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Behaviour in Apatites, Scapolite, and Sodalite

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CORE Metadata, citation and similar papers at core.ac.uk Provided by University of Saskatchewan's Research Archive HALOGEN-ELEMENT (F, Cl, AND Br) BEHAVIOUR IN APATITES, SCAPOLITE, AND SODALITE: AN EXPERIMENTAL INVESTIGATION WITH FIELD APPLICATIONS A Thesis Submitted to the College of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Geological Sciences University of Saskatchewan Saskatoon By Ping Dong © Copyright Ping Dong, August, 2005. All Rights Reserved Permission to use In presenting this thesis in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or to make other use of material in this thesis in whole or part should be addressed to: Head of the Department of Geological Sciences University of Saskatchewan 114 Science Place Saskatoon, Saskatchewan Canada S7N 5E2 i Abstract Halogens (F, Cl, Br, and I) are common constituents in igneous, metamorphic, and sedimentary rocks, and are particularly important in the transport of many ore-forming metals. Detailed knowledge about the abundance of halogens in melts/fluids and minerals can help to interpret many geological processes. However, most hydrothermal fluids and melts cannot be directly sampled. Halogen-bearing minerals, such as apatites, scapolite and sodalite, can provide reliable information about the halogen concentrations in their parental fluids/melts provided that the partition coefficients between those minerals and fluids/melts are known. This is the first systematic experimental investigation of partitioning of Br between apatites and coexisting melts and the uptake of Br by scapolite and sodalite. Twenty-nine partitioning experiments between fluorapatite (FAP) /chlorapatite (ClAP) and coexisting melts were conducted in the system of CaO-P2O5-CaF 2-CaCl 2–NaBr at 1120 °C to 1400 °C and atmospheric pressure. The partition coefficients (D) with errors of 1 δ in parentheses are as follow: ii F D ClAP/melt 3.59(64) at 1120 °C to 4.13(22) at 1330 °C F D FAP/melt 1.05(4) at 1220 °C to 1.07 at 1400 °C Cl D ClAP/melt 1.07(1) at 1120 °C to 0.83 at 1330 °C Cl D FAP/melt 0.127(2) at 1250 °C to 0.115 at 1400 °C Br D ClAP/melt 0.32(9) at 1120 °C to 0.42(5) at 1330 °C Br D FAP/melt 0.020(3) at 1220 °C to 0.016 at 1400 °C Seven exchange experiments at one atmospheric pressure and 800 to 1000 °C yield the following distribution coefficients for Br-Cl exchanges between marialitic scapolite or sodalite and coexisting hydrous NaCl-NaBr marialite-melt sodalite-melt melts: K D = 0.92 ±0.10 and K D = 1.18 ±0.10. Therefore, the Cl/Br values in marialitic scapolite and sodalite closely reflect the halogen proportions of their coexisting melts or fluids. The second part of this thesis project analyzes the halogen (F, Cl, Br) contents in natural fluorapatite and scapolite by X-ray fluorescence microprobe (XRF) for Br and electron microprobe (EMPA) for other elements. All selected localities and environments are interesting, because the origins of the parental fluids/melts are controversial. The halogen compositions of 29 natural apatite grains from the Aoshan fluorapatite-magnetite deposit (China), the Oka carbonatite complex (Quebec), and Chinese mantle xenoliths and 36 scapolite samples from the Tieshan Fe-Cu skarn deposit (China), the Nickel Plate gold deposit (British Columbia), and the Grenville pegmatite/skarn/vein deposits (Ontario and Quebec) have been analyzed by electron microprobe (EMPA) and iii X-ray fluorescence microprobe (XRF). Twenty six whole-rock samples from the Aoshan deposit have also been analyzed by XRF for major and trace elements. Fluorapatite from the Aoshan fluorapatite-magnetite deposit is Cl- bearing with 0.38-0.98 wt% Cl, 1.83-3.45 wt% F, and 0-52 ppm Br. Fluorapatite from Chinese mantle xenoliths has similar halogen compositions to the Aoshan fluorapatite. Fluorapatite from the Oka carbonatite has trace amounts of chlorine (up to 0.052 wt%) and bromine (from 9 to 57 ppm). Applications for the experimental results suggest that the Aoshan Fe-Cu deposit has Cl/Br values comparable to those of mantle sources and that the anomalously low Cl/Br values in Oka fluorapatite require Br-enriched sources. The Cl/Br values (weight) of marialitic scapolite from the Tieshan Fe-Cu deposit cluster around 626 ±92, supporting an origin involving hydrothermal brines from associated evaporites. Scapolite-group