Search results for " stratigraphy"
showing 10 items of 79 documents
Freshening of the Mediterranean Salt Giant: controversies and certainties around the terminal (Upper Gypsum and Lago-Mare) phases of the Messinian Sa…
2021
The late Miocene evolution of the Mediterranean Basin is characterized by major changes in connectivity, climate and tectonic activity resulting in unprecedented environmental and ecological disruptions. During the Messinian Salinity Crisis (MSC, 5.97-5.33 Ma) this culminated in most scenarios first in the precipitation of gypsum around the Mediterranean margins (Stage 1, 5.97-5.60 Ma) and subsequently > 2 km of halite on the basin floor, which formed the so-called Mediterranean Salt Giant (Stage 2, 5.60-5.55 Ma). The final MSC Stage 3, however, was characterized by a "low-salinity crisis", when a second calcium-sulfate unit (Upper Gypsum; substage 3.1, 5.55-5.42 Ma) showing (bio)geochemica…
Calabrian and Ionian: A proposal for the definition of Mediterranean stages for the Lower and Middle Pleistocene
2006
The need to standardise stratigraphical subdivisions of continuous marine sedimentary successions that outcrop for hundreds metres, using clearly defined points fixed in the field is strongly felt. A proposal is presented here to formalize regional stages for the Lower Pleistocene (Calabrian) and for the Middle Pleistocene (Ionian) in Italy. The sections are well exposed, carefully investigated using multiple criteria (an integrated stratigraphical approach) and located in the central part of the Mediterranean. This area is recognized worldwide as a classical region for the Neogene and the Pleistocene sequences. The terrestrial record is directly correlated with the deep-sea record, as dete…
Pliocene sapropels in the northern Adriatic area: chronology and paleoenvironmental significance
1997
Abstract A detailed stratigraphic and paleoenvironmental study was carried out ona marine section from the Marecchia Valley in the Northern Apennines. The section consists predominantly of deep-water hemipelagic clays intercalated with 15 thick, laminated sapropels (M1–M15). Based on biostratigraphic (calcareous nannoplankton and planktonic foraminifera) and magnetostratigraphic results, the Marecchia Valley section is interpreted as being middle to late Pliocene in age, extending from the upper part of the Gauss Chron to the lower part of the Matuyama Chron. The high resolution stratigraphy allows us to correlate, for the first time, these northern Italian sapropels with sapropels previous…
Sedimentology, petrography and geochemistry of a limestone breccia (Pietra di Billiemi) from NW Sicily, Italy: implications for evolution of the Teth…
2009
In this study, the Pietra di Billiemi, a famous dimension stone, is investigated because it records the tectonic evolution of the south Tethys continental margin and preserves a record of major environmental changes occurring near the Triassic/Jurassic boundary. The Pietra di Billiemi is a grey, coarse-grained and clast-supported limestone breccia cropping out in an area of the Palermo Mountains representing a segment of the Apennine–Maghrebian chain in western Sicily. The rock consists of metre-sized to centimetre-sized angular clasts, derived from Upper Triassic sponge boundstones and rudstones, with a differently coloured, silt-grained matrix. Fitted fragments are observed commonly which…
Microbial deposits in the aftermath of the end-Permian mass extinction: A diverging case from the Mineral Mountains (Utah, USA)
2015
40 pages; International audience; The Lower Triassic Mineral Mountains area (Utah, USA) preserves diversified Smithian and Spathian reefs and bioaccumulations that contain fenestral-microbialites and various benthic and pelagic organisms. Ecological and environmental changes during the Early Triassic are commonly assumed to be associated with numerous perturbations (productivity changes, acidifica-tion, redox changes, hypercapnia, eustatism and temperature changes) post-dating the Permian–Triassic mass extinction. New data acquired in the Mineral Mountains sediments provide evidence to decipher the relationships between depositional environments and the growth and distribution of microbial …
The “chessboard” classification scheme of mineral deposits: Mineralogy and geology from aluminum to zirconium
2010
Abstract Economic geology is a mixtum compositum of all geoscientific disciplines focused on one goal, finding new mineral depsosits and enhancing their exploitation. The keystones of this mixtum compositum are geology and mineralogy whose studies are centered around the emplacement of the ore body and the development of its minerals and rocks. In the present study, mineralogy and geology act as x - and y -coordinates of a classification chart of mineral resources called the “chessboard” (or “spreadsheet”) classification scheme. Magmatic and sedimentary lithologies together with tectonic structures (1 - D/pipes, 2 - D/veins) are plotted along the x -axis in the header of the spreadsheet dia…
The Neanderthalian molar from Hunas, Germany
2005
Abstract In this paper, we present a well-preserved isolated human molar found in 1986 in the Hunas cave ruin, south-east Bavaria. The tooth was located at the bottom of layer F2, which belongs to a long stratigraphic sequence comprising faunal remains as well as archaeological levels (Mousterian). A stalagmite from layer P at the base of the stratigraphic sequence was recently dated to 79.373±8.237 ka (base) and 76.872±9.686 ka (tip) by TIMS-U/Th (Stanford University). We identified the tooth as a right (possibly third) mandibular molar. Characteristic parameters such as crown and root morphology, fissure pattern, enamel thickness, occlusal and interproximal wear, dental dimensions and ind…
LES VARIATIONS DU NIVEAU MARIN SUR LE BASSIN DE PARIS AU BATHONIEN-CALLOVIEN. IMPACTS SUR LES COMMUNAUTÉS BENTHIQUES ET SUR L'ÉVOLUTION DES ORNITHELL…
1992
The study deals with the biological impacts of sea-Ievel changes on evolution of a Jurassic benthic fossil group (Ornithellida, Brachiopoda). The different time and scale at which the shifts in marine environments occur leads to the recognition of three interacting dynamic systems: environmental, communities, populations dynamics. The analysis is thus divided into a three steps hierarchy: sequence stratigraphy, analysis of the diversity of brachiopod assemblages, and analysis of morphological variations within omithellid populations. Sequence stratigraphy of the Dogger marly and carbonate successions in the Paris basin provides accurate correlations of depositional environments from shallow…
A sequence analyzed from the basin to the platform : the Middle Oxfordian calcareous succession in southeastern France
2004
Abstract Middle Oxfordian sedimentation is very homogeneous in southeastern France. It is characterized by a specific alternation of marls and fine-grained limestones (G. transversarium Zone). This work shows that sets of calcareous beds allow accurate stratigraphic correlations in various paleogeographic areas, from the shallow Jura platform to the deep Dauphinois basin. Following a rifting period, this sedimentation illustrates a doming period with decreasing subsidence and water depth. This corresponds to the establishment of a wide marine area more favourable to carbonate sedimentation. Considering sequence stratigraphy, some slight variations occur in the sediment record and lead to in…
The lower and middle Pleistocene geological record of the San Lorenzo lacustrine succession in the Sant’Arcangelo Basin (Southern Apennines, Italy)
2005
The Sant’Arcangelo Basin is located in the southern part of the Apennine chain (Basilicata). It is filled by a siliciclastic sequence 3500m thick, dated to the Late Pliocene–Middle Pleistocene time interval. In this basin an Early Middle Pleistocene fluvio-lacustrine sequence, known as San Lorenzo Cycle, has been recognised. In the upper part of the sequence, in Rifreddo, a fairly diversified small vertebrate assemblage has been recovered. The occurrence of Mimomys savini allows to the fauna to be considered as Biharian. The presence of some faunal elements such as Microtus (Terricola) arvalidens, Microtus (Iberomys) ex gr. huescarensis-brecciensis, and Macroneomys cf. brachygnathus restric…