Search results for "Siliciclastic"
showing 10 items of 51 documents
Strength of pre-Roman amphorae: Comparison of the different types
2015
Abstract Given that amphorae were used for storage or for long and/or short distance transport, they must have been able to retain their content and, at the same time, be able to resist important load during transport. This paper concerns aspects of the techno-functionality of pre-Roman Iberian amphorae. The basic performance requirement concerned here is the mechanical strength (transverse rupture strength: TRS). Strength is related to the adequacy for storage or short and/or long distance transport that, up to now, is only assessed by typological identification or archaeological evidence. Experimental implementation on actual archaeological material has confirmed that strength increased w…
Lithologic composition of the Earth's continental surfaces derived from a new digital map emphasizing riverine material transfer
2005
[1] A new digital map of the lithology of the continental surfaces is proposed in vector mode (n ≈ 8300, reaggregated at 0.5° × 0.5° resolution) for 15 rock types (plus water and ice) targeted to surficial Earth system analysis (chemical weathering, land erosion, carbon cycling, sediment formation, riverine fluxes, aquifer typology, coastal erosion). These types include acid (0.98% at global scale) and basic (5.75%) volcanics, acid (7.23%) and basic (0.20%) plutonics, Precambrian basement (11.52%) and metamorphic rocks (4.07%), consolidated siliciclastic rocks (16.28%), mixed sedimentary (7.75%), carbonates (10.40%), semi- to un-consolidated sedimentary rocks (10.05%), alluvial deposits (15…
Fracture stratigraphy and oil first migration in Triassic shales, Favignana Island, western Sicily, Italy
2021
This study aims at evaluating the control exerted by fracture stratigraphy and diagenetic processes on oil first migration through an outcropping, mixed carbonate-siliciclastic succession. The present work included results of sedimentological, paleontological, mineralogical, petrographic, structural, and microstructural analyses carried out on organic-rich shales exposed at the Favignana Island of Sicily, Italy. The analyses focus on Upper Triassic yellowish siltstones and greyish laminated dolomitic limestones, which form a 10's of m-thick succession exposed along the westernmost portion of the Sicilian fold-and-thrust belt. The studied succession deposited in a coastal lagoon associated t…
Bulk carbonate isotope stratigraphy from CRP-3 core (Victoria Land Basin, Antarctica): evidence for Eocene–Oligocene palaeoclimatic evolution
2005
Bulk carbonate isotope compositions and carbonate petrography from upper Eocene and lower Oligocene siliciclastic sediments of the CRP-3 sediment core (Victoria Land Basin, Antarctica) have been investigated with the aim of contributing to reconstruction of the Antarctic Cenozoic palaeoclimate. Most of the carbonate is calcite cement occurring as patches, nodules and horizons and consisting of equant and/or drusy sparry calcite, pervasive blocky calcite and rare poikilotopic calcite spar. 18O-depleted values (from −17 to −8 δ‰) of the CRP-3 carbonates suggest that the precipitating fluids were a mixing between marine and meteoric waters from melting glaciers. The δ18O record exhibits a numb…
Diagénesis, análisis de procedencia y ambiente tectónico de rocas siliciclásticas. Un caso de estudio en el Devónico Superior de la Cordillera Ibéric…
2022
This paper describes the petrography and infers the provenance of siliciclastic rocks from the Upper Devonian of the Iberian Chains (Tabuenca, NE Spain), and outlines the tectonic setting associated with the Ebro Massif. These Devonian deposits are constituted by four different siliciclastic units: the Rodanas, Bolloncillos, Hoya and Huechaseca Formations. The provenance and diagenesis of over 400 sedimentary rocks samples are studied with a combination of petrographic polarizing microscope, scanning electron microscopy, atomic absorption spectroscopy, X-ray fluorescence and X-ray diffraction. In this sense, AAS and XRF analysis were used to determine the content of Ca, Mg, Fe, Mn, Na, K an…
Evolution of depositional settings in the Torrey area during the Smithian (Early Triassic, Utah, USA) and their significance for the biotic recovery
2015
This work focuses on well-exposed Lower Triassic sedimentary rocks in the area of Torrey (south-central Utah, USA). The studied Smithian deposits record a large-scale third-order sea-level cycle, which permits a detailed reconstruction of the evolution of depositional settings. During the middle Smithian, peritidal microbial limestones associated with a rather low-diversity benthic fauna were deposited seaward of the tidal flat siliciclastic red beds. Associated with siliceous sponges, microbial limestones formed small m-scale patch reefs. During the late middle to late Smithian interval, the sedimentary system is characterized by tidal flat dolostones of an interior platform, ooid-bioclast…
Stranded jellyfish in the lowermost Cambrian (Corduban) of Spain
2021
Ninety discoid structures of big size occurring on a bedding plane of Nemakit-Daldynian to Tommotian sandstones (i.e. Corduban in the Spanish scale of Cambrian stages) from south-western Spain are described. Cross-cutting relationships between discoid structures and associated trace fossils, as well as evidence for penecontemporaneous deformation of sediment laminae below the discoids, permit to interprete these structures as impressions of ancient, soft-bodied marine organisms. Taphonomic, biometric, and morphological studies suggest that they are outer moulds of both sides, subumbrellar and exumbrellar, of ancient jellyfish of hydrozoan coelenterates, whose canals resemble the modern genu…
New trepostomate bryozoans from the Upper Ordovician of Morocco and the temperature influence on zooid size
2015
AbstractNew Upper Ordovician trepostomate bryozoans from the eastern Anti-Atlas of Morocco have been identified. They have been collected from the lower and intermediate units of the Khabt-el-Hajar Formation, late Katian in age, representing, respectively, bryozoan-pelmatozoan meadows with siliciclastic input, degraded by wave activity in a mid-ramp setting, and outer-ramp environments with marly substrates. Ten species of the generaCyphotrypa,Calloporella,Diplotrypa,Parvohallopora,Dekayia, andAostiporaare described. Of them, three species are new:Cyphotrypa regularisJiménez-Sánchez,Parvohallopora cystataJiménez-Sánchez, andAostipora elongataJiménez-Sánchez. Univariate statistical analyses …
Overview of the Opportunity Mars Exploration Rover Mission to Meridiani Planum: Eagle Crater to Purgatory Ripple
2006
The Mars Exploration Rover Opportunity touched down at Meridiani Planum in January 2004 and since then has been conducting observations with the Athena science payload. The rover has traversed more than 5 km, carrying out the first outcrop-scale investigation of sedimentary rocks on Mars. The rocks of Meridiani Planum are sandstones formed by eolian and aqueous reworking of sand grains that are composed of mixed fine-grained siliciclastics and sulfates. The siliciclastic fraction was produced by chemical alteration of a precursor basalt. The sulfates are dominantly Mg-sulfates and also include Ca-sulfates and jarosite. The stratigraphic section observed to date is dominated by eolian bedfor…
In situ evidence for an ancient aqueous environment at Meridiani Planum, Mars.
2004
Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features include hematite-rich concretions and crystal-mold vugs. We interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history. The environmental conditions that they record include episodic inundation by shallow surface water, evaporation, and desiccation. The …