Search results for "Crust"

Petrology, geochronology, and tectonic implications of c . 500 Ma metamorphic and igneous rocks along the northern margin of the Central Asian Orogen…

2008

A significant portion of the continental crust of northern Eurasia is thought to have formed during the evolution of the Central Asian Orogenic Belt at the time of accretion of continental terranes and island arcs. Records of this event are well preserved within the Siberian craton–Central Asian Orogenic Belt transition zone in Lake Baikal region, particularly in the Olkhon terrane. Our results establish granulite-facies conditions for peak metamorphism in the Olkhon terrane, and indicate that the granulites were derived from island arc mafic volcanic rocks and back-arc basin sediments. Sensitive high-resolution ion microprobe dating of metamorphic zircons from two mafic granulites yielded …

Geochemistry, zircon ages and whole-rock Nd isotopic systematics for Palaeoproterozoic A-type granitoids in the northern part of the Delhi belt, Raja…

2006

Determination of zircon ages as well as geochemical and Sm–Nd isotope systematics of granitoids in the Khetri Copper Belt of the Aravalli mountains, NW India, constrain the late Palaeoproterozoic crustal evolution of the Aravalli craton. The plutons are typical A-type within-plate granites, derived from melts generated in an extensional tectonic environment. They display REE and multi-element patterns characterized by steep LREE-enriched and almost flat HREE profiles and distinct negative anomalies for Sr, P and Ti. Initial εNd values range from −1.3 to −6.2 and correspond to crustal sources with mean crustal residence ages of 2.5 to 2.1 Ga. A lower mafic crustal anatectic origin is envisag…

Convergence of roles among peracarids in critical environments.

2011

A first snapshot of sandy-beach amphipod (Crustacea) assemblage in a Marine Protected Area, Favignana Island (central Mediterranean Sea)

2017

The aim of this study is to compile a preliminary first check-list of Amphipoda species from beaches of Favignana Island (Sicily, Italy), and contribute to the knowledge relating to the distribution of this taxon in the Mediterranean Sea. Five amphipod species, belonging to two families (Talitridae and Hyalidae), have been collect in the island. The supralittoral assemblage appears to contain three main biogeographical categories: Atlanto-Mediterranean species, Mediterranean endemic species and cosmopolitan species.

Food selection in Eucypris virens (Crustacea: Ostracoda) under experimental conditions

2007

Ostracods have long been studied by scientists because their fossil remnants provide a valuable tool for the reconstruction of past environmental changes, including climate change and anthropogenic eutrophication. Relatively little is known about the physiology, behaviour and reproductive ecology of recent forms. We argue that filling this gap in knowledge requires stable cultures that can be used in laboratory studies. Here we provide quantitative information on the food preference of the common non-marine ostracod Eucypris virens. Using an experimental device allowing a free choice of eight food items, including both auto- and heterotrophic organisms, observations were carried out on grou…

A respiratory hemocyanin from an insect.

2004

Insects possess an elaborate tracheal system that enables transport of gaseous oxygen from the atmosphere directly to the inner organs. Therefore, the presence of specialized oxygen-transport proteins in the circulatory system of insects has been considered generally unnecessary. Here, we show for the first time, to our knowledge, the presence of an ancestral and functional hemocyanin (Hc) in an insect. In the hemolymph of nymphs and adults of the stonefly Perla marginata , a hexameric Hc was identified, which consists of two distinct subunit types of 659 and 655 amino acids. P. marginata Hc displays cooperative oxygen binding with a moderately high oxygen affinity [(half-saturation pressu…

Gravity modelling of the lower crust in Sardinia (Italy)

1997

In this paper an example is given of an application of statistical techniques to the Bouguer anomalies analysis in order to design a simple crustal model using few a priori assumptions. All gravity measurements carried out in Sardinia have been collected and processed. The Bouguer anomalies have been calculated according to local density estimates. Spectral analysis of the Bouguer anomalies has been carried out along selected profiles in order to estimate the mean depth of the Moho discontinuity and that of an infracrustal discontinuity. The use of this technique inferred the presence of a discontinuity at a mean depth of ~ 28 km, interpreted as Moho and the likely presence of an infracrust…

Organotin(IV) derivatives with 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidine and their cytotoxic activities: The importance of being conformers

2014

Abstract The organotin(IV) compounds Me2SnCl2(dbtp)(1), Me2SnCl2(dbtp)2 (2), Et2SnCl2(dbtp) (3), Et2SnCl2(dbtp)2 (4), Et2SnCl2(dptp) (5), nBu2SnCl2(dbtp)2 (6), nBu2SnCl2(dptp) (7), Ph2SnCl2(dbtp) (8), Ph2SnCl2(EtOH)2(dptp)2 (9), where dbtp = 5,7-di-tert-butyl-1,2,4-triazolo[1,5-a]pyrimidine and dptp = 5,7-diphenyl-1,2,4-triazolo [1,5-a]pyrimidine, have been tested by MTT for their cytotoxic activity on three tumor cell lines, HepG2 (human hepatocellular carcinoma), HeLa (human cervix adenocarcinoma) and MCF-7 (human breast cancer). Except for 1 and 2, which were ineffective, all compounds significantly showed a dose-dependent anti-proliferative effect against the three cell lines. By calcul…

The formation of peak rings in large impact craters.

2016

The Chicxulub impact crater, known for its link to the demise of the dinosaurs, also provides an opportunity to study rocks from a large impact structure. Large impact craters have “peak rings” that define a complex crater morphology. Morgan et al. looked at rocks from a drilling expedition through the peak rings of the Chicxulub impact crater (see the Perspective by Barton). The drill cores have features consistent with a model that postulates that a single over-heightened central peak collapsed into the multiple-peak-ring structure. The validity of this model has implications for far-ranging subjects, from how giant impacts alter the climate on Earth to the morphology of crater-dominated …

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…