Till Geochemistry in Areas of Thick Drift and its Application to Gold Exploration, Matheson Area, Northeastern Ontario

Abstract The Ontario Geological Survey completed a regional till sampling project between 1984 and 1988 in the Black River Matheson (BRiM) area of northeastern Ontario. The project was designed to aid mineral exploration in the area by documenting the Quaternary stratigraphy and by providing a database of till geochemistry. This paper summarizes the results from the sonic overburden drilling component of the BRiM project carried out in areas of thick drift (> 5 m). Results from till sampling in areas of thinner drift (< 5 m) have been presented in a separate paper. Approximately 1100 till samples were collected from 225 sonic drill holes. For each sample, the non-magnetic heavy mineral (>3.3 S.G.) and fine (-250 mesh) till fractions were analyzed geochemically and visible gold grains were recovered by panning.
Gold and other multi-element geochemical data were plotted using proportional symbols to highlight anomalous areas and to demonstrate how to evaluate and interpret a very large geochemical dataset. Thresholds for identifying anomalous concentrations of Au in till samples, defined using the 95th percentile, are 1500 ppb and 12 ppb for the heavy mineral and fine fractions, respectively. The heavy mineral fraction of older tills and to a lesser extent, Matheson Till, display a number of significant gold anomalies in the study area, which in a few cases, are associated with base metal anomalies. The vertical position of gold anomalies in Matheson and older tills varies from directly on bedrock to several meters above the bedrock surface and can provide information of relative ice transport distances.
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Summary: Breccias with angular and rounded clasts of a late-mineralization, "barren" hornblende ' porphyry dike set within a comminuted matrix consisting of rock fragments and quartz, cemented by quartz and K-feldspar of hydrothermal origin is observed in diamond drill cores from the Sar Cheshmeh porphyry copper deposit. Studies of age relationship between vein types, phyllic-altered clasts and the breccia groundmass suggest that the brecciation is a late event. The breccia clasts record evidence of...
Publication: Exploration & Mining Geology
Author(s): J. SHAHABPOUR
Issue: 1
Volume: 3
Year: 1994
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Summary: At True Hill in southwestern New Brunswick, low-grade porphyry-style Bi-Sn-Mo greisen mineralization is associated with the cupola of an epizonal granite porphyry (granite) that also exhibits three episodes of brecciation. The first episode of brecciation is an in situ, 8 m to 10 m wide transitional zone of net-veined to coarse-grained "blocky" endogranitic mesobreccia that is chlori-tized and greisenized and hosts weak disseminated mineralization. In a zone closer to the host rock-granite...
Publication: Exploration & Mining Geology
Author(s): DAVID R. LENTZ
Issue: 1
Volume: 3
Year: 1994
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Summary: The Magino gold mine is located 45 km northeast of Wawa, Ontario. There was limited gold production in the late thirties. The present operation was officially opened in October 1988 and produced gold until September 1992. It was a 635 tonnes per day, decline-accessed mine, with ore coming from several small blast hole and shrinkage slopes.
The host for the gold is the Webb Lake granodiorite stock which was intruded into the Goudreau Lake Deformation Zone. This east-northeast-striking...
Publication: Exploration & Mining Geology
Author(s): ANTHONY J. DEEVY
Issue: 1
Volume: 3
Year: 1994
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Summary: The Jinqingding gold deposit, situated in the east Jiaodong Peninsula of Shandong province, is typical of the pyrite-quartz vein gold deposits in the Muping-Rushan gold belt of China. The gold deposit is controlled by a great NNE fracture zone and is composed of several lenticular orebodies within the fracture zone occurring in the Kunyushan granite massif. The Kunyushan granite massif was formed by the replacement of the Archean Jiaodong group.
The main minerals associated with gold are...
Publication: Exploration & Mining Geology
Author(s): JIUHUA XU, WEIREN SUN, SHUIKU JIA
Issue: 1
Volume: 3
Year: 1994
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Summary: The Asturian fluorspar district consists of vein and stratiform deposits where mineralization is controlled by a combination of lithologjcal and tectonic factors.
It is postulated that these fluorspar deposits have been formed under disequilibrium conditions created during circulation of ascending hydrothermal solutions along faults and other high permeability conduits. Mixing of solutions is inferred from fluid inclusion studies. Cavity filling and replacement processes are very important in...
Publication: Exploration & Mining Geology
Author(s): JESUS GARCIA IGLESIAS, JORGE LOREDO
Issue: 1
Volume: 3
Year: 1994
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Summary: Cette etude porte sur I'alteration de la matiere organique et des argiles dans les boues carbonates devoniennes du facies "F" de la Formation de Pine Point et ses equivalents stratigraphiques la Formation d'Evie et 1'unite bitumineuse de la base de la Formation de Horn River. La matiere organique se compose principalement de bitume solide et de quelques fragments de fossiles (organo-clastes). La majorite des echantillons ne renferment que de 1'iDite et des interstratifiees illite/smectite.
Si...
Publication: Exploration & Mining Geology
Author(s): YVON HEROUX, ANDRE CHAGNON
Issue: 1
Volume: 3
Year: 1994
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Summary: Le gite de Pb-Zn de Gays River s'accompagne d'anomalies des proprietes de la matiere organique (MO) et des assemblages de mineraux d'argile (AMA). L'association entre la mineralisation, la distribution de la reflectance de la MO et des AMA suggere que ces traceurs peuvent servir a 1'exploration des sulfures de metaux de base dans cette region.
A l'emplacement du gite, la reflectance varie considerablement (0,8% a 1,88%), pouvant meme afficher une baisse avec 1'enfouissement, ce qui est...
Publication: Exploration & Mining Geology
Author(s): Y. HEROUX, A. CHAGNON, M.M. SAVARD
Issue: 1
Volume: 3
Year: 1994
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