To investigate the process and chemistry of mineral reaction zone formation, we conducted detailed petrographic observations chemical analysis rocks minerals spinel lherzolite xenoliths from basanites Tumusun volcano (Baikal Rift Zone). The zones gradually disappear contact toward center xenoliths. influence basanite melt on major trace element composition secondary is notable only at a distanc...

The occurrence of volcanic basanite cobbles in Pleistocene terraces at Galloway and the upper Clutha valley Central Otago, an area devoid known edifices, has implications for Cenozoic intraplate volcanism drainage region. We present petrographic, mineralogical, whole rock geochemical Sr-Nd-Pb isotopic data, as well 39Ar-40Ar date 24.4 ± 0.06 Ma, together with mineral analyses enclosed peridotit...

Abstract Mason Spur is a deeply eroded Middle Miocene to Pleistocene (c. 13 0.37 Ma) volcanic complex in southern Victoria Land, within the West Antarctic Rift System (WARS). The oldest rocks include large volume of trachyte ignimbrites that provided abundant detritus recovered McMurdo Sound drill cores. together with early-formed intrusions were strongly deformed during substantial caldera col...

High-spatial-resolution (230Th)/(238U) disequilibrium dating reveals rapid zircon crystallization prior to the 12,900 yr B.P. Laacher See (Germany) phonolite eruption. Zircons from Lower Laacher See tephra (LLST) and syenitic subvolcanic nodules share REE and low U/Th characteristics and define an isochron age of 17.1 1.3 ka (1 ). Zircons also show higher initial (Th)/(Th)0 and oxygen isotopic ...

Abstract We present a new experimental dataset for reaction experiments between natural amphibole-clinopyroxene metasomes (hornblendite) and synthetic lherzolite that produced Na-rich alkaline melts. Experiments were conducted at 1, 3 4 GPa 1000–1300 °C. The generated melts range from foidite over basanite to phonotephrite. At 1 1000 1100 °C amphibole decompression-breakdown products generate p...