Papers by Jan Marten Huizenga
Economic Geology, 2020
The Mt. Carlton Au-Ag-Cu deposit, northern Bowen basin, northeastern Australia, is an uncommon ex... more The Mt. Carlton Au-Ag-Cu deposit, northern Bowen basin, northeastern Australia, is an uncommon example of a sublacustrine hydrothermal system containing economic high-sulfidation epithermal mineralization. The deposit formed in the early Permian and comprises vein-and hydrothermal breccia-hosted Au-Cu mineraliza-tion within a massive rhyodacite porphyry (V2 open pit) and stratabound Ag-barite mineralization within volcano -lacustrine sedimentary rocks (A39 open pit). These orebodies are all associated with extensive advanced argillic alteration of the volcanic host rocks. Stable isotope data for disseminated alunite (δ 34 S = 6.3-29.2‰; δ 18 OSO 4 =-0.1 to 9.8‰; δ 18 OOH =-15.3 to-3.4‰; δD =-102 to-79‰) and pyrite (δ 34 S =-8.8 to-2.7‰), and void-filling anhydrite (δ 34 S = 17.2-19.2‰; δ 18 OSO 4 = 1.8-5.7‰), suggest that early advanced argillic alteration formed within a magmatic-hydrothermal system. The ascending magmatic vapor (δ 34 SSS ≈-1.3‰) was absorbed by meteoric water (~50-60% meteoric component), producing an acidic (pH ≈ 1) condensate that formed a silicic → quartz-alunite → quartz-dickite-kaolinite zoned alteration halo with increasing distance from feeder structures. The oxygen and hydrogen isotope compositions of alunite-forming fluids at Mt. Carlton are lighter than those documented at similar deposits elsewhere, probably due to the high paleolatitude (~S60°) of northeastern Australia in the early Permian. Veins of coarse-grained, banded plumose alunite (δ 34 S = 0.4-7.0‰; δ 18 OSO 4 = 2.3-6.0‰; δ 18 OOH =-10.3 to-2.9‰; δD =-106 to-93‰) formed within feeder structures during the final stages of advanced argillic alteration. Epithermal mineralization was deposited subsequently, initially as fracture-and fissure-filling, Au-Cu-rich assemblages within feeder structures at depth. As the miner-alizing fluids discharged into lakes, they produced syngenetic Ag-barite ore. Isotope data for ore-related sulfides and sulfosalts (δ 34 S =-15.0 to-3.0‰) and barite (δ 34 S = 22.3-23.8‰; δ 18 OSO 4 =-0.2 to 1.3‰), and micro-thermometric data for primary fluid inclusions in barite (Th = 116°-233°C; 0.0-1.7 wt % NaCl), are consistent with metal deposition at temperatures of ~200 ± 40°C (for Au-Cu mineralization in V2 pit) and ~150 ± 30°C (Ag mineralization in A39 pit) from a low-salinity, sulfur-and metal-rich magmatic-hydrothermal liquid that mixed with vapor-heated meteoric water. The mineralizing fluids initially had a high-sulfidation state, producing enargite-dominated ore with associated silicification of the early-altered wall rock. With time, the fluids evolved to an intermediate-sulfidation state, depositing sphalerite-and tennantite-dominated ore mineral assemblages. Void-filling massive dickite (δ 18 O =-1.1 to 2.1‰; δD =-121 to-103‰) with pyrite was deposited from an increasingly diluted magmatic-hydrothermal liquid (≥70% meteoric component) exsolved from a progressively degassed magma. Gypsum (δ 34 S = 11.4-19.2‰; δ 18 OSO 4 = 0.5-3.4‰) occurs in veins within postmineraliza-tion faults and fracture networks, likely derived from early anhydrite that was dissolved by circulating meteoric water during extensional deformation. This process may explain the apparent scarcity of hypogene anhydrite in lithocaps elsewhere. While the Mt. Carlton system is similar to those that form subaerial high-sulfidation epithermal deposits, it also shares several key characteristics with magmatic-hydrothermal systems that form base and precious metal mineralization in shallow-submarine volcanic arc and back-arc settings. The lacus-trine paleosurface features documented at Mt. Carlton may be useful as exploration indicators for concealed epithermal mineralization in similar extensional terranes elsewhere.
