English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. We test whether X-ray micro-computed tomography (microCT)imaging can be used as a tool for screening magnetite grains to improve theaccuracy and precision of cosmogenic 3He exposure dating. We extracteddetrital magnetite from a soil developed on a fanglomerate at Whitewater,California, which was offset by the Banning strand of the San Andreas Fault.This study shows that microCT screening can distinguish betweeninclusion-free magnetite and magnetite with fluid or common solidinclusions. Such inclusions can produce bulk 3He concentrations thatare significantly in excess of the expected spallation production. Wepresent Li concentrations, major and trace element analyses, and estimatedmagnetite (U–Th) / He cooling ages of samples in order to model thecontribution from fissiogenic, nucleogenic, and cosmogenic thermal neutronproduction of 3He. We show that mineral inclusions in magnetite canproduce 3He concentrations of up to 4 times that of the spallationcomponent, leading to erroneous exposure ages. Therefore, grains withinclusions must be avoided in order to facilitate accurate and precisemagnetite 3He exposure dating. Around 30 % of all grains were foundto be without inclusions, as detectable by microCT, with the largestproportion of suitable grains in the grain size range of 400–800 µm.While grains with inclusions have 3He concentrations far in excess ofthe values expected from existing 10Be and 26Al data in quartz atthe Whitewater site, magnetite grains without inclusions have concentrationsclose to the predicted depth profile. We measured 3He concentrations inaliquots without inclusions and corrected them for Li-produced components.By comparing these data to the known exposure age of 53.5 ± 2.2 ka, wecalibrate a production rate for magnetite 3He at sea level and high latitude (SLHL) of 116 ± 13 at g−1 a−1. We suggest that this microCT screening approach can beused to improve the quality of cosmogenic 3He measurements of magnetiteand other opaque mineral phases for exposure age and detrital studies.

geochronology

Exposure dating of detrital magnetite using &amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;He enabled by microCT and calibration of the cosmogenic &amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;He production rate in magnetite