Search results for "Lithophile"
showing 4 items of 4 documents
An anorogenic pulse in a typical orogenic setting: The geochemical and geochronological record in the East Serbian latest Cretaceous to Palaeocene al…
2013
Abstract This study focuses on the East Serbian latest Cretaceous to Palaeocene Mafic Alkaline Rocks (hereafter, ES-MAR). This alkaline magmatism developed along the Eurasian border after the closure of the Mesozoic Tethys in the Balkan sector. Olivine(± clinopyroxene)-phyric and olivine- and nepheline-normative basanite, tephrite and theralite rocks are studied using Ar/Ar ages and major elements, trace elements and Sr–Nd–Pb isotopes. The ES-MAR are geochemically similar to other alkaline rocks of the Circum-Mediterranean Anorogenic Cenozoic Igneous (CiMACI) province, showing elevated contents of high field strength elements (HFSE) (e.g., Nb = 50–100 ppm) and high HFSE/LILE (large ion lith…
Highly siderophile elements (PGE, Re and Au) in mantle xenoliths from the West Eifel volcanic field (Germany)
2003
Abstract Mantle peridotite xenoliths ranging in modal composition between fertile lherzolites and modally metasomatized harzburgites, and magmatic pyroxenite xenoliths from the West Eifel and Vogelsberg volcanic fields (Germany) have been analyzed for their whole rock major and minor elements, six platinum-group elements PGE (PGE: Os, Ir, Pt, Ru, Rh, Pd), Re and Au, rare earth elements (REE), and several other trace elements (e.g., As, Ta). The bulk rock Ir concentrations range from 0.23 to 9.07 ng/g (total PGE contents range between 43.2 ng/g), exceeding the range previously found in mantle rocks. Two pyroxenite samples show large variabilities in their PGE concentrations, with Ir contents…
Ultrapotassic volcanism from the waning stage of the Neotethyan subduction: a key study from the Izmir-Ankara-Erzincan suture belt, central northern …
2016
Upper Cretaceous volcano-sedimentary successions in the Central Pontides of Turkey, related to the closure of the Tethys Ocean, include a variety of alkaline ultrapotassic igneous rocks that have been classified as leucititic, lamprophyric and trachytic based on their mineral paragenesis. Although the ultrapotassic rocks display a range of K 2 O contents (0·9–8·4 wt %) that may partly reflect alteration processes, they display subduction-related trace element signatures characterized by significant enrichment of large ion lithophile elements and light rare earth elements relative to high field strength elements and heavy rare earth elements and depletion of Nb and Ta. However, their initial…
The analcime problem and its impact on the geochemistry of ultrapotassic rocks from Serbia
2004
AbstractTertiary ultrapotassic volcanic rocks from Serbia occasionally display low levels of K2O and K2O/ Na2O. In these rocks, analcime regularly appears as pseudomorphs after pre-existing leucite microphenocrysts. The process ofleucite transformation in Serbian ultrapotassic rocks is very thorough: fresh leucite survives only in ugandites from the Koritnik lava flows as well as in rare inclusions in Cpx. This paper focuses on the impact of ‘analcimization’ on the mineralogy and geochemistry ofthe Serbian ultrapotassic rocks, using the samples where leucite survived as a monitor for the process.Analcimization has had a great impact on the geochemistry of the rocks, but affects only a restr…