Publication detail

Water contents and hydrogen isotope compositions of amphibole in aillikites from the Tarim large igneous province, NW China: Insight into Earth's deep water cycle

WANG, C. ZHANG, Z. GIULIANI, A. BO, H. KRMÍČEK, L. LI, X.

Original Title

Water contents and hydrogen isotope compositions of amphibole in aillikites from the Tarim large igneous province, NW China: Insight into Earth's deep water cycle

Type

journal article in Web of Science

Language

English

Original Abstract

Water is known to play a crucial role in the generation of many large igneous provinces (LIP) worldwide, but the amount and origin of the water in their sources is still under debate. To address this question, this paper presents in situ major-, trace-element, and Sr isotope data coupled with bulk-mineral O-H-He isotope analyses of amphibole in a suite of aillikites from the Tarim LIP (NW China). The cores of zoned macrocrysts and microcrysts display partially overlapping compositions ranging between edenite and pargasite (75-83 versus 75-80 Mg#), which suggest a common origin from an evolving magma. The rims (Mg# = 75-80) of both macrocrysts and microcrysts are very similar to their cores for many elements, except for higher Sr and Ba contents. All the amphibole zones show similar primitive mantle-normalized trace element patterns, suggesting that they crystallized at different stages during magmatic evolution. This interpretation is confirmed by the homogenous Sr isotope compositions (Sr-87/Sr-86((i)) = 0.70298-0.70394) of these amphiboles, which overlap with those of magmatic apatites and perovskites in these aillikites. The hydrogen isotope compositions (delta D = -120 parts per thousand to -140 parts per thousand) of the amphiboles are significantly lower than average mantle values. Given the low water contents (<0.66 wt%) of these minerals, the low H isotope signatures of the amphiboles might be caused by variable H2O loss during magma ascent. However, open-system Rayleigh fractionation modeling suggests that the hydrogen isotope compositions of these amphibole phenocrysts cannot be fully reproduced by crystallization following magmatic degassing. These low delta D values require incorporation of recycled altered oceanic crust containing hydrous components in the plume source of these aillikites, which is consistent with the previously published moderately radiogenic He isotope ratios of olivine separates and bulk-rock Os and Pb isotope data for these same samples. We conclude that water in these magmas was derived from a plume source containing recycled water-bearing oceanic crust.

Keywords

aillikite; amphibole; O-H-He isotopes; Tarim LIP

Authors

WANG, C.; ZHANG, Z.; GIULIANI, A.; BO, H.; KRMÍČEK, L.; LI, X.

Released

7. 7. 2024

Publisher

GEOLOGICAL SOC AMER, INC

Location

BOULDER

ISBN

0016-7606

Periodical

GEOLOGICAL SOCIETY OF AMERICA BULLETIN

Year of study

136

Number

5-6

State

United States of America

Pages from

2097

Pages to

2110

Pages count

14

URL

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/136/5-6/2097/628227/Water-contents-and-hydrogen-isotope-compositions?redirectedFrom=fulltext

BibTex

@article{BUT194046,
  author="Changhong {Wang} and Zhaochong {Zhang} and Andrea {Giuliani} and Hongze {Bo} and Lukáš {Krmíček} and Xiaoguang {Li}",
  title="Water contents and hydrogen isotope compositions of amphibole in aillikites from the Tarim large igneous province, NW China: Insight into Earth's deep water cycle",
  journal="GEOLOGICAL SOCIETY OF AMERICA BULLETIN",
  year="2024",
  volume="136",
  number="5-6",
  pages="2097--2110",
  doi="10.1130/B36906.1",
  issn="0016-7606",
  url="https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/136/5-6/2097/628227/Water-contents-and-hydrogen-isotope-compositions?redirectedFrom=fulltext"
}