Search results for "Sedimentary"

Large- and small-mammal distribution patterns and chronostratigraphic boundaries from the Late Pliocene to the Middle Pleistocene of the Italian peni…

2007

Abstract Over the last 50 years the studies on terrestrial mammals of the Italian peninsula have provided a large volume of data and a more detailed knowledge of faunal events during the Late Pliocene and Quaternary. Moreover geological, sedimentological, palynological and magnetostratigraphical investigations on the Pliocene–Pleistocene continental sedimentary basins have yielded the possibility of a detailed calibration of the faunal successions. Thus, palaeontologists have been able to reconstruct faunal sequences and to propose biochronological scales based on large and small mammals, respectively. In the present contribution an integration of the two biochronological scales is proposed…

Organics versus clastics: conditions necessary for peat (coal) development

1990

Abstract The absence or lack of detrital influx into ancient peat-forming swamps is critical to the formation of low-ash coal. Modern and ancient coal-forming swamps of continental basins show a separation of peat and clastic sediments which is partially fault controlled. In the African rift valleys as well as in the Stephanian intermontane coal basins of France, thick peat free from clastic input may be the result of tectonic activity. In the paralic basins of Morocco (Westphalian B) and Nigeria (Late Cretaceous) coal occur landward of the shoreline turnaround and are related to a relative high stand of the sea, which curtailed detrital influx into the basins. Thus, peat formation occurred…

Geochemical constraints on the provenance and depositional setting of sedimentary rocks from the islands of Chios, Inousses and Psara, Aegean Sea, Gr…

2007

The provenance and depositional setting of Late Palaeozoic and Early Mesozoic clastic sediments from the eastern Aegean archipelago are examined here for the first time using whole-rock geochemistry and composition of detrital chrome spinel. Major- and trace-element data for Late Palaeozoic and Permo-Triassic clastic sediments from the Lower and Upper Units of Chios are compatible with an acidic to intermediate source, minor input of (ultra)mafic detritus and recycling of older sedimentary components. Chondrite-normalized REE profiles are uniform with light REE enrichments (La N /Yb N c . 7.7), negative Eu anomalies (Eu/Eu* c . 0.67) and flat heavy REE patterns (Gd N /Yb N c . 1.5), indicat…

Two-Stage Origin of K-Enrichment in Ultrapotassic Magmatism Simulated by Melting of Experimentally Metasomatized Mantle

2019

The generation of strongly potassic melts in the mantle requires the presence of phlogopite in the melting assemblage, while isotopic and trace element analyses of ultrapotassic rocks frequently indicate the involvement of subducted crustal lithologies in the source. However, phlogopite-free experiments that focus on melting of sedimentary rocks and subsequent hybridization with mantle rocks at pressures of 1&ndash

Fe–Mn-encrusted “Kamenitza” and associated features in the Jurassic of Monte Kumeta (Sicily): subaerial and/or submarine dissolution?

2000

Abstract An unusually jagged dissolution surface, capped by a thick Fe–Mn crust is well exposed in small quarry-cuts of the Jurassic of Monte Kumeta. It was formed on a crinoidal limestone substrate of Pliensbachian age, and is covered by Upper Bajocian Ammonitico Rosso-type sediments, all cross-cut by several generations of neptunian dykes. This peculiar surface is more or less coeval with hardgrounds, Fe–Mn-capped dissolution surfaces and associated neptunian dykes described from other localities of the Western Tethys and currently subject to fierce debates as to their purely submarine (or perhaps partly subaerial) origin. The major goal of this paper is to add new arguments to this debat…

Petrogenesis of tourmaline rocks associated with Fe-carbonate-graphite metapelite, metabasite and strata-bound polymetallic sulphide mineralisation, …

2007

Abstract Tourmalinite and tourmaline-rich rocks associated with Fe-carbonate–graphite phyllite, strata-bound polymetallic sulphide deposits, metabasite and marble were studied, for information on the mechanism of tourmaline formation in the pre-Hercynian low-grade metamorphic sequence of the Mandanici Unit in the Peloritani Mountains of Sicily, southern Italy. The major and trace element compositions of the tourmaline rocks suggest the existence of a sedimentary protolith with pre-metamorphic black shale and bedded chert. Boron was interpreted to be accumulated in a restricted sedimentary basin, between platform carbonate formations, with abundant organic matter and Fe–Al–Ti-rich laterite–b…

40 Ar/ 39 Ar ages of fallout tephra layers and volcaniclastic deposits in the sedimentary succession of the western Woodlark Basin, Papua New Guinea:…

2001

Lower pleistocene deposits in east part of the Favignana island, Sicily, Italy

2011

The Impact of Grain Size Composition and Organic Matter Content on Magnetic Susceptibility of Anthropogenically Transformed Bottom Sediments, as Exem…

2017

The article presents the results of an analysis of the surface layer of bottom sediments in the naval harbour in Hel. During field work conducted in June 2013, 54 sediment samples were collected. The aim of the study was to examine magnetic susceptibility of harbour sediment as a parameter determining the degree of anthropopressure. As part of laboratory tests, grain size analysis was performed in order to determine organic matter content and magnetic susceptibility of the sediment. The study also measured the impact of environmental factors on fluctuations in the other studied parameters. The results demonstrate increased dynamics of sedimentary environment in the open part of the naval ha…

Inverse modeling of past lead atmospheric deposition in South Greenland

2015

The aim of this study is to model atmospheric lead fluxes in two different paleoenvironmental records located in southern Greenland. Fifty five sediment samples collected from the Lake Igaliku sedimentary sequence were analyzed for lead and aluminum concentrations, and lead isotopic compositions. The second archive consists in a previously published dataset, obtained from a minerogenic peat deposit, located at Tasiusaq, 16 km northwest from Lake Igaliku. A flux model fitted to both dataset produces similar results, allowing past anthropogenic atmospheric deposition to be reconstructed. This original method can be easily adapted for other studies where natural inputs dominate over discrete a…