University of Tasmania
Browse

File(s) under permanent embargo

Magma chamber-scale liquid immiscibility in the Siberian Traps represented by melt pools in native iron

journal contribution
posted on 2023-05-17, 19:44 authored by Vadim Kamenetsky, Charlier, B, Zhitova, L, Sharygin, V, Paul DavidsonPaul Davidson, Sandrin FeigSandrin Feig
Magma unmixing (i.e., separation of a homogeneous silicate melt into two or more liquids) is responsible for sudden changes in the evolution of common melts, element fractionation, and potential formation of orthomagmatic ore deposits. Although immiscible phases are a common phenomenon in the mesostasis of many tholeiitic basalts, evidence of unmixing in intrusive rocks is more difficult to record because of the transient nature of immiscibility during decompression, cooling, and crystallization. In this paper, we document a clear case of liquid immiscibility in an intrusive body of tholeiitic gabbro in the Siberian large igneous province, using textures and compositions of millimeter-sized silicate melt pools in native iron. The native iron crystallized from a metallic iron liquid, which originated as disseminated globules during reduction of the basaltic magma upon interaction with coal-bearing sedimentary rocks in the Siberian craton. The silicate melts entrapped and armored by the native iron are composed of two types of globules that represent the aluminosilicate (60-77 wt% SiO2) and silica-poor, Fe-Ti-Ca-P-rich (in wt%: SiO2, 15-46; FeO, 15-22; TiO2, 2-7; CaO, 11-27; P2O5, 5-30) conjugate liquids. Different proportions and the correlated compositions of these globules in individual melt pools suggest a continuously evolving environment of magmatic immiscibility during magma cooling. These natural immiscible melts correspond extremely well to the conjugate liquids experimentally produced in common basaltic compositions at <1025 °C. Our results show that immiscibility can occur at large scale in magma chambers and can be instrumental in generating felsic magmas and Fe-Ti-Ca-P-rich melts in the continental igneous provinces.

Funding

Australian Research Council

History

Publication title

Geology

Volume

41

Issue

10

Pagination

1091-1094

ISSN

0091-7613

Department/School

School of Natural Sciences

Publisher

Geological Society America

Place of publication

Boulder, USA

Rights statement

Copyright 2013 Geological Society of America

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC