Paleogeology

Paleogeology, Paleoclimate, in relation to Evolution of Life on Earth

geomorphology lithology Slave Craton 1


Cleaned exposures of the Acasta gneisses at their discovery site. Ancient tonalites (4.03 Ga) occur on left side of the picture, and are intruded by highly deformed younger granite sheets and mafic dykes. A. Cleaned exposures of the Acasta gneisses at their discovery site. Ancient tonalites (4.03 Ga) occur on left side of the picture, and are intruded by highly deformed younger granite sheets and mafic dykes.
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Basal quartzites of the Central Slave Cover Group overlying basement of the Central Slave Basement Complex. Low foreground to the right are low-weathering basement gneisses; dark ridge in background are ca. 2.7 Ga basalts overlying the quartzites.B. Basal quartzites of the Central Slave Cover Group overlying basement of the Central Slave Basement Complex. Low foreground to the right are low-weathering basement gneisses; dark ridge in background are ca. 2.7 Ga basalts overlying the quartzites.
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B. Typical 2.95 Ga foliated tonalites of the Central Slave Basement Complex with transposed 2734 Ma mafic dykes.
C. Syn-Kam Group quartz-porphyritic tonalite intrusion (ca. 2713 Ma), silling into the northern part of the Yellowknife greenstone belt (geologist Val Jackson for scale). The large sill-like body is cut by somewhat younger mafic dykes that likely fed the upper part of the greenstone belt. Inset shows close-up of altered quartz-porphyritic tonalite.
Syn-Kam Group quartz-porphyritic tonalite intrusion (ca. 2713 Ma), silling into the northern part of the Yellowknife greenstone belt (geologist Val Jackson for scale). The large sill-like body is cut by somewhat younger mafic dykes that likely fed the upper part of the greenstone belt. Inset shows close-up of altered quartz-porphyritic tonalite.
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Quartz porphyritic rhyolite breccia with carbonate matrix, typical for the uppermost part of 2690-2660 Ma felsic volcanic edifices. D. Quartz porphyritic rhyolite breccia with carbonate matrix, typical for the uppermost part of 2690-2660 Ma felsic volcanic edifices.


E. Massive sulphide mineralization of the Sunrise deposit, associated with ca. 2670 Ma felsic volcanic rocks just below the interface with the Burwash Formation turbidites.
Massive sulphide mineralization of the Sunrise deposit, associated with ca. 2670 Ma felsic volcanic rocks just below the interface with the Burwash Formation turbidites.
G. Syn-Kam Group K-feldspar porphyritic granodiorite pluton in basement below greenstone belts.
F. Thickly bedded sandy turbidites typical of the Burwash Formation in its type area east of Yellowknife. The oblique areal photo shows an F1 syncline refolded by north-northwest trending F2 folds.
Thickly bedded sandy turbidites typical of the Burwash Formation in its type area east of Yellowknife. The oblique areal photo shows an F1 syncline refolded by north-northwest trending F2 folds.








K.	Aerial photo of large scale, upright, fold structures in turbidites of the Yellowknife structural basin. K. Aerial photo of large scale, upright, fold structures in turbidites of the Yellowknife structural basin.










E. banded iron formation
& D. fuchsitic quartzite,
& C. Basal quartz pebble conglomerate
of the Central Slave Cover Group that overlies the basement complex.






I. Carbonate-cemented rhyolite breccia typical for the younger volcanic cycle.

















H. Polymict conglomerate, including 10-30 cm granitoid cobbles, which occurs locally at the base of the younger, 2.69-2.66 Ga, volcanic cycle.


F. Variolitic pillow basalts of the Kam Group, Yellowknife.











L. Late-tectonic conglomerates, <2600 Ma, unconformably overlying unroofed granitoid rocks, Point Lake.


G. Silicate facies iron formation interlayered with turbiditic greywackes, George Lake, northeastern Slave. This banded iron formation hosts significant epigenetic gold mineralization.



M. Late-tectonic, 2585 Ma, K-feldspar megacrystic granite of the Morose Suite in the core of the domal Sleepy Dragon Complex; inset shows 1-2 cm-large K-feldspar megacrysts.






I. Dense Proterozoic mafic dyke swarms cutting extended Slave crust and its cover














satellite image courtesy of NASA, all images of geomorphologic features and lithology courtesy of Natural Resources Canada (source website)

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