Universität zu Köln

Wellnitz, A. Katrin, Scott, James M., Martin, Candace E., Palin, J. Michael, Stirling, Claudine H., Reid, Malcolm R., Wombacher, F. and Craw, Dave (2019). Carbonation reactions and coupled element and isotope redistribution during shallow crustal gold mineralisation, New Zealand. Miner. Depos., 54 (5). S. 743 - 761. NEW YORK: SPRINGER. ISSN 1432-1866

Full text not available from this repository.

Abstract

Hydrothermal alteration zones rich in carbonate are excellent vectors for orogenic gold-bearing veins, but the extent of element mobility is difficult to establish. Whole rock and in situ mineral analysis was performed to better understand the element and isotope (Sr, Nd, C) redistribution around Miocene quartz-carbonate-sulphide-gold-bearing veins in meta-turbidite (greyschist) and meta-basite (greenschist) in the Otago Schist in New Zealand. The new data provide insight into the fluid-rock interaction within a lithologically, chemically and isotopically heterogeneous upper few kilometres (<5km) of crust. The relative resistance of metamorphic minerals to complete breakdown in mineralising fluids with high CO2 activity was epidote < titanite < actinolite < chlorite and muscovite, with their breakdown promoting simultaneous precipitation of carbonate, white mica, rutile, quartz, pyrite, arsenopyrite, barite, scheelite and gold. At the hand specimen scale, mass balance calculations suggest that major elements and large-ion lithophile elements (K, Rb, Cs, Ba +/- Sr) were mobile, whereas high-field strength elements (HFSE; Ti, Nb, Zr, Hf) were immobile. In detail, however, Zr and Hf were mobile at the microscopic scale during the replacement of metamorphic titanite. Similarly, rare earth elements (REE; La to Lu) appeared immobile at the hand specimen scale but were mobile at the microscopic scale because epidote, the main metamorphic REE reservoir, was replaced by REE-free white mica. The limited hand specimen-scale REE mobility was due to the formation of hydrothermal calcite, ankerite and magnesite, which almost immediately bound these elements into their crystal structures. Conventionally obtained C-13 and bulk Sr-87/Sr-86 isotopes, augmented with in situ laser ablation analysis of Sr-87/Sr-86 of hydrothermal carbonate and metamorphic epidote, show that the mineralising fluids reacted with greyschists and greenschists, even when these lithologies were not close by. The elemental and isotopic compositions of the hydrothermal minerals in this shallow gold-bearing system were evidently affected by distal and proximal metasomatic reactions.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Wellnitz, A. Katrin UNSPECIFIED UNSPECIFIED UNSPECIFIED Scott, James M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Martin, Candace E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Palin, J. Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED Stirling, Claudine H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Reid, Malcolm R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wombacher, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Craw, Dave UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-147545
DOI:	10.1007/s00126-018-0838-9
Journal or Publication Title:	Miner. Depos.
Volume:	54
Number:	5
Page Range:	S. 743 - 761
Date:	2019
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1432-1866
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language OTAGO SCHIST; HYDROTHERMAL ALTERATION; STRUCTURAL CONTROLS; CENTRAL VICTORIA; MASS-TRANSFER; DEPOSITS; BELT; GEOCHEMISTRY; FLUIDS; METAMORPHISM Multiple languages Geochemistry & Geophysics; Mineralogy Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14754