[1] Pyroxenes are useful indicators of igneous processes and may be identified in geologic materials in the laboratory or remotely through the use of spectroscopic analysis. Studies of the thermal infrared (vibrational) spectra of many compositions in the pyroxene solid solution series (quadrilateral orthopyroxene and clinopyroxene, and some nonquadrilateral compositions) have shown that spectr...

An ion probe study of trace elements in Mg-rich clinopyroxene phenocrysts in primitive Aleutian lavas provides constraints on the genesis of Aleutian adakites, and possible insights into the source of common Aleutian magmas. Clinopyroxene (cpx) phenocrysts in the primitive adakites have high Sr and Nd=Yb compared to cpx in Aleutian basalts. In the adakites, Sr and Nd=Yb are highest for high Mg#...

REE (LREE) into the glass with respect to clinopyroxene, but the A group of chrome-spinel peridotite upper-mantle xenoliths from the reverse for Sr and Y, in both mica-bearing and mica-free parageneses. Lashaine volcano, northern Tanzania, differs from other xenoliths In a mica-bearing melt pocket, Rb and Ba partition preferentially at this locality in containing glassy melt pockets. Modal, min...

[1] Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of B and Li in serpentinized peridotites from the Feather River Ophiolite (California) indicates that B is enriched in serpentine minerals compared to the whole-rock and less altered olivine grains, while Li in serpentine is depleted or comparable to whole-rock Li. The high B contents of serpentine minerals cor...

The Cenozoic volcanic rocks of Ross Island and vicinity, Antarctica, are surface flows, tuffs, breccias, and small intrusives. The prominent rock is basanitoid. Alkali-basalt magma reached the surface over an appreciable length of time and was differentiated to produce a rock series: basanitoid -. trachybasalt -, phonolite. The alkalic, silica-undersaturated rocks are part of a larger petrologi...

Introduction: Knowledge of how crystals grow is of fundamental importance for interpreting textures observed in meteorites. However, data on crystal growth of rock-forming silicates for a very small degree of undercooling (< 1°C) are extremely rare. Recently [1], it was demonstrated that these very small degrees of undercooling could be experimentally approached by studying the kinetic of Oswal...

We present the results of melting experiments on a moderately depleted peridotite composition (DMM1) at 10 kbar and 1250±1390 C. Specially designed experiments demonstrate that liquids extracted into aggregates of vitreous carbon spheres maintained chemical contact with the bulk charge down to melt fractions of 0 02±0 04 and approached equilibrium closely. With increasing melt fraction, SiO2, F...

The Hapaimamo flow contains xenoliths of gabbronorites, troctolites, dunites, websterites and periodotites. Composition of cumulate olivines ranges from Fo78-86, clinopyroxenes ranges from En47-53Wo37-40Fs8-12, and orthopyroxenes ranges from En71-83Wo2-5Fs13-25. Most xenoliths display an intergranular, subpoikilitic or poikilitic texture. Petrologic and compositional information point towards a...

We have determined the major and trace element compositions of 176 individual microtektites/ spherules from the Australasian, Ivory Coast, and North American microtektite and clinopyroxene-bearing (cpx) spherule layers. Trace element contents for up to 30 trace elements were determined by instrumental neutron activation analysis (INAA), and major element compositions were determined using energ...