Title
Toward the feldspar alternative for cosmogenic <sup>10</sup>Be applications
Date Issued
01 August 2017
Access level
metadata only access
Resource Type
journal article
Publisher(s)
Elsevier B.V.
Abstract
The possibility of quantifying surface processes in mafic or volcanic environment using the potentialities offered by the in situ-produced cosmogenic nuclides, and more specifically by the in situ-produced 10Be, is often hampered by the rarity of quartz minerals in the available lithologies. As an alternative to overcome this difficulty, we explore in this work the possibility of relying on feldspar minerals rather that on quartz to perform in situ-produced 10Be measurements in such environments. Our strategy was to cross-calibrate the total production rate of 10Be in feldspar (P10fsp) against the total production rate of 3He in pyroxene (P3px) by measuring 3He and 10Be in cogenetic pyroxene (3Hepx) and feldspar (10Befsp). The samples were collected from eight ignimbritic boulders, exposed from ca 120 to 600 ka at elevations ranging from 800 to 2500 m, along the preserved rock-avalanche deposits of the giant Caquilluco landslide (18°S, 70°W), Southern Peru. Along with data recently published by Blard et al. (2013a) at a close latitude (22°S) but higher elevation (ca. 4000 m), the samples yield a remarkably tight cluster of 3Hepx - 10Befsp total production ratios whose weighted-mean is 35.6 ± 0.5 (1σ). The obtained weighted-mean 3Hepx - 10Befsp total production ratio combined with the local 3Hepy total production rate in the high tropical Andes published by Martin et al. (2017) allows to establish a total SLHL 10Be in situ-production rate in feldspar mineral (P10fsp) of 3.57 ± 0.21 at.g−1.yr−1 (scaled for the LSD scaling scheme, the ERA40 atm model and the VDM of Lifton, 2016). Despite the large elevation range covered by the whole dataset (800–4300 m), no significant variation of the 3Hepx - 10Befsp total production ratios in pyroxene and feldspar was evidenced. As an attempt to investigate the effect of the chemical composition of feldspar on the total 10Be production rate, major and trace element concentrations of the studied feldspar samples were analyzed. Unfortunately, giving the low compositional variability of our dataset, this issue is still pending.
Start page
83
End page
96
Volume
41
Language
English
OCDE Knowledge area
Vulcanología
Scopus EID
2-s2.0-85021673605
Source
Quaternary Geochronology
ISSN of the container
18711014
Sponsor(s)
This publication is part of the convenio IRD-INGEMMET. The work has been supported by INSU SYSTER, the ANR Jeunes Chercheurs GALAC project (ANR-11-JS56-011-01), the CNES and a grant from Labex OSUG@2020 (Investissements d'avenir – ANR10 LABX56). We warmly thank François Senebier, Sylvain Campillo, Valerie Magan, Nathaniel Findling and Catherine Chauvel for ICP-MS measurements, geochemical analysis and fruitful discussions. The measurements were performed at the ASTER AMS national facility (CEREGE, Aix en Provence) which is supported by the INSU,CNRS, the ANR through the ‟Projets thématiques d'excellence” program for the ‟Equipements d'excellence” ASTER-CEREGE action and IRD. We thank Shasta Marrero and Samuel Niedermann for their very constructive reviews.
Sources of information: Directorio de Producción Científica Scopus