Search results for "Lithology"
showing 10 items of 61 documents
A laboratory cave for the study of wall degradation in rock art caves : an implementation in the Vézère area
2013
The aim of this proposal is to present an original approach to the study and preservation of rock art caves. A multidisciplinary study of cave wall alteration will be performed to understand the impact of environmental context on the evolution of wall surfaces. The approach involves the choice of a cave with characteristics similar to painted caves in the studied area (Vézère Valley in Dordogne, France): e.g., cave wall alteration, lithology, morphology, etc. This selected cave is intended to become a laboratory cave, monitored for the acquisition of chemical, physical and biological environmental data on bedrock, air and fluids along with their characteristics. A cave without art or archae…
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…
Worldwide distribution of continental rock lithology: Implications for the atmospheric/soil CO2uptake by continental weathering and alkalinity river …
2003
[1] The silicate rock weathering followed by the formation of carbonate rocks in the ocean, transfers CO2 from the atmosphere to the lithosphere. This CO2 uptake plays a major role in the regulation of atmospheric CO2 concentrations at the geologic timescale and is mainly controlled by the chemical properties of rocks. This leads us to develop the first world lithological map with a grid resolution of 1° × 1°. This paper analyzes the spatial distribution of the six main rock types by latitude, continents, and ocean drainage basins and for 49 large river basins. Coupling our digital map with the GEM-CO2 model, we have also calculated the amount of atmospheric/soil CO2 consumed by rock weathe…
Mixing relationships and the effects of secondary alteration in the Wishstone and Watchtower Classes of Husband Hill, Gusev Crater, Mars
2006
[1] The Wishstone and Watchtower Class rocks on Husband Hill preserve evidence for a geochemical relationship consistent with two-component mixing between a high Al 2 O 3 , TiO 2 , CaO, Na 2 O, P 2 O 5 end-member and a second end-member enriched in the elements MgO, Zn, S, Br, and Cl. The first end-member appears to be reasonably well represented by rocks of the Wishstone Class, while the second end-member is consistent with a chemical component, not represented by any lithology encountered by Spirit. The Watchtower Class appears to be an intermediate in the mixture. The concentration of the redox sensitive elements Fe and Mn display no systematic variation between rock classes, and the Fe-…
The role of the diagnostic areas in the assessment of landslide susceptibility models: a test in the sicilian chain
2011
Abstract The aim of the research was to verify and compare the predictive power of different diagnostic areas in assessing landslide susceptibility with a multivariate approach. Scarps, landslide areas (the union between scarp and accumulation zones) and areas uphill from crowns, for rotational slides, source or scarp areas and landslide areas, for flows, have been tested. A multivariate approach was applied to assess the landslide susceptibility on the basis of three selected conditioning factors (lithology, slope angle, and topographic wetness index), which were combined in a Unique Condition Unit (UCU) layer. By intersecting the UCU layer with the vector layer of the diagnostic areas, la…
The Spirit Rover's Athena science investigation at Gusev Crater, Mars.
2004
The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.
Fabric control on strain and rupture of heterogeneous shale samples by using a non-conventional mechanical test
2004
Abstract This work was a part of the preliminary stage of the ANDRA project on a deep-seated research laboratory for the feasibility study of long-term radioactive waste storage in the Callovo–Oxfordian argillites of the Eastern part of the Paris Basin. These rocks are bedded, their density is about 2.4, and they contain an average of 30% carbonates and 25% quartz. Thick (5 mm) sections from cores were put through a non-conventional device called CGI testcell (CGI: Centre de Geologie de l'Ingenieur, i.e. Engineering Geology Centre). The aim of this versatile device is to achieve plane deformation tests under compressive uniaxial loading together with controlled temperature and humidity cond…
Impact of hydrologically driven hillslope erosion and landslide occurrence on soil organic carbon dynamics in tropical watersheds
2016
The dynamics of soil organic carbon (SOC) in tropical forests play an important role in the global carbon (C) cycle. Past attempts to quantify the net C exchange with the atmosphere in regional and global budgets do not systematically account for dynamic feedbacks among linked hydrological, geomorphological, and biogeochemical processes, which control the fate of SOC. Here we quantify effects of geomorphic perturbations on SOC oxidation and accumulation in two adjacent wet tropical forest watersheds underlain by contrasting lithology (volcaniclastic rock and quartz diorite) in the Luquillo Critical Zone Observatory. This study uses the spatially-explicit and physically-based model of SOC dy…
Case studies - Research and technological solutions to prevent sand production in the gas wells from the Getic Depression
2021
A frequent challenge encountered in the exploitation of mature gas fields located in the Getic Depression is sand production. Causes of sand production are mainly related to degree of rock consolidation, lithology, increasing water production and production rates. The effects of sand production are multiple such us low productivity of the gas wells, accumulation into the surface equipment, erosion of downhole and surface equipment, plugging the perforation zone and casing damage. The current paper will address the sand production- challenges and new perspectives in remedial work of wells which are producing from gas reservoirs located in Getic Depression. The article presents through some c…
A snapshot of the transition from monogenetic volcanoes to composite volcanoes: Case study on the Wulanhada Volcanic Field (northern China)
2022
The transition processes from monogenetic volcanoes to composite volcanoes are poorly understood. The Late Pleistocene to Holocene intraplate monogenetic Wulanhada Volcanic Field (WVF) in northern China provides a snapshot of such a transition. Here we present petrographic observations, mineral chemistry, bulk rock major and trace element data, thermobarometry, and a partial melting model for the WVF to evaluate the lithology and partial melting degree of the mantle source, the crystallization conditions, and pre-eruptive magmatic processes occurring within the magma plumbing system. The far-field effect of India–Eurasia collision resulted in a relatively high degree (10 %–20 %) of partial …