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Oscillatory zoning and trace element incorporation in hydrothermal minerals: insights from calcite growth experiments

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posted on 2023-05-19, 22:41 authored by Shaun BarkerShaun Barker, Cox, SF
Oscillatory zoning and fine‐scale variations in trace element chemistry are commonly observed in hydrothermal minerals. It has been suggested that fine‐scale chemical variations are caused by extrinsic changes in the parent hydrothermal system, such as varying fluid composition, pressure or temperature, as well as changes in mineral growth rate. In this study, LA–ICP–MS (laser ablation, inductively coupled plasma mass spectrometer) analyses were carried out on calcite crystals grown in Ca–NH3–Cl solutions doped with rare earth elements (REE). The variety of crystal morphologies observed (euhedral to acicular), likely relate to variations in trace element abundance and calcite supersaturation state. Crystals display oscillatory and sector zoning, with significant variations in REE concentrations among zones. Cyclic variations in REE concentrations (exceeding 10‐fold) occur over distances of <1 mm along the growth direction of acicular calcite crystals. In general, trace element concentrations decrease during progressive crystal growth, implying that the concentration of trace and REEs within crystals reflects the overall composition of the growth solution. However, bulk changes in crystal composition are modulated by fine‐scale (<1 mm) variations, which are inferred to be caused by growth‐rate‐controlled incorporation of trace elements. These results have important implications for using hydrothermal minerals to infer fluctuations in fluid compositions in ancient, exhumed hydrothermal systems.

History

Publication title

Geofluids

Volume

11

Pagination

48-56

ISSN

1468-8115

Department/School

School of Natural Sciences

Publisher

Blackwell Publ Ltd

Place of publication

108 Cowley Rd, Oxford, England, Oxon, Ox4 1Jf

Rights statement

Copyright 2010 Blackwell Publishing Ltd. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

Repository Status

  • Open

Socio-economic Objectives

Expanding knowledge in the earth sciences

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