Showing papers in "Ore Geology Reviews in 1998"

TL;DR: The orogenic gold deposits were formed during compressional to transpressional deformation processes at convergent plate margins in accretionary and collisional orogens as discussed by the authors, with gold deposition from 15-20 km to the near surface environment.

TL;DR: The majority of lode gold deposits formed proximal to regional translithospheric terrane-boundary structures that acted as vertically extensive hydrothermal plumbing systems; the structures record variably thrust, and transpressional-transtensional displacements as mentioned in this paper.

TL;DR: In this paper, SHRIMP U-Pb studies of complexly zoned zircons of the Linglong, Luanjiahe and Guojialing granitoid suites suggest that the Jiaodong Peninsula is underlain by Precambrian basement with components up to 3.4 Ga old.

TL;DR: In this paper, it was shown that gold would have been transported as Au(HS)2− over a substantial range in metamorphic conditions and crustal depth, and that gold transport in the ore fluids that formed some diopside- and diop-side-K-feldspar class deposits (T>550°C) would be as AuCl2−, whereas the Au (HS)° complex may have been significant in some of the lower temperature (≤270°C), less alkaline ore fluids.

TL;DR: In this article, the authors explored fault-fracture mesh structures for mesozonal gold-quartz vein systems in the bendigo-ballarat zone of the Paleozoic Lachlan Fold Belt in Australia and the Mesozoic Otago Schists in New Zealand.

TL;DR: More than 420 million oz of gold were concentrated in circum-Pacific synorogenic quartz lodes mainly during two periods of continental growth, one along the Gondwanan margin in the Palaeozoic and the other in the northern Pacific basin between 170 and 50 Ma.

TL;DR: In this paper, empirical geochemical links between felsic volcanism, geotectonic environment, and extensional geodynamics have not been adequately documented so as to distill the fundamental relationships between these features and formation of volcanic-hosted massive sulphide (VHMS) mineralization.

TL;DR: In this paper, 40 Ar-39 Ar data constrain the history of metamorphism, deformation and mineralization in the western subprovince of the Lachlan Fold Belt.

TL;DR: Granitoid-hosted lode gold deposits constitute a subgroup of late-Archean lode-gold deposits in the Yilgarn Craton of Western Australia as discussed by the authors.

TL;DR: The term late-orogenic, structurally-controlled gold deposits as mentioned in this paper was proposed as one which more completely encompasses the class of mineralization described in this overview, which includes a wide range of host rocks, structural settings and structural styles and alteration types.

TL;DR: In this paper, a geological-geochemical model has been developed for the formation of the sulphide deposits of Urals type, which can serve as a standard for comparative studies of the volcanogenic massive sulfide deposits in other orogenic belts.

TL;DR: In the state of Victoria, gold production has been reported to be in the order of 2.460,000 kg gold of which some 60% was sourced from extensive alluvial deposits, both of deep and shallow lead origin this article.

TL;DR: The timing relationship between metamorphic devolatilization and metamorphism at different crustal levels for different tectonic processes has been discussed in this article, where the authors discuss the genetic significance of the postmetamorphic emplacement of many gold mineralizations.

TL;DR: A review of existing information and new data strongly support the viability of studying hydrothermal alteration as a guide to turbidite-hosted mineralisation and as an indicator of the character of the solutions associated with ore deposition as discussed by the authors.

TL;DR: Although the potential use of geothermal brines for simultaneous energy and mineral production is significant, only a few mineral recovery systems are currently in commercial operation Selected metal concentrations reported in fluids and scale deposits that are of interest to economic geologists include the following Metal Fluid range, mg/kg Scale range, wt% Ag 0−14 0−89 As 0−114 0−12 Au 0−008 0−64 Cu 0−8 0−21 Zn 0−1160 0−159 Pb 0−650 0−558 Pd 0−0002 0−

TL;DR: There are over 300 gold occurrences and deposits hosted by the Cambro-Ordovician Meguma group rocks in southern Nova Scotia, Canada as discussed by the authors, which are variably deformed into upright gently to moderately doubly-plunging folds with multiple cleavages.

TL;DR: In this article, a comparison between Belgian Zn-Pb syn-diagenetic deposits and those of Germany and Ireland is performed. But the results of the comparison are limited to the Chaudfontaine stratiform deposit, which is the only recent drilling discovery.

TL;DR: Later phases of gold mineralisation throughout western and central Victoria were either temporally associated with, or post-dated the intrusion of Late Silurian to Late Devonian felsic dykes.

TL;DR: The Bendigo goldfield as discussed by the authors consists of numerous deposits located mainly along narrow, parallel-trending anticlinal domes separated by 100 to 400 m. The individual domes are part of a regional anticlinorium in Lower Ordovician sedimentary rocks.

TL;DR: Gold has played an important role in the settlement and economics of the United States as mentioned in this paper and commercial production from 24 states totaled more than 420 million troy ounces (13,000 metric tons) from 1804 through 1995.

TL;DR: The Mount Gibson gold deposits are sited at the southern tip of the Archaean Yalgoo-Singleton greenstone belt in the southern portion of the Murchison Province, Yilgarn Craton, Western Australia as discussed by the authors.

TL;DR: In this article, the authors show how some of the concepts of sequence stratigraphy can be applied in the interpretation and better understanding of known metal generative zones and in the prediction of potential host rocks of sedimentary ore deposits.

TL;DR: In the Magdala gold mine, the salinity of the fluid inclusions range from 0.7 to 8.4 wt% NaCl equivalent, suggesting that gold was deposited due to the influx of different external fluids.

TL;DR: In this paper, the principal metallogenic epochs in the Inner Zone of southwestern Japan are classified by considering mainly radiometric and microfossil age data, as follows: Early Cambrian Epoch: Characterized by podiform-type chromite deposits hosted in ophiolite complexes; these are the earliest-formed mineral deposits in the Japanese Islands, and probably formed in the shallow mantle of island-arc settings.

TL;DR: The Renabie mine in Ontario as discussed by the authors is a large-scale Au-quartz vein system with high-strain shear deformation, which is the result of inflationary vein formation by repeated increments of hydraulic fracturing and mineral deposition associated with hydrothermal fluid overpressuring within and below the ductile-brittle shear zones.

TL;DR: In this paper, the discovery of a new type of Pb-Ba deposit in a clastic complex near Monti Ferru, Sardinia, Italy is discussed with respect to source of metals and conditions of deposition, in a near-shore oxidizing and high-pH environment, as well as conditions of diagenesis and metal concentration.