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Type: Journal article
Title: Mantle heating at ca. 2 Ga by continental insulation: Evidence from granites and eclogites
Author: Tamblyn, R.
Hasterok, D.
Hand, M.
Gard, M.
Citation: Geology (Boulder), 2022; 50(1):91-95
Publisher: Geological Society of America
Issue Date: 2022
ISSN: 0091-7613
Statement of
R. Tamblyn, D. Hasterok, M. Hand and M. Gard
Abstract: Igneous and metamorphic rocks contain the mineralogical and geochemical record of thermally driven processes on Earth. The generally accepted thermal budget of the mantle indicates a steady cooling trend since the Archean. The geological record, however, indicates this simple cooling model may not hold true. Subduction-related eclogites substantially emerge in the rock record from 2.1 Ga to 1.8 Ga, indicating that average mantle thermal conditions cooled below a critical threshold for widespread eclogite preservation. Following this period, eclogite disappeared again until ca. 1.1 Ga. Coincident with the transient emergence of eclogite, global granite chemistry recorded a decrease in Sr and Eu and increases in yttrium and heavy rare earth element (HREE) concentrations. These changes are most simply explained by warming of the thermal regime associated with granite genesis. We suggest that warming was caused by increased continental insulation of the mantle at this time. Ultimately, secular cooling of the mantle overcame insulation, allowing the second emergence and preservation of eclogite from ca. 1.1 Ga until present.
Rights: © 2021 Geological Society of America. For permission to copy, contact
DOI: 10.1130/G49288.1
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Appears in Collections:Physics publications

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