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Ore Geology Reviews
Located in the eastern section of the Central Asian Orogenic Belt, the Jiawula Ag-Pb-Zn deposit i... more Located in the eastern section of the Central Asian Orogenic Belt, the Jiawula Ag-Pb-Zn deposit is classified as a volcanic to subvolcanic related vein-type ore deposit. New U-Pb zircon geochronology, whole-rock geochemistry, mineral chemistry, and Sr-Nd isotope data are presented for the intrusions in the Jiawula deposit in order to evaluate the timing, petrogenetic type of the granitoid rocks, origin and evolution of magmatism, geodynamics, and to establish its relationship with lead-zinc mineraliza-tion. Zircon SHRIMP U-Pb analyses yield weighted mean ages of 150.1 ± 1.8 Ma for quartz porphyry, 148.8 ± 2.2 Ma for syenite porphyry, and 145.3 ± 1.9 Ma for monzonite porphyry, indicating a Late Jurassic (Yanshanian) magmatic event. An earlier magmatic event (Indosinian) occurred during the Late Permian to Early Triassic from ca. 254 Ma to ca. 247 Ma and is represented by granodiorite (254 ± 2 Ma), dacite porphyry (252.9 ± 4.8 Ma), and diorite porphyry (278 ± 4.1 Ma). Both the Indosinian and Yanshanian igneous rocks are classified as I-type granitoids. The late Jurassic intrusions are highly fractionated and characterized by negative anomalies of Eu, Sr, P, and Ti. The hypabyssal intrusions have initial 87 Sr/ 86 Sr values between 0.70458 and 0.70522, and e Nd (t) values of À3.4 to À0.2, indicating relatively older crust in Jiawula among more juvenile crust in this area. Magma generation in Jiawula is linked to juvenile lower crustal and slightly enriched mantle sources. The $250 Ma magmatic episode in Jiawula might be related to the subduction of the Mongol-Okhotsk oceanic plate towards the south beneath the Erguna massif. The $150 Ma magmatic event occurred after the closure of the Mongol-Okhotsk Ocean followed by the change in subduction direction of the Paleo-Pacific plate. Varying temperature, stronger fractionation and higher oxygen fugacity related to the magmatic-hydrothermal transition caused Pb-Zn mineralization.
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Water SA , Apr 2013
A national dataset of inorganic chemical data of surface waters (rivers, lakes, and dams) in Sout... more A national dataset of inorganic chemical data of surface waters (rivers, lakes, and dams) in South Africa is presented and made freely available. The dataset comprises more than 500 000 complete water analyses from 1972 up to 2011, collected from more than 2 000 sample monitoring stations in South Africa. The dataset includes the major ion chemical composition and numerous calculated variables that can, amongst others, be used to determine accuracy of the analysis. The methods described here have potential for improving quality control measures in water chemistry laboratories by detecting anomalous samples. The processed data are available in Excel spreadsheets and can be downloaded from the website of the Centre for Water Science and Management based at the North-West University (www.waterscience.co.za/waterchemistry/data.html).
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Strontium has 4 naturally-occurring isotopes (84 Sr, 86 Sr, 87 Sr, 88 Sr) all of which are stable... more Strontium has 4 naturally-occurring isotopes (84 Sr, 86 Sr, 87 Sr, 88 Sr) all of which are stable (Faure, 1986). e correlation between the 87 Sr/ 86 Sr isotope ratio of lake water and sh n spine tissue was investigated in 23 lakes within 4 major South African catchments. Data showed that sh within a specic lake all have the same Sr isotope ratio in their n spine tissue regardless of species, age, sex and condition. e origin of the dissolved Sr fraction in lake water can be either from the natural weathering of upstream geological units or from an upstream anthropogenic source. e Sr isotopic ratios of the water samples were, however, constant over a multi-year period suggesting that the main source may be the more consistent geological environment. e Sr isotope ratio of river and lake water generally increases along the course of the rivers within the tertiary catchments of the areas investigated. In large rivers like the Vaal, where pollution also plays a role, the pattern is much more complicated. In the Olifants River catchment, Lake Middelburg, Lake Witbank and Lake Doornpoort have a similar Sr isotope ratio, which is distinct from Lake Bronkhorstspruit. Lake Loskop which is downstream from these lakes has a Sr isotope ratio between these two extremes, indicating mixing of water from upstream sources. Similarly Lake Arabie (Flag Boshielo), which is even further downstream, shows a Sr isotope composition between the composition of Lake Loskop and the lakes in the Elands River.
