Sr-Nd-Pb isotopic systematics of Australasian tektites: Implications for the nature and composition of target materials and possible volatile loss of Pb

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F20%3A00000021" target="_blank" >RIV/00025798:_____/20:00000021 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1016/j.gca.2020.02.025" target="_blank" >https://doi.org/10.1016/j.gca.2020.02.025</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.gca.2020.02.025" target="_blank" >10.1016/j.gca.2020.02.025</a>

Result language

angličtina

Original language name

Sr-Nd-Pb isotopic systematics of Australasian tektites: Implications for the nature and composition of target materials and possible volatile loss of Pb

Original language description

The Australasian tektite (AAT) strewn field is the largest strewn field on the Earth with about ~10–30percent coverage, both land and ocean, but a clearly identified source impact crater is absent despite a young age of AAT at ca. 790 ka. A genetic link between the Australasian tektites and their unequivocal parental materials is therefore largely impossible to establish. Nevertheless, the nature of the parental materials and the extent of volatilization can be constrained using the splash form tektites, carrying the chemical signatures of high-temperature processes, and the layered (so-called Muong Nong-type) tektites, which are less chemically homogenized and exceptionally abundant in the AAT field. The new high-precision Sr, Nd and Pb isotopic measurements have been obtained for a chemically and petrographically well-characterized suite of AAT, which included Muong Nong-type (MN-AAT) with precisely known field locations in Laos and splash forms (SF-AAT) from different parts of the strewn field. In addition, optically dark and light zones of the MN-AAT have also been analyzed. Homogeneous eNd values from &#8722;11.8 to &#8722;11.2, combined with a narrow range of two-stage Nd model ages from 1.67 to 1.72 Ga for the entire AAT suite, point to a well-mixed source of the crustal segment in terms of REE from which the sedimentary material for tektites was ultimately derived. The Sr isotopic data largely overlap for SF-AAT and MN-AAT (87Sr/86Sr = 0.71636–0.72021) and indicate Paleozoic to Mesozoic sedimentary parentage. However, late Neogene to early Quaternary re-deposition and formation of a thick silt-sized sedimentary section with vertical stratification is required to comply with 10Be data. Lead isotopic systematics document at least three different components which can perhaps be represented by different mineral phases, such as feldspar, zircon, organic matter adsorbed on young sediments etc., sorted during riverine transport and final deposition. In addition, the SF-AAT lost considerably more Pb than the MN-AAT, and generally have isotopically heavier Pb isotopic ratios. This is theoretically consistent with preferential volatilization of lighter Pb isotopes during evaporation, but experimental work would be necessary to unambiguously distinguish kinetic fractionation from source mixing.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10505 - Geology

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2020

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Geochimica et Cosmochimica Acta

ISSN

0016-7037

e-ISSN

—

Volume of the periodical

276

Issue of the periodical within the volume

May 1

Country of publishing house

GB - UNITED KINGDOM

Number of pages

16

Pages from-to

135-150

UT code for WoS article

000525416100009

EID of the result in the Scopus database

2-s2.0-85081350967