P.K. Harvey

University of Nottingham

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M. A. Lovell

University of Pittsburgh

T. S. Brewer

University of Leicester

Philippe Pézard

Géosciences Montpellier

P. Jackson

University of Adelaide

Brian P. Atkin

University of Nottingham

C.C. Ferguson

University of Missouri–Kansas City

Lovell

University of Leicester

Sarah Haggas

University of Leicester

R. C. Flint

Loughborough University

C.G. Williams

European Organization for Nuclear Research

Cooperative Institutions

University of Leicester

University of Nottingham

British Geological Survey

Massachusetts Institute of Technology

Centre National de la Recherche Scientifique

Columbia University

Lamont-Doherty Earth Observatory

Université de Montpellier

Institut des Sciences de la Terre

Géosciences Montpellier

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Chemical Stratigraphy of Boreholes in the Izu-Bonin Arc from In Situ Nuclear Measurements

Proceedings of the Ocean Drilling Program. Scientific results (1992)

M. A. Lovell Philippe Pézard P.K. Harvey

In situ nuclear measurements were made in open-hole sections of Ocean Drilling Program Holes 792E and 793B.They provide quantitative estimates of a limited range of formation elements.A comparison of core and geochemical log data indicates reasonable agreements between the two.Limited analyses of a wide range of core samples indicate that although the chalk and nannofossil-rich silts are distinct, the admixture of sands, clays, and volcanogenic debris provides a range of homogeneous sediment compositions.The chemical homogeneity does not allow detailed distinct zoning on a simple chemical basis.Statistical analysis of the log data, however, reveals distinct and recognizable patterns that enable a chemostratigraphy to be derived for both sites.This chemostratigraphy is in agreement with the shipboard-derived lithologic units.It reveals considerable detail that may act as the focus for further evaluation.

Chemostratigraphy

Lithology

10.2973/odp.proc.sr.126.161.1992

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Citations (3)

Image-guided neural activity manipulation with a paramagnetic drug

Nature Communications (2020)

Sarah Bricault Ali Barandov P.K. Harvey Elizabeth DeTienne Aviad Hai

Abstract Targeted manipulations of neural activity are essential approaches in neuroscience and neurology, but monitoring such procedures in the living brain remains a significant challenge. Here we introduce a paramagnetic analog of the drug muscimol that enables targeted neural inactivation to be performed with feedback from magnetic resonance imaging. We validate pharmacological properties of the compound in vitro, and show that its distribution in vivo reliably predicts perturbations to brain activity.

Neural Activity

10.1038/s41467-019-13933-5

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Citations (14)

The estimation of modal mineralogy: a problem of accuracy in core-log calibration

Geological Society London Special Publications (1998)

P.K. Harvey T. S. Brewer M. A. Lovell Sandy Kerr

Abstract In the case study described here the quantitative modal mineralogy of a number of core samples was determined with the objective of using these modes to calibrate geochemical logs. Modal estimates were obtained for the core samples by quantitative X-ray diffraction, infrared spectroscopy, point counting of thin sections, and indirectly by calculation from a complete chemical analysis of the samples. In the case of calculated modes, three different algorithms were applied. A by-product of this particularly complete dataset is the possibility of evaluating the most accurate method of modal analysis, and although no certain conclusion is reached on this point the analysis of these data does demonstrate the difficulty of obtaining accurate modal estimates. The core samples, taken at regular intervals through a sand, sandy-shale sequence, capped by a carbonate unit, have a mineralogy which, although dominated by quartz, includes feldspars, carbonates, and clays (illite, kaolinite) together with minor phases. There was generally good agreement between methods in the estimation of quartz, total carbonate, albite, kaolinite, total clay and pyrite. The results for illite and K-feldspar were poor, a reflection of their relatively low concentrations (<10%), and problems of compositional co-linearity in the calculated modes.

10.1144/gsl.sp.1998.136.01.04

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Citations (6)

Spherically arranged inclusions in post-tectonic garnet porphyroblasts

Mineralogical Magazine (1973)

P.K. Harvey C.C. Ferguson

Summary Garnet porphyroblasts, containing elongate ilmenite inclusions arranged in an essentially spherical pattern, are described. The garnets are post-tectonic, and the inclusion pattern is the result of deformation and simultaneous replacement of the matrix by the growing porphyroblast.

Ilmenite

Matrix (chemical analysis)

10.1180/minmag.1973.039.301.13

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Citations (10)

The geochemistry of residual soils as an aid to geological mapping: A statistical approach

Journal of Geochemical Exploration (1987)

A. Shepherd P.K. Harvey R.C. Leake

Univariate

Identification

Geologic map

Ultramafic rock

10.1016/0375-6742(87)90084-7

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Citations (14)

