment.In the Tethys structural area of the western Mediterranean,there are 12 kinds of lithologic assemblages with PALEOGEOGRAPHIC SIGNIFICANCE,which are represented by clastic rock,carbonate rock and evaporite.There are six paleogeographic environments,including alluvial area,semi deep sea-deep sea area,shallow sea area,submarine fan,littoral-neritic sea-salt marsh and exposed denudation area.The distribution of lithofacies paleogeography is controlled by the evolution of Tethys ocean.In the Triassic,most of the Tethys structural area of the western Mediterranean are characterized by evaporite + clastic rock in littoral-neritic sea-salt marsh.In the Jurassic,the exposed denudation area is reduced,and the sedimentary area is dominated by carbonate and clastic rocks.The shallow sea area of the lower Cretaceous and the upper Cretaceous gradually expanded,and the carbonate rocks increased one by one.