Oscar M. Lovera

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Perhaps the best known occurrence of an inverted metamorphic sequence is that found immediately beneath the Himalayan Main Central Thrust (MCT), generally thought to have been active during the Early Miocene. However, in situ 208Pb/ 232Th dating of monazite inclusions in garnet indicates that peak metamorphic recrystallization of the MCT footwall occurred(More)
Large deviations in ɛHf(T) from bulk silicate Earth seen in N4 Ga detrital zircons from Jack Hills, Western Australia, have been interpreted as reflecting a major differentiation of the silicate Earth at 4.4 to 4.5 Ga. We have expanded the characterization of Hf/Hf initial ratios (Hf ) in Hadean zircons by acquiring a further 116 laser ablation Lu–Hf(More)
decompression to achieve the same result appear to require extreme The Manaslu granite is the most studied of the dozen or so plutons conditions not permitted by available geological constraints. that make up the High Himalayan leucogranite belt. The inferred relationship of the Manaslu granite with important Himalayan tectonic structures has inspired(More)
We examine a database containing the results of Ar/Ar step-heating experiments performed on 194 basement K-feldspars to recover thermal history information. Qualitative examination of Ar/Ar systematics reveals that about half of the K-feldspars examined are sufficiently well-behaved to be suitable for thermal history analysis. Correlation algorithms are(More)
Combined U-Pb zircon and Ar/Ar sanidine data from volcanic rocks within or adjacent to the Geysers geothermal reservoir constrain the timing of episodic eruption events and the pre-eruptive magma history. Zircon U-Pb concordia intercept model ages (corrected for initial Th disequilibrium) decrease as predicted from stratigraphic and regional geological(More)
The Magdalena fan is an apparently beheaded submarine depocenter that has fi gured prominently in reconstructions of middle to late Miocene Pacifi c–North American plate interactions. The deposit accumulated rapidly at the base of the continental slope on top of newly formed oceanic crust of the Magdalena microplate from 14.5 to 13 Ma. Subduction of this(More)
Coesiteand diamond-bearing ultrahigh-pressure (UHP) metamorphic rocks represent continental materials that were once subducted to depths of >90 km. Identifying how these rocks were subsequently returned to Earth’s surface has been a major challenge. Opinions on this matter vary widely, ranging from vertical extrusion of a coherent continental slab to(More)
Over 400 ion microprobe U-Pb isotopic ages measured for zircons extracted from 24 geothermal wells that penetrate the Geysers Plutonic complex (GPC) allow us to conclude that the entire known extent of the GPC crystallized during the early Pleistocene. Nine samples of the microgranite porphyry that forms the shallow cupola (100–1,500 m below sea-level,(More)
a Department of Earth and Space Sciences, University of California, Los Angeles, 3806 Geology, Los Angeles, CA 90095, USA b Department of Earth and Space Sciences and the Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA c Department of Geological & Environmental Sciences, Stanford University,(More)