The neogene of the Lower Tagus Basin (Portugal)

The Tertiary Lower Tagus Basin (LTB) occupies a large area in Portugal and constitutes symmetric basin of the oriental huge Upper Basin, centered at Madrid (Spain). LTB was an endorreic during Paleogene. Marine connection occurred Aquitanian; Lisbon – Setubal Peninsula region sedimentation ocean/continent interface, with several changes coast line. Apparently, first marine transgression came from South, originating gulf N-S coral reef that attained area. Occidental communication to sea established after Burdigalian.The sedimentary palaeontologic record distal sector (Lisbon–Setubal Peninsula) is related level changes. It possible correlate levels planctic foraminifera mammals, as well get isotopic ages (K/Ar glauconites; 87 Sr/ 86 Sr). Good biostratigraphic data can be obtain continental coastal deposits. fossil richness dinoflagellates, spores, pollen, plant macrorremains, foraminifera, ostracoda, molluscs, echinids, fishes, reptiles, mammals O C isotopes, source information for environmental palaeogeographical reconstitutions, establishment correlations between analysis integration amount lithological biostratigraphical joined Sr), allow establishement chronostratigraphic framework part Miocene definition 10 depositional sequences, agreeing Haq’s 3rd order eustatic cycles. Climatic evolution has been also characterized. At environments, faunas floras point out alternation moist dry episodes, dryest one Langhian. For inland, two sectors Near directly affected by (Ribatejo Alto Alentejo) deposits are wandering Pre-Tagus fluvial plain. During Middle detrital represented. Some marls oysters denounce high levels; brackish waters attain regions 150 km far extant vertebrate fossils sites region, namely Tortonian. Sedimentary conditions changed Miocene. right bank Tagus, limestones accumulate lacustre palustre environments; latteraly thick clay strecht left bank. proximal areas (Beira Baixa) chronostratigraphical controle poor. outcrops largely discontinuous. only define alostratigraphic units, bounded regional unconformities, resulting tectonic events recognized Iberia scale. Miocene, sandy braided system installed, draining plain NE SW. Plant macro-remains indicate warmer moister climate than today. Hispanotherium matritensis (steppe rhinoceros) known East Castelo Branco (Plasencia, Spain); it characteristic MN5 zone (Astaracian) Lisbon’s Younger (Upper Tortonian Messinian) correspond alluvial fan sediments occur near slopes, base rising mountains (Portuguese central chain); thickness granulometry quickly decrease downstream. Pliocene overlay through erosion surface (Setubal clays Vallesian Ribatejo (inland). Zanclean carried on deposition conglomerates. Away mountain feeder relieves, show thickness; alternating conglomerates lutites were deposited. A temperate mediterranean contrasting seasons prevailled. In Piacenzian, fans systems installed Atlantic, preceding actual hydrographical net. Feldspatic sands deposited Peninsula; line west actual. took place over littoral, affecting