20 research outputs found
The inventory of geological heritage of the state of SĂŁo Paulo, Brazil: Methodological basis, results and perspectives
An inventory of geological sites based on solid and clear criteria is a first step for any geoconservation strategy. This paper describes the method used in the geoheritage inventory of the State of SĂŁo Paulo, Brazil, and presents its main results. This inventory developed by the geoscientific community aimed to identify geosites with scientific value in the whole state, using a systematic approach. All 142 geosites representative of 11 geological frameworks were characterised and quantitatively evaluated according to their scientific value and risk of degradation, in order to establish priorities for their future management. An online database of the inventory is under construction, which will be available to be easily consulted and updated by the geoscientific community. All data were made available to the State Geological Institute as the backbone for the implementation of a future state geoconservation strategy.The authors acknowledge the Science Without Borders Programme, Process 075/2012, which supported this study and the SĂŁo Paulo Research Foundation (FAPESP), Process 2011/17261-6. We also thanks C. Mazoca for his help with maps and figures.info:eu-repo/semantics/acceptedVersio
Palaeogeographical reconstructions of Upper Permian to Middle Triassic of South-Western European basins: new sedimentological data from Minorca (Balearic Islands, Spain).
International audienc
A paleoenvironmental analysis of Permian sediments in Menorca (Balearic Islands, Spain) with new palynological and megafloral data.
International audienc
High-latitude ice and climate control on sediment supply across SW Gondwana during the late Carboniferous and early Permian
International audienceThe response of sediment routing to climatic changes across icehouse-to-greenhouse turnovers is not well documented in Earthâs pre-Cenozoic sedimentary record. Southwest Gondwana hosts one of the thickest and most laterally extensive records of Earthâs penultimate icehouse, the late Paleozoic ice age. We present the first high-resolution U-Pb zircon chemical abrasionâisotope dilutionâthermal ionization mass spectrometry (CA-ID-TIMS) analysis of late Paleozoic ice age deposits in the Kalahari Basin of southern Africa, which, coupled with existing CA-ID-TIMS zircon records from the ParanĂĄ and Karoo Basins, we used to refine the late Paleozoic ice age glacial history of SW Gondwana. Key findings from this work suggest that subglacial evidence in the Kalahari region is restricted to the Carboniferous (older than 300 Ma), with glacially influenced deposits culminating in this region by the earliest Permian (296 Ma). The U-Pb detrital zircon geochronologic records from the ParanĂĄ Basin of South America, which was located downstream of the Kalahari Basin in the latest Carboniferous and Permian, indicate that large-scale changes in sediment supplied to the ParanĂĄ were contemporaneous with shifts in the SW Gondwana ice record. Gondwanan deglaciation events were associated with the delivery of far-field, African-sourced sediments into the ParanĂĄ Basin. In contrast, Gondwanan glacial periods were associated with the restriction of African-sourced sediments into the basin. We interpret the influx of far-field sediments into the ParanĂĄ Basin as an expansion of the catchment area for the ParanĂĄ Basin during the deglaciation events, which occurred in the latest Carboniferous (300â299 Ma), early Permian (296 Ma), and late early Permian (<284 Ma). The coupled ice and detrital zircon records for this region of Gondwana present opportunities to investigate climate feedbacks associated with changes in freshwater and nutrient delivery to late Paleozoic ocean basins across the turnover from icehouse to greenhouse conditions
Palynostratigraphic Data for the Buntsandstein and Muschelkalk Facies from the Iberian Ranges (Spain)
International audienceThis work presents results of a compilation of all published palynological data as well as other unpublished data, on the basis of which a unified palynological biozonation is proposed for the Buntsandstein and Muschelkalk facies from the Iberian Ranges (Spain)
The PermianâTriassic transition and the onset of Mesozoic sedimentation at the northwestern peri-Tethyan domain scale: Palaeogeographic maps and geodynamic implications
The main aim of this paper is to review Middle Permian through Middle Triassic continental successions in
European. Secondly, areas of MiddleâLate Permian sedimentation, the PermianâTriassic Boundary (PTB) and
the onset of Triassic sedimentation at the scale of the westernmost peri-Tethyan domain are defined in order
to construct palaeogeographic maps of the area and to discuss the impact of tectonics, climate and sediment
supply on the preservation of continental sediment.
At the scale of the western European peri-Tethyan basins, the Upper Permian is characterised by a general
progradational pattern from playa-lake or floodplain to fluvial environments. In the northern Variscan Belt
domain, areas of sedimentation were either isolated or connected to the large basin, which was occupied by
the Zechstein Sea. In the southern Variscan Belt, during the Late Permian, either isolated endoreic basins
occurred, with palaeocurrent directions indicating local sources, or basins underwent erosion and/or there
was no deposition. These basins were not connected with the Tethys Ocean, which could be explained by a
high border formed by CorsicaâSardinia palaeorelief and even parts of the Kabilia microplate. The palaeoflora
and sedimentary environments suggest warm and semi-arid climatic conditions.
At the scale of the whole study area, an unconformity (more or less angular) is observed almost everywhere
between deposits of the Upper Permian and Triassic, except in the central part of the Germanic Basin. The
sedimentation gap is more developed in the southern area where, in some basins,Upper Permian sediment does not
occur. The large sedimentary supply, erosion and/or lack of deposition during the Late Permian, as well as the
variable palaeocurrent direction pattern between theMiddleâLate Permian and the Early Triassic indicate a period of
relief rejuvenation during the Late Permian. During the Induan, all the intra-belt basins were under erosion and
sediment was only preserved in the extra-belt domains (the northern and extreme southern domains). In the
northern domain (the central part of the Germanic Basin), sediment was preserved under the same climatic
conditions as during the latest Permian, whereas in the extreme southern domain, it was probably preserved in the
Tethys Ocean, implying a large amount of detrital components entering themarinewaters. Mesozoic sedimentation
began in the early Olenekian; the ephemeral fluvial systems indicate arid climatic conditions during this period.
Three distinct areas of sedimentation occur: a northern and southern domain, separated by an intra-belt domain.
The latter accumulated sediments during the EarlyâMiddle Permian and experienced erosion and/or no-deposition
conditions between the MiddleâLate Permian and the beginning of Mesozoic sedimentation, dated as Anisian to
Hettangian. At the top of the Lower Triassic, another tectonically induced, more or less angular unconformity is
observed: the Hardegsen unconformity, which is dated as intra-Spathian and is especially found in the North
European basins. This tectonic activity created new source areas and a new fluvial style, with marine influences at
the distal part of the systems. During the Anisian and Ladinian, continental sedimentation was characterised by a retrogradational trend. In other words, the fluvial system evolved into fluvio-marine environments, attesting to a
direct influence of the Tethys Ocean in the southern and northern domains. Both at the end of the Olenekian
(Spathian) and during the Anisian, the presence of palaeosols, micro- andmacrofloras indicate less arid conditions
throughout this domai