0000000000299110
AUTHOR
Marina Lazarov
Mafic alkaline metasomatism in the lithosphere underneath East Serbia: evidence from the study of xenoliths and the host alkali basalts
Effects of mafic alkaline metasomatism have been investigated by a combined study of the East Serbian mantle xenoliths and their host alkaline rocks. Fertile xenoliths and tiny mineral assemblages found in depleted xenoliths have been investigated. Fertile lithologies are represented by clinopyroxene (cpx)-rich lherzolite and spinel (sp)-rich olivine websterite containing Ti-Alrich Cr-augite, Fe-rich olivine, Fe-Al-rich orthopyroxene and Al-rich spinel. Depleted xenoliths, which are the predominant lithology in the suite of East Serbian xenoliths, are harzburgite, cpxpoor lherzolite and rare Mg-rich dunite. They contain small-scale assemblages occurring as pocket-like, symplectitic or irreg…
Sulfide enrichment at an oceanic crust-mantle transition zone: Kane Megamullion (23°N, MAR)
Abstract The Kane Megamullion oceanic core complex located along the Mid-Atlantic Ridge (23°30′N, 45°20′W) exposes lower crust and upper mantle directly on the ocean floor. We studied chalcophile elements and sulfides in the ultramafic and mafic rocks of the crust-mantle transition and the mantle underneath. We determined mineralogical and elemental composition and the Cu isotope composition of the respective sulfides along with the mineralogical and elemental composition of the respective serpentines. The rocks of the crust-mantle transition zone (i.e., plagioclase harzburgite, peridotite-gabbro contacts, and dunite) overlaid by troctolites are by one order of magnitude enriched in several…
Geodynamic significance of ultramafic xenoliths from Eastern Serbia: Relics of sub-arc oceanic mantle?
A suite of highly depleted peridotite xenoliths in East Serbian Palaeogene basanites represents the lithospheric mantle beneath the Balkan Peninsula. The xenoliths are harzburgites, clinopyroxene-poor lherzolites and rare dunites. They contain mostly 91), high Cr# in spinel (mostly 0.5–0.7), and by distinctively low Al2O3 contents in orthopyroxene (mostly 1–2 wt.%). They have experienced some mantle metasomatism which has slightly obscured their original composition. Nevertheless, the general characteristics of the xenoliths imply a composition which is significantly more depleted than most non-cratonic sub-continental mantle xenolith suites, as well as orogenic peridotites and abyssal peri…
Modification of the subcontinental mantle beneath East Serbia: Evidence from orthopyroxene-rich xenoliths
Orthopyroxene-rich olivine websterite xenoliths (OWB2) in Palaeogene basanites in East Serbia are mostly composed of tabular low-Al2O3 orthopyroxene (> 70 vol.%, Mg# 85–87) containing tiny Cr spinel inclusions. Orthopyroxene shows a slightly U-shaped primitive mantle-normalized trace element pattern with strong peaks at U and Pb, similar to that of orthopyroxene from normal regional peridotitic mantle. In between the orthopyroxenes are interstitial spaces composed of partially altered olivine (Mg# 85–87), clinopyroxene, Ti-rich spinel, Mg-bearing calcite, K-feldspar, apatite, ilmenite and relicts of a hydrous mineral. Clinopyroxene appears as selvages around orthopyroxene and as coarser euh…