The presence of diamonds of Archaean age within the cratonic lithosphere is surprising because their formation implies a cool early mantle lithosphere despite the early Earth's hotter state. There remains a widely (albeit not exclusively) held concept that the prevailing geothermal gradient within Archaean cratons was not much different from today....
Published in Frontiers in Earth Science
The occurrence of mantle-derived peridotite xenoliths in phonolitic melts is a rare phenomenon, and is commonly ascribed to a mantle origin of the phonolite. The alternative possibility, that xenoliths are transported into evolving phonolite melts by mafic magmas, has received little attention. A unique tephriphonolite lava with phonolitic groundma...
Published in Petrology
bstractThe mineral zoning of corundum-bearing rocks of the Belomorian mobile belt, whose genesis remains controversial, has been studied at one of the typical occurrences: Khitoostrov. Based on the estimates of the P–T parameters of the formation of corundum-bearing rocks by the multiequilibrium thermobarometry method, pseudosections were construct...
Knowledge of crustal architecture, and the distribution of rock types within, did not by itself provide geologists unambiguous evidence of its evolution. It was not until the advent of modern geochemical and petrologic methods in the 1960s that the mechanisms and timescales of continental crustal evolution began to be delimited. Chapter 1 of this t...
Systematic variations in the crystal cargo and whole-rock isotopic compositions of mantle-derived basalts in the intraplate Dunedin Volcano (New Zealand) indicate the influence of a complex mantle-to-crust polybaric plumbing system. Basaltic rocks define a compositional spectrum from low-alkali basalts through mid-alkali basalts to high-alkali basa...
Published in Journal of Earth System Science
Lamprophyric (lamproitic) diatremes in Chompolo field, NE Aldan shield, Siberia dated 132 Ma contain abundant mantle xenocrysts studied by EPMA and LA-ICP-MS. The deepest rocks ~6.5 GPa determined with thermobarometry are phlogopite eclogites. Thermobarometry on pyrope garnets, Cr-diopside and chromites yield a relatively low-temperature geotherm o...
Published in Geotectonics
AbstractPoly-deformed late-Proterozoic metamorphic domains covering Um Ashira area at the western segment of Wadi Allaqi shear zone, South Eastern Desert of Egypt, show evidences of inverted Barrovian metamorphism. They exhibit four metamorphic zonal patterns, arranging progressively from chlorite, biotite, garnet, to sillimanite zones. The higher ...
Published in Frontiers in Earth Science
This paper briefly reviews the magmatic manifestations of volcanic arcs and aspects of how such magmas form. Common concepts about “how subduction zones work” are reassessed—with particular emphasis on the atypical Cascades volcanic arc. This arc is associated with one of the warmest modern subduction zones, with accelerated slab dehydration and lo...
Published in Frontiers in Earth Science
The Popocatépetl Volcanic Complex (PVC) is an active arc volcano located in central Mexico, 70 km southeast of Mexico City. Current models of the PVC’s plumbing system and magma petrogenesis are largely based on studies of isolated Plinian eruptions over the past 23.5 ka and present-day Vulcanian activity, while voluminous interplinian effusive sum...
Published in American Mineralogist
We have examined the suitability of a quartz-inclusions-in-epidote (qtz-in-ep) mineral barometer to better constrain P-T histories of epidote-bearing lithologies. Theoretical calculations applying an isotropic elastic model suggest that the qtz-in-ep barometer exhibits minimal temperature dependence, and thus, offers the potential to constrain grow...
