Cargill Township carbonatite complex, District of ... - Geology Ontario

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CARBONATITE - ALKALIC ROCK COMPLEXES: CARGILL TOWNSHIP placed on obtaining samples from the more homogeneous cores, or sections of core which could be considered to be most representative of the lithologies pre sent. The diamond drill core of Kennco Exploration (Canada) Limited is still at the property; however, the numbers on the core boxes are unreadable due to weathering. The original version of this study was prepared in 1978. Brief summaries of the conclusions or results of more recent studies (e.g. Twyman 1983, Kwon 1986 and Sharpe 1987) have been added to this study, but no major rewriting has been done. Similarly, the results of exploration work from 1981 to 1987, supplied to the author by Sherritt Gordon Mines Limited, have been consulted to revise the exploration history and geology on the carbonatite complex. Laboratory Technique A suite of the texturally and compositionally most homogeneous rocks was se lected for thin sectioning and chemical analysis. The thin sections were examined only briefly and the major textural features noted. These observations are sum marized in Table A-1 in Appendix A. Allen (1972) presented detailed micro probe analyses of the various mineral phases, some of which is reproduced here in Appendix B. Nomenclature The author uses names for the mafic to ultramafic rocks in the conventional manner. The following terms are used to describe the carbonatite rocks. Sovite: A carbonatite rock containing 509c or more calcite. Various mineralogic modifiers are used to classify the sovite. Rauhaugite: The dolomitic equivalent of sovite. Silicocarbonatite: A carbonatite rock composed of 5096 or more oxide and silicate minerals. Where the silicate mineralogy exceeds 9096 various other rock names are applied, i.e., ijolite, biotitite, pyroxenite, etc. The definitions of sovite and Silicocarbonatite are modified from Heinrich (1966, p. 12). The author has found Heinrich's subdivision of the carbonate-rich carbonatitic rocks generally suitable for field use when modified to a two-fold subdivision at about 5096 oxide and silicate mineral contents. The two-fold subdi vision is more convenient than the four-fold subdivision of Heinrich (1966, p. 12) because carbonatites are extremely variable in mineral content over distances of less than a few centimetres. It is difficult to rigorously classify such heterogeneous rocks and they are not mappable at any convenient map scale.
General Geology The Cargill Township Carbonatite Complex (Table l, Figure 2 and Figure 3, Chart A, back pocket), as interpreted from ODM-GSC aeromagnetic map 2252G, is a dumbbell-shaped body approximately 7.2 km long consisting of two pronounced aeromagnetic anomalies separated by a narrow band of lower aeromagnetic intensity. The two pronounced aeromagnetic anomalies have been interpreted as being the faulted portions of a once continuous, more circular body (Bennett et al. 1967; Sandvik and Erdosh 1977). The International Minerals and Chemical Corporation (Canada) Limited has named these two anomalies the north and south subcomplexes respectively, while a third aeromagnetic anomaly (see Figure 2) 4 km west of the main intrusive mass was named the west sub- complex (Sandvik and Erdosh 1977). The Cargill Township complex is enveloped in Early Precambrian quartz dio rite gneiss and amphibolite (Sandvik and Erdosh 1977). Drilling by the Interna tional Minerals and Chemical Corporation (Canada) Limited indicates that the complex consists of arcuate to curvilinear bands of siderite, calcite, and dolomite carbonatite enclosed in a wide unit of pyroxenite and hornblendite (Sandvik and Erdosh 1977). The carbonatite is multi-phased and zoned. The outer zone of carbonate rock is calcite carbonatite and the core is dolomite carbonatite (Sandvik and Erdosh 1977). Siderite phases, which are probably the latest, in- TABLE 1. TABLE OF LITHOLOGIC UNITS FOR THE CARGILL TOWNSHIP CARBONATITE COMPLEX. MESOZOIC TO CENOZOIC Recent Swamp and stream deposits. Pleistocene Glacial lake clays. Unconformity Late Cretaceous to Early Tertiary Pre-glacial quartz sands, organic clay, and kaolinite. Apatite-rich residuum. Unconformity Unconformity MIDDLE PRECAMBRIAN (PROTEROZOIC) Cargill Tp. Carbonatite Complex Sovite, rauhaugite, sideritic carbonatite; silicocarbonatite. Intrusive Contact Pyroxenite, hornblendite, and related rocks. Intrusive Contact EARLY PRECAMBRIAN (ARCHEAN) Quartz diorite gneiss; amphibolite.
Page 1 and 2: THESE TERMS GOVERN YOUR USE OF THIS
Page 3 and 4: Ontario Geology of Ministry of Mine
Page 5: Foreword The Cargill Township Carbo
Page 8 and 9: TABLES 1. Table Of Lithologic Units
Page 11 and 12: Geology of Carbonatite - Alkalic Ro
Page 13 and 14: Introduction The Cargill Township C
Page 15: R. P. SAGE Township and extends int
Page 19 and 20: R. P. SAGE A crandallite-rich blank
Page 21 and 22: R. P. SAGE more euhedral when in co
Page 23 and 24: Other Mafic to Ultramafic Rocks R.
Page 25 and 26: R. P. SAGE p. 116) as a mixture of
Page 27 and 28: R. P. SAGE cores to magnesio-arfved
Page 29 and 30: R. P. SAGE mined thickness. Sandvik
Page 31 and 32: TABLE 2. STRATIGRAPHY OF OVERBURDEN
Page 33 and 34: R. P. SAGE containing approximately
Page 35 and 36: INTERNAL STRUCTURES R. P. SAGE The
Page 37 and 38: Economic Geology The Cargill Townsh
Page 39 and 40: R. P. SAGE Thoburn (1984) prepared
Page 41 and 42: Appendix A Petrographic Description
Page 43 and 44: R. P. SAGE Clinohumite is anhedral
Page 45 and 46: R. P. SAGE with brown cores and red
Page 47 and 48: R. P. SAGE hedral grains disseminat
Page 49 and 50: R. P. SAGE pyroxene and occurs alon
Page 51 and 52: R. P. SAGE grains disseminated thro
Page 53 and 54: TABLE A-2. MAJOR ELEMENT ANALYSES (
Page 55 and 56: TABLE A-2. CONTINUED. Ref. No. SiO2
Page 57 and 58: TABLE A-2. CONTINUED. Ref. No. SiO2
Page 59 and 60: R. P. SAGE TABLE A-3. TRACE ELEMENT
Page 61 and 62: TABLE A-3. CONTINUED. Ref. No. Ag A
Page 67 and 68:
TABLE A-3. CONTINUED. Ref. No. Ag A
Page 69 and 70:
TABLE A-3. CONTINUED. Ref. No. Ag A
Page 71 and 72:
TABLE A-4. CONTINUED. Ref. No. QZ C
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
R.P. SAGE TABLE A-5. AVERAGE CHEMIC
Page 83 and 84:
Appendix B — Electron Microprobe
Page 85 and 86:
R.P. SAGE TABLE B-2. MICROPROBE MIN
Page 87 and 88:
R. P. SAGE TABLE B-3. MICROPROBE MI
Page 89 and 90:
TABLE B-5. MICROPROBE MINERAL ANALY
Page 91 and 92:
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Page 95 and 96:
Page 97 and 98:
References Allen, C. 1972: The Petr
Page 99 and 100:
Index Aeromagnetic data, 7, 21, 24
Page 101 and 102:
Kinking Biotite, Rauhaugite, 18 Phl
Page 103:
Chart A — Cargill Carbonatite Com
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Cargill Township carbonatite complex, District of ... - Geology Ontario

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