Search results for "Rocks"

Geochemical characteristics of Cretaceous carbonatites from Angola

1999

Abstract The Early Cretaceous (138–130 Ma) carbonatites and associated alkaline rocks of Angola belong to the Parana-Angola-Etendeka Province and occur as ring complexes and other central-type intrusions along northeast trending tectonic lineaments, parallel to the trend of coeval Namibian alkaline complexes. Most of the Angolan carbonatite-alkaline bodies are located along the apical part of the Mocamedes Arch, a structure representing the African counterpart of the Ponta Grossa Arch in southern Brazil, where several alkaline-carbonatite complexes were also emplaced in the Early Cretaceous. Geochemical and isotopic (C, 0, Sr and Nd) characteristics determined for five carbonatitic occurren…

Permeability and its effect on the utilization of geothermal energy

2008

The marble field of Custonaci (Sicily-Italy)

2008

Volatile dilution during magma injections and implications for volcano explosivity

2016

Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Here we examine plagioclase phenocrysts in pumice from the 2014 Plinian eruption of Kelud (Indonesia) that record the progressive capture of small melt inclusions within concentric growth zones during crystallization inside a magma reservoir. High-spatial-resolution Raman spectroscopic measurements reveal the concentration of dissolved H2O within the melt inclusions, and provide insights into melt-volatile behavior at the single crystal…

Importance des variations latérales discrètes dans les apports détritiques, observées dans des faciès de rampe sédimentaire riches en matière organiq…

2017

17 pages; International audience; We studied a potential petroleum source rock deposited in a clastic-dominated ramp environment: the Argiles de Châtillon Formation (Kimmeridgian-Tithonian, Boulonnais area, northern France). The formation was deposited along a proximal-distal gradient on this ramp affected by synsedimentary fault movements. A sedimentological, mineralogical and geochemical study was conducted to decipher the distribution patterns of sedimentary parameters along such a depth increase over the ramp. It comes out that smectite distribution unexpectedly mimics the lateral depth evolution despite the good floatability of the mineral. It is also observed that the Argiles de Châti…

Insights into the compositional evolution of crustal magmatic systems from coupled petrological-geodynamical models

2020

Funding was provided by the VAMOS Research Center, University of Mainz (Germany) and by the ERC Consolidator Grant MAGMA (project #771143). The evolution of crustal magmatic systems is incompletely understood, as most studies are limited either by their temporal or spatial resolution. Exposed plutonic rocks represent the final stage of a long-term evolution punctuated by several magmatic events with different chemistry and generated under different mechanical conditions. Although the final state can be easily described, the nature of each magmatic pulse is more difficult to retrieve. This study presents a new method to investigate the compositional evolution of plutonic systems while consid…

A risk assessment proposal for underground cavities in Hard Soils-Soft Rocks

2018

Abstract Underground calcarenite quarries in Marsala (Sicily) have been involved in a number of collapses that have, seriously damaged numerous buildings. The stability conditions were therefore examined in order to assess risk conditions within the historical centre of the town and the surrounding areas, which are subject to urban expansion. Starting with an extensive collection of historical information, the research was carried out through surveys of the cavities, systematic sampling of material, petrographic analysis and geotechnical testing. The results of laboratory tests and in situ investigations provided a geotechnical characterization of both the intact material and the rock mass.…

Thermal and structural modeling of the Scillato wedge-top basin source-to-sink system. Insights into the Sicilian fold-and-thrust belt evolution (Ita…

2019

AbstractTemperature-dependent clay mineral assemblages, vitrinite reflectance, and one-dimensional (1-D) thermal and three-dimensional (3-D) geological modeling of a Neogene wedge-top basin in the Sicilian fold-and-thrust belt and its pre-orogenic substratum allowed us to: (1) define the burial history of the sedimentary succession filling the wedge-top basin and its substratum, (2) reconstruct the wedge-top basin geometry, depocenter migration, and sediment provenance through time in the framework of a source-to-sink system, and (3) shed new light into the kinematic evolution of the Apennine-Maghrebian fold-and-thrust belt.The pre-orogenic substratum of the Scillato basin shows an increase…

Natural radioactivity in the Alte Madonie Mounts (Sicily, Italy)

2009

With the collaboration of geology experts, we have taken 45 samples of selected soils and rocks. All samples were powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement so as to ensure that radioactive equilibrium between 226Ra and 214Bi has been reached. Mineralogical and chemical features of the samples were determined by XRD and XRF analysis, instead Gamma ray spectrometric analysis was used in order to quantify radioactivity concentrations. The average values of concentrations of 214Bi, 228Ac and 40K are respectively 30, 19 and 258 Bq/kg while the greatest values were 134, 59 and 748 Bq/kg. A linear relationship exists between 214Bi, 228Ac and 40K activitie…

Characterisation and origin of hydrothermal waters at São Miguel (Azores) inferred by chemical and isotopic composition

2017

Abstract This study focuses on the characterisation and origin of hydrothermal waters discharging from three main active volcanoes (Furnas, Fogo and Sete Cidades) at Sao Miguel, where 33 water with temperatures ranging between 13 and 97 °C, and 5 precipitate samples were collected. The developed conceptual model for this active hydrothermal system reveals that all waters can be classified by Na-HCO 3 , Na-Cl and Na-SO 4 types and are of meteoric origin. This is confirmed by the stable hydrogen and oxygen isotope data that are positioned close to the local meteoric water line (− 4.1‰ ≤ δ 18 O H2O  ≤ 5.2‰; − 17.6‰ ≤ δD H2O  ≤ 20.4‰), except for the Na-Cl type water at Ferraria (Sete Cidades a…