Boninites are unusual island arc volcanic rocks with high MgO (>9%), high Si0 2 (>55%) contents, and exceptionally low TiO 2 (<0.4%) contents. High MgO contents, MgO/(MgO + EFeO), Ni, Cr and Co contents indicate that boninites have equilibrated with mantle peridotite. Experimental petrologic studies and high Cr/(Cr + Al) in spinels in boninites suggest that they have separated from extremely re...

Anorthosites occur ubiquitously within the lunar crust at depths of 3-30 km in apparent confirmation of the Lunar Magma Ocean (LMO) hypothesis [1,5]. We will present recent chronological studies of anorthosites [2] that are relevant both to the LMO hypothesis and also to the lunar cataclysm hypothesis. Old (ca. 4.4 Ga) Sm-Nd ages have been determined for some Apollo 16 anorthosites, and primiti...

Introduction: The recently acquired meteorite Tissint is the first recognized fall of a depleted shergottite. Other such shergottites were found in the hot deserts (e.g., NWA 1195, Dhofar 019, DAG 476) or in the Antarctic cold desert (e.g., QUE 94201, Y980459) and, in many cases, have disturbed isotopic systematics due to terrestrial contamination [1-4]. Tissint represents the freshest sample o...

The metamorphic facies of the subsurface Precambrian of Alberta are charted for the first time as a contribution to the new tectonometamorphic map of the Canadian Shield. Inferences about facies are based primarily on petrographically determined mineral assemblages. A few P–T determinations from results of electron-microprobe analyses are available. The chronology of metamorphic events is based...

Various diffusion raodels can be applied to Rb-Sr systems in cooling rocks. It is argued that a closed-system diffusioncontrolled model, inw3lving local equilibrium along grain boundaries, is most appropriate for describing the exchange of Sr isotopes between minerals in a rock sample during cooling. A finite-difference numerical method is used to solve the diffusion and mass-balance equations....

Introduction: NWA 1068 is a 577g picritic shergottite found in the Moroccan Sahara in 2001[1]. The meteorite resembles several other picritic shergottites, e.g. EETA79001B, DaG476, SaU005 and Dho019, in major-element chemistry and mineralogy, but it differs significantly from these meteorites in REE distribution pattern. It has a slightly LREE-depleted pattern commonly shared by some olivine-fr...

The Limerick Igneous Suite (LIS) in County Limerick, SW Ireland, contains two distinct basaltic igneous units: the Knockroe and Knockseefin, which are expressed as hypabyssal intrusions, porphyritic dykes, diatremes, lava flows, agglomerates tuffs. These units make up evolutionary trends: range from alkaline basalts to trachyandesites, Knockseefin basanites. U‒Pb dating of apatite establishes a...

Introduction: Many questions regarding the petrogenesis of mare basalts remain unresolved. Trace element and isotope geochemists tend to view the range of mare basalt compositional groups as independent primary magmas and develop mantle melting models to explain the compositional diversity [e.g. 1, 2, 3]. On the other hand, petrologists view the mare basalt suites as non-primary and suggest tha...