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Chemical elements in lake water are incorporated into fish tissues through bioconcentration and b... more Chemical elements in lake water are incorporated into fish tissues through bioconcentration and biomagnification. Lake water and fish tissue samples from 23 lakes, located within 4 major South African catchments, were analysed to investigate the link between element concentrations in lake water and otolith, fin spine, muscle, liver and gill tissues. The comparison is complicated by the seasonal variation in water chemistry as well as the large natural variation between individual fish within a lake. Comparisons between fish from different lakes can also only be done within the same species, which may not occur within all the lakes within the project area. This may be further complicated by erratic anthropogenic contamination. It is therefore more successful to use inter-element ratios for comparison than absolute element concentrations. Using the Sr/Ca elemental ratio, a species-specific correlation was identified between lake water, otolith, fin spine and gill tissue samples. The best discrimination between fish species was achieved using a Na/Ca versus Mg/Ca elemental ratio diagram of gill tissues. The best discrimination between fish from different lakes was achieved using a Ba/Mg versus Sr/Mg elemental ratio diagram for fin spine tissue.
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The formation of continents involves a combination of magmatic and metamorphic processes. These p... more The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T) conditions of (ultra) high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones (high-pressure metamorphic setting), and vertically by accumulation of mantle-derived magmas at the base of the crust (high-temperature metamorphic setting). Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H 2 O-activity fluids including high-density CO 2 and concentrated saline solutions (brines). These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust. This accumulation causes tectonic instability, which together with the heat input from the sub-continental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation. Ó 2015, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
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Miner Mag, 1994
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Journal of African Earth Sciences, 1999
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Computers & Geosciences, 2005
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Comptes Rendus Geoscience, 2012
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Gems & Gemology, 1998
This article presents, for the first time, both gemological and geologic infor-mation on topaz, a... more This article presents, for the first time, both gemological and geologic infor-mation on topaz, aquamarine, and other beryls from miarolitic peg-matites at Namibia's historic Klein Spitzkoppe mineral locality. Topaz from Klein Spitzkoppe was first reported more than 100 years ago, ...
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Geological Society of America Memoirs, Feb 1, 2011
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Water Sa, Jul 1, 2011
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Gondwana Research, 2012
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Geoscience Frontiers, 2014
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Geological Society of America Memoirs, 2011
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Journal of African Earth Sciences, Feb 1, 1999
Starting from the hypothesis that the lower continental crust is dominated by granulites, some es... more Starting from the hypothesis that the lower continental crust is dominated by granulites, some essential features of granulites are recalled. Two general P-T-t paths are possible, clockwise and anticlockwise, of which the former is more common for high pressure granulites, the latter for low pressure granulites. For high temperature, low pressure granulites, granulite metamorphism appears to be a discrete event, caused by a sudden temperature increase in a more or less thickened crust. The complex granulite chemistry, characterised by the possible mobility of some elements (LILE, Ti), as well as the P-T-t evolution, are explained by two complementary mechanisms operating simultaneously in different domains and at a variable scale: fluid-absent melting and fluid-assisted metamorphism (high salinity aqueous fluid and high density CO 2 fluid). CO 2 is brought into the lower crust by mantle-derived magmas, which also supply the required heat, whereas the high salinity aqueous fluid is probably derived from internal crustal sources. The size of Precambrian granulite provinces, the geodynamic setting, and the chemical composition of syn-metamorphic intrusions, do not suggest a direct relation with subduction processes. This paper favours a model of intraplate extension without rupture, ultimately leading to a vertical accretion of the continent by the incorporation of mantle-derived magmas at the base of the crust.
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Papers by Jan Marten Huizenga