Search results for "feature"
showing 10 items of 4091 documents
The carbonates of the Permian Lakes of North Massif central, France
1992
During the Permian, large fluvio-lacustrine basins occurred within the West European Hercynian chain. The deposits were mainly detrital (conglomerates, sandstones and pelites). The two studied sites, Couy borehole and Aumance basin contain several dolomitic beds alternating with pelites containing Ostracods. The carbonate layers constitute various dolomitized facies with dolosparite, laminated and bituminous dolomites, oolites, oncolites and stromatolites, and pedological nodules. Microfacies are varied. The dolomite crystals can be either isolated rhombs scattered in pelites or rhombs and xenomorphic crystals cementing sandstones; in dolomicrites, dolomicrosparites and dolosparites, crysta…
Students' field research extends knowledge of origin of a UNESCO World Heritage site in Germany
2003
In 1992, as part of field-based course work with the Earth science department of the Universitat Minz, students began to investigate the structures of oil shale basins located in the Sprendlinger Horst, a horst-type block forming the northeastern shoulder of the Tertiary Upper Rhine Graben in southwestern Germany (figure 1). The Sprendlinger Horst is mainly built up by Hercynian or pre-Hercynian basement, Permian sediments, and volcanic rocks, as well as by several Tertiary alkali basalts and rare Cretaceous trachytes. In 1992, it was unknown whether the oil shale basins were of tectonic, volcanic, or even of impact origin.
Coelobiontic communities in neptunian fissures of synsedimentary tectonic origin in Permian reef, southern Urals, Russia
2007
Sedimentary dykes in the Permian reef complexes of the Russian platform are well preserved and important in providing information about reef growth, the reef biota and, particularly, cavity-dwelling organisms and sediment sources. Two main fissure assemblages are recognized with N80° and N170° (late Asselian-early Sakmarian) and N130°–140° and N60° (Sakmarian-Artinskian) orientations. These contemporaneous orthogonal dyke sets present orientations corresponding to the regional tectonic fabric and a tectonic origin for fracturing associated with the foreland basin development. The largest dykes record eight lithofacies and several stages of fracture opening. Stromatoids and centimetre-thick …
A regional-scale discontinuity in western Sicily revealed by a multidisciplinary approach: A new piece for understanding the geodynamic puzzle of the…
2015
The results of an integrated stratigraphic, structural, geophysical, and geochemical study reveal the presence of a crustal discontinuity in western Sicily that, at present, runs roughly N-S along a band from San Vito Lo Capo to Sciacca (SVCS). The boundary between the two zones of this discontinuity is nearly orthogonal to the main thrust propagation of the Sicilian thrust-and-fold belt. The different Permian to Tertiary sedimentary evolution recorded by the two zones appears related to this discontinuity, with thick carbonate platforms in the western sector facing deep-water successions in the eastern one. The presence of Upper Triassic reefs, huge megabreccias bodies, and widespread subm…
Changes in vegetation spring dates in the second half of the twentieth century
2011
This study aims at estimating trends in spring phenology from vegetation index and air temperature at 2 m height. To this end, we have developed a methodology to infer spring phenological dates from Global Inventory Modeling and Mapping Studies GIMMS Normalized Difference Vegetation Index NDVI time-series, which are then extrapolated to the period 1948–2006 with the help of Reanalysis data, using its 2 m height air temperature parameter. First, yearly NDVI is fitted to a double-logistic function for the whole extent of the GIMMS database 1981–2003. This fitting procedure allows us to describe, on a yearly basis, the NDVI evolution for each pixel through the estimation of six parameters whic…
Nutrient impoverishment and limitation of productivity after 20 years of conservation management in wet grasslands of north-western Germany
2009
Abstract European wet grasslands are characterized by high diversity of plant and animal species but are threatened by intensive land use. Although preservation or restoration of species-rich wet grasslands requires low nutrient availability that could be achieved by long-term management, studies monitoring nutrient removal are lacking. Our objective was to assess the long-term effect of management (mowing twice a year without or with PK fertilization for 20 years) on (i) productivity and nutrient removal with the harvest, (ii) the type of nutrient limitation, and (iii) plant species richness in wet grasslands in north-western Germany considering the differences between organic and mineral …
Syntaxonomic survey of the class Pegano harmalae‐Salsoletea vermiculatae Br.‐Bl. & O. Bolos 1958 in Italy
2013
After a general outline on the syntaxonomical framework of the class Pegano harmalae-Salsoletea vermiculatae Br.-Bl. & O. Bolos 1958, the occurrence of this vegetation in the Italian territory is examined. In Italy, this vegetation is mostly found on clayish or marly substrata, particularly if slightly enriched with nitrates and chlorides. With reference to the Rivas-Martinez bioclimatic classification, the Italian stands have an infra- to thermo-Mediterranean thermotype (marginally up to the meso-Mediterranean one) with dry or arid ombrotype. In particular, this vegetation is well represented in Sicily, while in Sardinia and along the Italian Peninsula, it progressively becomes more rare a…
The most ancient ophiolite of the Central Asian fold belt: U–Pb and Pb–Pb zircon ages for the Dunzhugur Complex, Eastern Sayan, Siberia, and geodynam…
2002
Abstract Ophiolitic rocks with a zircon age of ∼1020 Ma occur in the Dunzhugur complex of East Sayan, Siberia, and are part of a Neoproterozoic to early Palaeozoic segment of the Central Asian fold belt. The most spectacular suite is exposed along the Oka and Bokson rivers, where a complete ophiolite sequence with mantle tectonites, a layered sequence composed of dunite, wehrlite, and pyroxenite, a gabbro section, a sheeted diabase dyke complex and basaltic pillow lavas are exposed. Petrologic and geochemical data suggest that all members of the ophiolite originally belonged to the same cogenetic mafic–ultramafic crustal section and support a supra-subduction zone setting in a fore-arc rift…
Surface expression of eastern Mediterranean slab dynamics: Neogene topographic and structural evolution of the southwest margin of the Central Anatol…
2012
[1] The southwest margin of the Central Anatolian Plateau has experienced multiple phases of topographic growth, including the formation of localized highs prior to the Late Miocene that were later affected by wholesale uplift of the plateau margin. Our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1.5 km elevation to <7.17 Ma, and regional lithostratigraphic correlations imply that the age is <6.7 Ma. Single-grain CA-TIMS U-Pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10.6 Ma, indicating a maximum age that is consistent with the biostratigraphy. Our structural measurements within the upl…
Distinguishing between Bos and Bison petrous bones. A case study: Bovines from the des-cubierta cave (Pinilla del Valle, Madrid)
2019
This research has been supported by the financial assistance of the Spanish Society of Palaeontology ID AJISEP-2017-07142. M.A. Galindo-Pellicena was also being supported by a postdoctoral grant from the Fundacion Atapuerca. We thank the Excavation Team of the Des-Cubierta cave for their work in the fi eld, and our colleagues from the Centro Mixto UCM-ISCIII of Madrid and from the Regional Archaeological Museum of Alcalá de Henares, especially to Belén Márquez, Elena Santos, Beatrice Vacca and Abel Moclánfor their suggestions during the elaboration of the manuscript. Thanks must be extended to the Restoration Team, especially to M. Cruz Ortega, to the photographers Alfonso Dávila and Mario …