Multiple source provenance of sediments and submarine fan formation are herein investigated based on Quaternary sandy barriers of the Brazilian Southernmost Coastal Plain.LA-ICP-MS dating on 1625 detrital zircons from...Multiple source provenance of sediments and submarine fan formation are herein investigated based on Quaternary sandy barriers of the Brazilian Southernmost Coastal Plain.LA-ICP-MS dating on 1625 detrital zircons from marine and aeolian facies sands of four successive lagoon-barrier systems are analyzed.The characterization of Archean to Pleistocene zircons into a younger Andean(22±4 Ma to 1±1 Ma,48 from 1625),Mesozoic to Paleozoic,and Mesoproterozoic(479 from 1622)populations suggest that the main feeding of sediments to the coastal plain occurred through the La Plata River drainage system.The significant contribution of sediments is transported from the mouth of La Plata River northward by longshore circulation(littoral drift).Minor contributions are also recognized as.a farther source associatedwith the Patagonia drainage and nearby source related to the Uruguay/Rio Grande do Sul Shield and the ParanáBasin,drained by the Camaquãand Jacuírivers.The latter one is recognized by the contribution fromNeoproterozoic to Early Paleozoic,and some Paleoproterozoic and Archean zircon grains.The definition of the sources of clastic sediments allows inferences about the origination of Rio Grande Fan where both the cold Falkland and the warm Brazil currents played a major role.展开更多
In this paper, a collection of statistical correlation methods is used in the study of aquifer potentials in Abia State of south-eastern Nigeria. The Physiology, geomorphology and hydrogeology of the area are first pr...In this paper, a collection of statistical correlation methods is used in the study of aquifer potentials in Abia State of south-eastern Nigeria. The Physiology, geomorphology and hydrogeology of the area are first presented. Sixty-six Vertical Electrical Sounding (VES) data sets are used to determine the aquifer. Demographic studies are then carried out in 220 communities in order to determine the relationship between population size on one hand and a unit draw-down of wells due to groundwater abstraction on the other. The relationship between geological Formation, aquifer potentials and depth of boreholes are then calculated using Pearson’s correlation matrix. Results show that the mean population of persons appears to be higher in Bende-Ameki Formation (of Eocene-Oligocene age) and the late Tetiary-Early Quaternary Coastal Plain Sands, than in the Cretaceous shale Formation of Asata Nkporo. The mean population of persons sitting on these Formations is 31,200, 18,370 and 5400 respectively. Furthermore, it is observed that a population increase of about 50 persons in a community in Abia State is accompanied by a unit volume (1 m3) draw-down of wells due to groundwater abstraction. It is therefore concluded that population size is positively correlated with groundwater abstraction, aquifer potentials and geological Formation favouring aquifer in Abia State.展开更多
基金the Brazilian Scholarship Agency(CAPES) for the scholarship to the second author (JJC)the National Council for Scientific and Technological Development–CNPq for the financial support (grant#305053/2014-0).
文摘Multiple source provenance of sediments and submarine fan formation are herein investigated based on Quaternary sandy barriers of the Brazilian Southernmost Coastal Plain.LA-ICP-MS dating on 1625 detrital zircons from marine and aeolian facies sands of four successive lagoon-barrier systems are analyzed.The characterization of Archean to Pleistocene zircons into a younger Andean(22±4 Ma to 1±1 Ma,48 from 1625),Mesozoic to Paleozoic,and Mesoproterozoic(479 from 1622)populations suggest that the main feeding of sediments to the coastal plain occurred through the La Plata River drainage system.The significant contribution of sediments is transported from the mouth of La Plata River northward by longshore circulation(littoral drift).Minor contributions are also recognized as.a farther source associatedwith the Patagonia drainage and nearby source related to the Uruguay/Rio Grande do Sul Shield and the ParanáBasin,drained by the Camaquãand Jacuírivers.The latter one is recognized by the contribution fromNeoproterozoic to Early Paleozoic,and some Paleoproterozoic and Archean zircon grains.The definition of the sources of clastic sediments allows inferences about the origination of Rio Grande Fan where both the cold Falkland and the warm Brazil currents played a major role.
文摘In this paper, a collection of statistical correlation methods is used in the study of aquifer potentials in Abia State of south-eastern Nigeria. The Physiology, geomorphology and hydrogeology of the area are first presented. Sixty-six Vertical Electrical Sounding (VES) data sets are used to determine the aquifer. Demographic studies are then carried out in 220 communities in order to determine the relationship between population size on one hand and a unit draw-down of wells due to groundwater abstraction on the other. The relationship between geological Formation, aquifer potentials and depth of boreholes are then calculated using Pearson’s correlation matrix. Results show that the mean population of persons appears to be higher in Bende-Ameki Formation (of Eocene-Oligocene age) and the late Tetiary-Early Quaternary Coastal Plain Sands, than in the Cretaceous shale Formation of Asata Nkporo. The mean population of persons sitting on these Formations is 31,200, 18,370 and 5400 respectively. Furthermore, it is observed that a population increase of about 50 persons in a community in Abia State is accompanied by a unit volume (1 m3) draw-down of wells due to groundwater abstraction. It is therefore concluded that population size is positively correlated with groundwater abstraction, aquifer potentials and geological Formation favouring aquifer in Abia State.
