Paleoproterozoic volcanogenic massive sulfide mineralization, Karrat Group, Central Kangiusap Kuua, West Greenland

M DeWolfe, Jochen Kolb, D Rosa

Publikation: KonferencebidragAbstract ved konferencepeer review

Abstrakt

The Karrat Group of Central West Greenland is composed of the Qeqertarssuaq (Lower Karrat Group), Qaarsukassak, Mârmorilik, Kangilleq, and Nûkavsak formations (Upper Karrat Group). All volcanic rocks of the Karrat Group are placed in the Kangilleq formation (informal), which is defined as a package of meta-volcanic (greenschist) rocks that unconformably overlie meta-sedimentary rocks of the Qeqertarssuaq Formation and are conformably overlain by meta-sedimentary rocks of the Nûkavsak Formation. The Kangilleq formation shows dominantly within-plate, alkali basalt geochemical signatures.

A unique sequence of meta-volcanic rocks (~100 m) occurs in the Central Kangiusap Kuua. These rocks differ from all other rocks of the Kangilleq formation in that they: 1) show tholeiitic arc-like affinities; 2) contain felsic volcanic rocks; and 3) contain VMS-type sulfide mineralization. The basal ~60 m consist of pillow basalt lava containing flow top breccias and hyaloclastite indicating subaqueous eruption. Overlying the pillows is an ~30 m sequence of mafic volcaniclastic rocks where normal to reverse grading, massive to crudely bedded, and channel/scour structures suggest emplacement by mass debris flows. The mafic volcaniclastic beds are overlain by a rhyolite breccia ~5 m), which is capped by a strongly silicified rock (~2 m). The felsic breccia hosts stringer to massive sulfide (pyrite, pyrrhotite ± sphalerite, chalcopyrite).

Our work documents the first occurrence of a tholeiitic, bi-modal volcanic sequence with arc-like signature, and VMS-type mineralization within the Karrat Group. Thus, it has important implications for mineral exploration, and the interpretation of the geodynamic setting of the Kangilleq formation.
OriginalsprogEngelsk
StatusUdgivet - 2018
BegivenhedNordic Geological Winter Meeting 2018 - Copenhagen
Varighed: 10 jan. 201812 jan. 2018

Konference

KonferenceNordic Geological Winter Meeting 2018
ByCopenhagen
Periode10/01/1812/01/18

Programområde

  • Programområde 4: Mineralske råstoffer

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