Petrographie de la matiere organique et assemblages des mineraux des argiles du district minier et de la region de Pine Point, Canada : une caracterisation des anomalies associees aux gites

Abstract 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 on compare les temperatures d'homogeneisation (Th = 100°C) des inclusions fluides de la sphalerite et des dolomites associees & la mineralisation aux temperatures estimees a partir de la reflectance de la collinite (84°C a 117°C), Ton ne peut pas conclure a la presence d'une anomalie ther-mique dans le district minier de Pine Point. De plus, la reflectance des organoclastes n'est pas plus ; elevee dans le district minier de Pine Point que dans les localites plus eloignees des gites. L'analyse des mineraux argileux conduit & la meme conclusion : aucune anomalie thermique n'est decelable dans les unites echantillonnees a I'interieur du district minier de Pine Point quelque soil 1'indicateur utilise.
La kaolinite et la matiere organique alteree, affichant des valeurs anomales de sa reflectance, se trouve essentiellement en presence de soufre et de sulfures. Cela suggere une origine authigene de la kaolinite et une alteration de la matiere organique reliees au phenomenes de mineralisation.
Abstract — The alteration of organic matter and clays is studied in the Devonian Pine Point Formation carbonate muds, "F" facies, and its lateral equivalents the Evie Formation and the bituminous unit at the base of the Horn River Formation. The organic matter is mainly composed of solid bitumen with few fossil fragments (organoclasts). Most samples contain only illite and mixed layer illite/smectite.
If we compare the Th(100°C) from fluid inclusions of sphalerite and dolomites associated with mineralization to the temperatures calculated from the reflectance (Ro) of the collinite (84°C to 117°Q, we cannot detect a thermal anomaly in the Pine Point mining district. This result is based on the reflectance values of organoclasts from the mining district that are not higher than those reflectancevalues measured on organic matter (OM) away from the ore deposit. A similar conclusion is reached from the clay study: none of the parameters used allow us to identify a thermal anomaly in the samples from the mining district.
The kaolinite and the altered OM showing anomalous Ro values mainly occur with sulfides and sulfur. This association suggests an authigenic origin for the kaolinite and an alteration of the OM due to the mineralization events.
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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 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...
Publication: Exploration & Mining Geology
Author(s): M.B. McCLENAGHAN
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: 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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