minerals in the exoskarns of the Nickel Plate Au skarn deposit have Cl/Br from 560 to 570, higher than those (110 to 180) of their counterparts in the endoskarns and vuggy cavities. This variation is attributable to an increased involvement of magmatic water from distal to proximal zones. Similarly, scapolite-group minerals in the Grenvillian U-Th-Mo-REE pegmatite-skarn-vein deposits vary widely in Cl/Br from 80 to 380, indicative of mixed sources of hydrothermal fluids from magmatic sources and from associated sedimentary rocks. The experimentally determined partition coefficients of halogens between minerals (apatites, scapolite, and sodalite) and fluids/melts of this iv study have wide applications in the interpretation of source and evolution of hydrothermal fluids in mineralization processes and other geological systems. Applications of those partition coefficients to selected mineral deposits and mantle xenoliths confirm their significance. v Acknowledgements It is my pleasure to gratefully acknowledge the guidance, encouragement, and patience of my supervisor, Dr. Yuanming Pan. Sincere thanks to all the members of my advisory committee for constructive advice and patience (Drs. Kevin Ansdell, Jim Basinger, Robert Kerrich, Doug Milne, Steve Reid, and Mel Stauffer). Dr. D. Lentz (external examiner) is greatly appreciated for valuable suggestions and comments. Special thanks are extended to the technical staff, Tom Bonli, Blaine Novakovski, and Lloyd Litwin, at the Department of Geological Sciences, University of Saskatchewan. Grenvillian scapolite separates were kindly supplied by Dr. D. Lentz, Department of Geology, University of New Brunswick and apatites from Chinese mantle xenoliths were provided by Prof. Jianping, Zheng of Chinese University of Geosciences at Wuhan, Hubei, China. This thesis was partly supported by a Natural Sciences and Engineering Research Council (NSERC) grant to Dr. Pan, an University of Saskatchewan graduate scholarship and graduate teaching fellowship. I also would like to thank my friend, Peter Fehr, for proof reading of thesis draft, my wife, Jian Liu, and my son, Anqi, for their understanding and support. vi Table of Contents Permission to use ............................................................................................ i Abstract............................................................................................................ ii Acknowledgements........................................................................................ vi Table of Contents.......................................................................................... vii List of Figures................................................................................................. ix List of Tables .................................................................................................. xi 1. Introduction ................................................................................................. 1 2. Review on Halogens in Geological Environments ................................. 10 2.1 Chemical Properties of Halogen Elements ................................................... 10 2.2 Literature Data of Halogens in Geological Samples ................................... 10 2.3 Review of Previous Work ................................................................................ 15 2.3.1 General Research about Halogens in Geological Processes ............. 15 2.3.2 Terminology/Definition of the Partition Coefficient and Henry’s Law . 24 2.3.3 Previous Partitioning Research ............................................................... 27 3. Review on Crystal Chemistry, Stabilities and Experimental Studies of Apatite, Scapolite, and Sodalite................................................................... 33 3.1 Crystal Structure of Apatite-Group Minerals ................................................ 33 3.2 Experimental Studies of Apatite-Group Minerals ........................................ 35 3.3 Crystal Structure of Scapolite-Group Minerals ............................................ 37 3.4 Experimental Studies of Scapolite-Group Minerals .................................... 39 3.5 Sodalite .............................................................................................................. 41 4. Analytical Methods...................................................................................
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