Jessie Lake Property - Geology Ontario

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CU-NI-PGE MINERALIZATION IN ASSOCIATION WITH THE TEMAGAMI ISLAND LEUCOGABBRO, A LATE ARCHEAN/EARLY PROTEROZOIC LAYERED INTRUSION, TEMAGAMI, ONTARIO Fitzhenry,K.L. , Dunning,J. K . , James,R.S., Gibson,H.L., Laurentian University, Sudbury, Ontario, P3E 2C6, Lane,T.E., Teck Exploration Ltd., l First Place, Toronto, Ontario, M5X 1G9, Keays, R.R., Laurentian University, Sudbury, Ontario, P3E 2C6. The Temagami Island Leucogabbro (TILG) forms a conformable si 11-like intrusion 30 km long and 1.0-1.5 km thick within a late Archean greenstone sequence. Its lower contact with intermediate/felsic flows and heterolithic volcanic breccias dips at 70 0 ; its upper contact with mafic greenstones is unexposed and unconformably overlain by Gowganda Formation metasediments of the Huronian Supergroup {circa 2.4 Ga) . A zone of pyritic mineralization occurs discontinuously at the base of the TILG and where the pyrite zone is thickest (10-20m), high-grade Cu(Zn-Ni-PGE) ore zones occur in the underlying footwall volcanic rocks. The most complete stratigraphic section of the sill occurs at the Temagami Mine, where Cu-rich ore zones were mined from 1955-1970. The lower 300m of the sill is composed of 10 cyclic units each consisting of a basal gabbro and upper leucogabbro. The upper 60-70 percent of the sill consists of several cycles of weakly layered magnetite gabbro that grades upwards into quartz gabbros. Pervasive greenschist alteration has completely replaced primary mineral compositions but textural features permit an estimate of primocryst phases. In the lower third of the sill, plagioclase +/- pyroxene and olivine form primocrysts in the gabbros of each cycle; plagioclase is the sole primocryst in the leucogabbro. Both plagioclase and V-rich magnetite are liquidus phases in the magnetite gabbros; in the quartz gabbros, quartz is an interstitial phase; in neither of these rock types is a mafic primocryst phase recognized. Chlorite normally replaces interstitial (occaisionally poikiolitic) pyroxene throughout the sill. Within metres of the contact between the lower and upper portions of the sill a rapid decrease in grain size coupled with a sharp discontinuity in primocryst phases suggests that these two zones represent different magma pulses and compositions. Sulphide mineralization within the sill occurs only in the 20-30m thick gabbro that forms the basal portion of the first cyclic unit above the Pyrite Zone. Pyrite, chalcopyrite and minor pyrrhotite +/- magnetite occur as 2-3 cm disseminated blebs and as patches up to l m in diameter within the metagabbro assemblage ab-chl-mu-qz-ankerite-lx. The percentage of sulphide increases downwards to as much as 10-20 modal percent at the base of this cyclic unit where it is in contact with the Pyrite Zone. The Pyrite Zone occurs as discontinuous lenses up to 20 m thick at the contact between the TILG and footwall volcanic rocks. At Temagami Mine its stike length is 1.5 km; mining activities indicate its downdip extension is not greater than 300m. In one well exposed outcrop area a crude stratigraphy for this zone is recognised which from the footwall
upwards consists of: a)irregular shaped pods of massive pyrite * chalcopyrite (and minor millerite, seigenite, gersdorffite and magnetite) up to several metres in diameter, enclosed in fine grained anorthositic gabbro (now altered to Fe chlorite and quartz); b)a zone of leucogabbro with interstitial sulphide (py+cpy) - Fe chlorite has replaced the silicate assemblage; and c)a 3 m thick unit of leucogabbro/gabbro composed of plagioclase +/- pyroxene (both now replaced by a chlorite-carbonate assemblage), coarse poikilitic Fe-Ti oxide (now leucoxene), and minor disseminated pyrite*chalcopyrite. For this zone Ni+Cu = 1.35 wt *; typical Cu/Ni =l.9Q, and limited PGE data indicate that Pt+Pd = 150 ppb and Pt/Pt + Pd = 0.25. We believe the Pyrite Zone formed due to the intrusion of a leucogabbro-sulphide magma along the basal contact of the TTLG. The high-grade massive Cu (Zn-Ni-PGE) sulphide mineralization of the Temagami Copper Mine occurs 10 to 50 m below the base of the Pyrite Zone. The ore zones occur as irregularly-shaped pods and lenticular vein-like zones typically 5x20x40 m in size, either entirely within heterolithic volcanoclastic breccias and/or at the contact of this rock type with intermediate to felsic flows, and conformable to the volcanic stratigraphy. The mineralization is comprised mainly of chalcopyrite with lesser amounts of pyrite. Minor amounts of sphalerite, millerite, gersdorffite, ramelsbergite, tetrahedrite and galena are also present and disseminated magnetite is common. The PGM 1 s identified to date include temagamite, merenskyite, hessite, naumonite, tsumoite and testbiopalladite. Gangue minerals include ferroan dolomite, calcite, quartz, Fe chlorite and monazite. The volcanic rocks that host the sulphide mineralization have been altered to assemblages containing combinations of sericite, ferroan carbonates, chlorite and tourmalinization as a result of premineralization regional events. Only narrow chlorite alteration selvages are directly related to the sulphide mineralization in the footwall volcanic rocks. We initated this study to test the hypothesis that the volcanichosted, Cu-rich, PGE-bearing footwall ore zones represent remobilized sulphide (via magmatic and/or hydrothermal processes) derived from an Fe-Cu-Ni-PGE sulphide zone that initially formed at the base of the TILG in an environment similar to the deep Cu mineralizatin at Sudbury. In general terms, the results of our study to date support this hypothesis.
Page 1 and 2: 31M04SW2026 2.18913 STRATHCONA 010
Page 3 and 4: Figure 5 Figure 6 Claim Map (Back P
Page 6 and 7: X Ontario Quebec Cochrane Larder La
Page 8 and 9: Geology: Briefly, the Jessie Lake P
Page 10 and 11: (See Appendix C for Sample Descript
Page 12 and 13: References Bennett, G. 1978: Geolog
Page 14 and 15: Resources Corporation from Gino Chi
Page 16 and 17: JESSIE LAKE PROPERTY Strathcona Tow
Page 18 and 19: Food: 122.52 McDonalds S 4.03 Busy
Page 20 and 21: Rick Lindsay: Sept 21, 22, 23, 24/9
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Page 26 and 27: OCCURRENCES OF TOURMALINIZATION IN
Page 28 and 29: Jessie Lake Property Redstar Resour
Page 30 and 31: Established 1928 Swastika Laborator
Page 32 and 33: Ontario Mimstty of NoiUiom Uevelopi
Page 34 and 35: i 5. Work to be recorded and distri
Page 36 and 37: ® Ontario Ministry ot Northern Dev
Page 38 and 39: Work Report Assessment Results Subm
Page 40 and 41: Distribution of AssGssrnGnt Work Cr
Page 42 and 43: 27189 l 3 K3J* A^H -X' \C~^~r s*' y
Page 44 and 45: 2.18913 Redstar Resources Corporati
Page 46 and 47: Legend Symbols and Abbreviations Ge
Page 48: 1230666 2 2 O l 4 S 12306 47251 P8I

Jessie Lake Property - Geology Ontario

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