Publication Type:Book Chapter
Source:A special issue devoted to base metal and gold metallogeny at regional, camp, and deposit scales in the Abitibi greenstone belt, Economic Geology Publishing Company, Lancaster, PA, United States, Volume 103, p.1285-1308 (2008)
Keywords:Abitibi Belt, anticlines, Archean, Canada, Canadian Shield, crustal shortening, deformation, dip-slip faults, eastern canada, extension tectonics, fabric, faults, folds, foliation, gold ores, Greenstone Belts, half grabens, interpretation, kinematics, lateral faults, lineation, metal ores, metamorphic belts, mineralization, North America, oblique-slip faults, Ontario, orogeny, Precambrian, quartz veins, right-lateral faults, Strain, strike-slip faults, structural analysis, superior province, tectonics, tectonostratigraphic units, thrust faults, timiskaming group, transtension, unconformities, uplifts, veins
New structural and geochronological data and interpretations from the Timmins-Porcupine gold camp, Abitibi subprovince, more precisely define the stratigraphy and the generation, timing, and effects of deformation. Tisdale (basalts) and Porcupine (volcaniclastic and turbiditic sedimentary rocks) assemblage rocks exhibit three major foliations (S (sub 2) , S (sub 3) , S (sub 4) , plus a late constrictional fabric), of which S (sub 3) and S (sub 4) are also present in younger Timiskaming assemblage sedimentary rocks. Pre-Timiskaming folding has long been recognized in Tisdale assemblage rocks, but no foliation had previously been attributed to such an event. D (sub 1) regional uplift and extension produced a low-angle unconformity between the Tisdale and Porcupine assemblages, with partial excision of upper Tisdale stratigraphy and perhaps of the Blake River assemblage. D (sub 2) involved imbrication of a set of south-over-north thrust sheets rooted in the Porcupine-Destor deformation zone. D (sub 3) en echelon folds along the northern flank of the Porcupine-Destor deformation zone are a result of left-lateral strike-slip along this zone. The Timiskaming basin, lying along the curvilinear trace of the Porcupine-Destor deformation zone, formed as a D (sub 3) transtensional half graben, and the Dome fault formed its faulted margin. S (sub 4) foliation formed during subsequent right-lateral strike-slip movement and folding of S (sub 3) foliation. Intense D (sub 5) constrictional strain deformed earlier lineations, as the previously dilatational jog that hosts Timiskaming assemblage rocks acted as a compressional jog during right-lateral movement along the Porcupine-Destor deformation zone. These D (sub 2) to D (sub 5) phases represent an overall thrusting-strike-slip transpressional regime. There were several phases of gold mineralization in the Timmins-Porcupine gold camp. Clasts of ankerite veins occur in Timiskaming assemblage conglomerate at the Dome mine, and D (sub 3) foliation and folds crosscut early ankerite veining and alteration and some quartz veining. Thus, low-grade mineralization and possibly the quartz-fuchsite veins predate Timiskaming sedimentation. However, the bulk of gold postdates Timiskaming sedimentation. Quartz-carbonate-tourmaline-gold veins (Hollinger-McIntyre, Hoyle Pond, Dome, Aunor-Delnite mines) formed within Timiskaming assemblage and Tisdale assemblage rocks. These gold deposits developed largely as oblique slip and extensional vein arrays formed during north-south shortening and local strike-slip faulting. Younger deposits (Pamour) are associated with D (sub 4) dip-slip faulting and were weakly deformed during late D (sub 4) . Thus, the largest known Archean lode gold camp formed throughout protracted orogenesis consisting of a broadly transpressional regime with unusually well developed early thrusting.
GeoRef, Copyright 2018, American Geological Institute.<br/>2009-020490<br/>Aunor-Delnite Mine<br/>Dome Mine<br/>Hollinger-McIntyre Mine<br/>Hoyle Pond Mine<br/>Pamour Mine<br/>Porcupine-Destor Zone<br/>Timmins-Porcupine gold camp