Paul R. Craddock

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We present new high precision iron isotope data (dFe vs. IRMM-014 in per mil) for four groups of achondrites: one lunar meteorite, 11 martian meteorites, 32 howardite–eucrite–diogenite meteorites (HEDs), and eight angrites. Angrite meteorites are the only planetary materials, other than Earth/Moon system, significantly enriched in the heavy isotopes of Fe(More)
High-precision iron isotopic compositions for Fe-bearing geological reference materials and chondrites with a wide range of matrices (e.g., silicates, oxides, organic-bearing materials) are reported. This comprehensive data set should serve as a reference for iron isotopic studies across a range of geological and biological disciplines for both quality(More)
The causes of some stable isotopic variations in felsic rocks are not well understood. In particular, the origin of the heavy Fe isotopic compositions (i.e., high dFe values, deviation in& of the Fe/Fe ratio relative to IRMM-014) of granites with SiO2 > 70 wt.% compared with less silicic rocks is still debated. It has been interpreted to reflect isotopic(More)
Terrestrial oceanic and continental basalts are enriched by approximately þ0.1% in Fe/Fe ratio relative to primitive, undifferentiated meteorites (chondrites). The dFe values of terrestrial basalts are also distinct from those of basalts from Mars and asteroid Vesta, which have chondritic Fe isotopic compositions. The processes responsible for the isotopic(More)
Oxygen and iron isotope analyses of low-Ti and high-Timare basalts are presented to constrain their petrogenesis and to assess stable isotope variations within lunar mantle sources. An internally-consistent dataset of oxygen isotope compositions of mare basalts encompasses five types of low-Ti basalts from the Apollo 12 and 15 missions and eight types of(More)
This article introduces a new model of Pavlovian conditioning, attention as an acquisition and performance variable (AAPV), which, like several other so-called attentional models, emphasizes the role of variation of cue salience, together with associative strength, in accounting for conditioning phenomena. AAPV is primarily (but not exclusively) a(More)
Prior research, using two- and three-dimensional environments, has found that when both human and nonhuman animals independently acquire two associations between landmarks with a common landmark (e.g., LM1-LM2 and LM2-LM3), each with its own spatial relationship, they behave as if the two unique LMs have a known spatial relationship despite their never(More)
PERIDOTITES, AND EOARCHEAN MAGMAS. N. Dauphas, P.R. Craddock, V. Bennett, and D. Ohnenstetter, Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago (dauphas@uchicago.edu), California Institute of Technology, Division of Geological & Planetary Sciences, Research School of Earth Sciences, Department(More)
The present study demonstrates the contribution of spatial contiguity in the formation of associations between two neutral stimuli. Using human participants, we used visual conditioned stimuli (CSs) in a sensory preconditioning design in which simultaneous CS2-CS1 pairings and CS4-CS3 pairings were interspersed during Phase 1, followed by sequential CS1-US+(More)