Borehole Televiewer Data Analysis of Hole 504B from Legs 137 and 140

Anton Krammer Philippe Pézard P.K. Harvey Kerstin Fuchs

Hole 504B, about 200 km south of the Costa Rica Rift in the eastern equatorial Pacific, has been drilled over a succession of Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) legs to a total depth of 2000.4 meters below seafloor (mbsf).Borehole televiewer (BHTV) measurements were recorded over the intervals 275-497 mbsf on Leg 137, and 1497-1715 mbsf and 1868-1990 mbsf on Leg 140.Detailed investigation of the BHTV data revealed stress-induced wellbore breakouts in all depth intervals with variable occurrence.The statistical analysis of the wellbore breakouts shows that the orientation of the maximum horizontal stress (S Hmax ) varies from N53°E ± 28° in the interval 410-490 mbsf, to N21 °E ± 35° in the interval 1497-1715 mbsf, and N82°E ± 38 in the interval 1868-1990 mbsf.Whereas the intermediate depth interval shows a mean azimuth that is consistent with previous observations from borehole breakout analysis between 700 and 1500 mbsf, the upperand lowermost breakout intervals are rotated clockwise by 22° and 61°, respectively.As none of the observed intersecting structures correlates with the observed rotation ofS Hmwc , it is assumed that the rotation is affected by non-intersecting structures or structures beyond the wellbore head.The onset of the breakout interval from 410 to 490 mbsf correlates well with the Layer 2A/2B boundary and corresponds to a seismic anisotropy observed in the upper 500 m of the crust.For breakouts to occur in shallow depths, high S Hma jS hmin ratios are required or rock strengths must locally vary (to values

Breakout

Seafloor Spreading

10.2973/odp.proc.sr.137140.034.1995

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Citations (3)

Preliminary geochemical results from DSDP/ODP Hole 504B: a comparison of core and log data

Geological Society London Special Publications (1990)

T. S. Brewer M. A. Lovell P.K. Harvey R. Pelling Brian P. Atkin

Abstract DSDP/ODP Hole 504B, located in the Eastern Equatorial Pacific in 5.9 Ma old crust, penetrates both basaltic pillows and dykes down to a depth of 1562.1 m below the sea floor. Core recovery is poor, averaging 230ut falling to a 12% average in the deepest sections. Geochemical logs give a continuous measure of elemental (Si, Ca, Fe, S, Ti, Gd, H, Cl, K, Th, U) abundances. Correlation between laboratory (XRF) geochemical data and log data is difficult because of the lack of accurate depth information for the cores. Pattern recognition techniques are of little help for locating sample depths in the uniform basaltic lithologies. Non-hierarchical clustering techniques prove the existence of relationships between core descriptions and gross geochemical variations; major lithostratigraphic zones are readily identified from the log-derived data.

10.1144/gsl.sp.1990.048.01.16

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Citations (8)

Evidence for textural and alteration changes in basaltic lava flows using variations in rock magnetic properties (ODP Leg 183)

Tectonophysics (2003)

Heike Delius T. S. Brewer P.K. Harvey

Subaerial

Pillow lava

Rock magnetism

Natural remanent magnetization

10.1016/s0040-1951(03)00202-6

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Citations (13)

Magmatic cycles and formation of the upper oceanic crust at spreading centers: Geochemical study of a continuous extrusive section in the Oman Ophiolite

Florence Einaudi Marguerite Godard Philippe Pézard Jean‐Jacques Cochemé C. Coulon

[1] The data and analysis presented in this paper provide an assessment of lava morphologies and the geochemistry of lavas from the Oman ophiolite. In order to provide detailed constraints on the construction of the upper oceanic crust, a continuous volcanic transect (300 m-thick) was sampled at high-frequency in the Semail ophiolite along Wadi Shaffan. The Wadi Shaffan section is composed mainly of pillow lavas interbedded with massive flows and occasional hyaloclastites. The sampling performed along Wadi Shaffan implies temporal variations in the activity of the ridge. The section is characterized by chemical compositions consistent with those of V1-Geotimes volcanism. The Wadi Shaffan transect was built through two main petrological and geochemical sequences of volcanic activity. Trace element ratios (e.g. Zr/Nb and La/Yb) allow us to distinguish two main sequences with two different parental magmas. Differences in the degree of partial melting are required to explain these trace element ratio variations. Beyond these differences in parent melt composition, variations in trace element abundances (TiO2, Zr, REE) involve differentiation processes prior to emplacement. In the lower sequence, less differentiated lavas are in the upper part of the cycle. Magma mixing is proposed to explain this reversed geochemical evolution through time. In the upper sequence, geochemical analysis suggests a different magma chamber process. This sequence consists of multiple events of magma emplacement. Variations in trace element abundance suggest four magmatic cycles. Each magmatic cycle is characterized by primitive lavas evolving to more differentiated lavas with time. The upper sequence lavas appear to be in equilibrium with clinopyroxene and lower sills from the MTZ (Mantle-Crust Transition Zone) and with lower gabbros. We propose a model in which the upper sequence lavas were directly derived from the MTZ and lower gabbro sills and then transported to the surface without interaction with higher crustal levels. G Geochemistry Geophysics Geosystems

Pillow lava

Phenocryst

Trace element

Igneous differentiation

Magma chamber

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Citations (0)

The rapid determination of Rb, Sr and their ratios in geological materials by X-ray fluorescence spectrometry using a rhodium X-ray tube

Chemical Geology (1981)

P.K. Harvey Brian P. Atkin

X-Ray Fluorescence

X-ray tube

Gamma ray spectrometry

10.1016/0009-2541(81)90150-9

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Citations (20)