Journal ArticleDOI
Evidence of growth and sector zoning in hydrothermal quartz from Alpine veins
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In this paper, the incorporation of trace elements into hydrothermal quartz from Alpine veins is influenced by growth mechanisms and surface-structures of the growing quartz crystals, the influence of which may change as a function of temperature, pH, as well as the chemical composition of the fluid.Abstract:
Several quartz crystals from three different Alpine vein localities and of known petrologic setting and evolution have been examined for possible elemental sector zoning in order to help to constrain the mechanisms of such trace element incorporation. Using different in situ techniques (EMPA, LA-ICPMS, SIMS, FTIR-spectroscopy), it was established that Al and Li concentrations can exceed several hundreds of ppma for distinct growth zones within crystals formed at temperatures of about 300 °C or less and that also display patterns of cyclic growth when examined with cathodoluminescence. In contrast, crystals formed at temperatures closer to 400 °C and without visible cyclic growth have low concentrations of Al and Li as well as other trace elements. Al and Li contents are correlated along profiles measured within the crystals and in general their proportion does not change along the profiles. No relationships were found between Al, Na, and K, and germanium has a qualitative relationship with Al. FTIR spectra also show OH − absorption bands within the quartz, with higher amplitudes in zones rich in Al and Li. Sector zoning is present. It is most pronounced between prismatic and rhombohedral faces of the same growth zone, but also between the rhombohedral faces of r and z , which contain different amounts of trace elements. The sector zoning is also expressed by changes in the Li/Al ratio, with higher ratios in z compared to r faces. It is concluded that the incorporation of trace elements into hydrothermal quartz from Alpine veins is influenced by growth mechanisms and surface-structures of the growing quartz crystals, the influence of which may change as a function of temperature, pH, as well as the chemical composition of the fluid.read more
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Journal ArticleDOI
Trace elements and cathodoluminescence of quartz in stockwork veins of Mongolian porphyry-style deposits
Axel H. E. Müller,Richard Herrington,Robin Armstrong,Reimar Seltmann,Douglas J. Kirwin,Nina G. Stenina,Andreas Kronz +6 more
Abstract: The combination of scanning electron microscope–cathodoluminescence (CL), fluid inclusion analysis and high-resolution electron probe microanalysis of Al, Ti, K and Fe in vein quartz has yielded results permitting a greater understanding of the complex mineralisation of the Central Oyu Tolgoi and Zesen Uul porphyry-style deposits, southern Mongolia. These data demonstrate the relationship between quartz precipitation, dissolution and ore deposition as the mineralising fluid chemistry changed through time. Four major quartz generations are identified in the A-type veins from the stockworks of both the Central Oyu Tolgoi (OTi to OTiv) and Zesen Uul deposits (ZUi to ZUiv). Despite differences in the associated alteration and mineralisation style, the observed CL textures and trace element signatures of the quartz generations are comparable between deposits. The OTi and ZUi stage formed both the primary network of A-type veins and pervasive silicification of the host rock. Using the Ti-in-quartz geothermometer, crystallisation temperatures for OTi and ZUi of between 598°C and 880°C are indicated. The main stage of sulphide mineralisation was accompanied by the dissolution of pre-existing quartz (OTi and ZUi) and precipitation of a weakly luminescent generation of quartz (OTii and ZUii) with a low Ti content, reflected in a calculated temperature drop from approximately 700°C to 340°C in Central Oyu Tolgoi and 445°C in Zesen Uul. OTii and ZUii stage quartzes show high and variable Al concentrations. The next stage of quartz in both deposits (OTiii and ZUiii) forms a fine network of veins in cracks formed in pre-existing quartz. OTiii and ZUiii quartz contain measurable fluid inclusions of moderate salinity (3–17.1 wt.% NaCl eq.), entrapped in the temperature range 256°C to 385°C. OTiii and ZUiii are not related to any sulphide mineralisation. The final OTiv and ZUiv stages are characterised by quartz–calcite micro-breccias that penetrate the A-type veins. Based on the calculated entrapment temperatures, the OTiv/ZUiv stage crystallised between 212°C and 335°C, and the quartz is characterised by elevated but variable Al and Fe contents. The CL and trace element signatures of the OTi to OTiii and ZUi to ZUiii stages of the two Mongolian porphyries show similar features to those observed in porphyry-style deposits from other regions. This suggests that a common sequence of quartz crystallisation occurs during the formation of early veins in many porphyry copper systems.
Journal ArticleDOI
Hydrogen speciation and trace element contents of igneous, hydrothermal and metamorphic quartz from Norway
A. Müller,M. Koch-Müller +1 more
TL;DR: In this article, a refined hypothetical charge neutrality equation is suggested, where the atomic ratio of (Al3+ +Fe3++ +B3+) to (P5+ +H+ +Li+ +Na+ +K+) should correspond to 1 for natural quartz crystals.
Journal ArticleDOI
Physical and Chemical Evolution of the Dabaoshan Porphyry Mo Deposit, South China: Insights from Fluid Inclusions, Cathodoluminescence, and Trace Elements in Quartz
TL;DR: The Dabaoshan porphyry Mo deposit as discussed by the authors is characterized by the superposition of multiple generations of crosscutting quartz-bearing veins including: barren quartz veins (V1), quartz-molybdenite veins with K-feldspar alteration halos that host the bulk of the Mo mineralization, and late base metal mineralization with argillic alteration (V4), as well as limestone-hosted strata-bound Cu-Pb-Zn mineralization (VS).
Book ChapterDOI
Petrological and Chemical Characterisation of High-Purity Quartz Deposits with Examples from Norway
TL;DR: In this article, a refined definition of high purity quartz (HPQ) and a discussion of the impurities controlling the chemical quality of HPQ products and descriptions of selected HPQ deposits in Norway, both economic and potentially economic examples are discussed.
Journal ArticleDOI
Growth related zonations in authigenic and hydrothermal quartz characterized by SIMS-, EPMA-, SEM-CL- and SEM-CC-imaging
TL;DR: Authigenic quartz overgrowths and hydrothermal quartz crystals from locations in Oman and Switzerland have been investigated with SIMS, EPMA, SEM-CL and SEM-CC as mentioned in this paper.
References
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Journal ArticleDOI
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Journal ArticleDOI
TitaniQ: a titanium-in-quartz geothermometer
David A. Wark,E. Bruce Watson +1 more
TL;DR: In this paper, the temperature dependence of substitution for silicon in the form of a new geothermometer was described, and the Ti contents of quartz (in ppm by weight) from 13 experiments increase exponentially with reciprocal T as described by.
Journal ArticleDOI
Relationship between surface structure, growth mechanism, and trace element incorporation in calcite
TL;DR: In this paper, a model detailing the geometry and coordination of elementary kink sites is presented to explain both the differential incorporation and the rate anisotropy between nonequivalent growth steps on individual {1014} faces.
BookDOI
Cathodoluminescence in Geosciences
TL;DR: In this article, the authors describe the use of the CLC-Method for the interpretation of U-Pb Zircon ages, with an example of an application to a study of Zircons from the Saxonian Granulite Complex, Germany.
Journal ArticleDOI
Origin, spectral characteristics and practical applications of the cathodoluminescence (CL) of quartz – a review
TL;DR: In this article, the authors investigated the role of intrinsic and extrinsic defects such as the alkali (or hydrogen)-compensated [AlO4/M+] center and the short-lived blue-green CL centered around 500 µm in the red spectral region.