A succession of near-orthogonal horizontal tectonic shortenings in the Paleoproterozoic Central Lapland Greenstone Belt of Fennoscandia: constraints from the world-class Suurikuusikko gold deposit
| Autor: | T. Niiranen, Ferenc Molnár, J. Kuva, Domingo G. A. M. Aerden, J. Välimaa, Mohammad Sayab |
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| Přispěvatelé: | Geological Survey of Finland, Academy of Finland, Ministerio de Economía y Competitividad (España), Junta de Andalucía |
| Rok vydání: | 2019 |
| Předmět: |
Arsenopyrite
010504 meteorology & atmospheric sciences Geochemistry Tectonic phase Greenstone belt engineering.material 010502 geochemistry & geophysics 01 natural sciences Precambrian Tectonics Geophysics Sinistral and dextral Geochemistry and Petrology visual_art engineering visual_art.visual_art_medium Economic Geology Pyrite Shear zone Geology 0105 earth and related environmental sciences |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | The relative and absolute timing of orogenic gold deposits in complex structural settings are active and challenging topics of research, especially in Precambrian greenstone belts. The Suurikuusikko gold deposit in Central Lapland Greenstone Belt is currently the largest primary gold producing deposit in Europe, located on a slight bend of the strike-slip Kiistala shear zone (KiSZ). Gold is refractory and locked inside arsenopyrite and pyrite. In this study, different structural features were investigated along the KiSZ from the recently stripped Etelä pit, which is the southern extension of the Suurikuusikko ore body. Our data source ranges from aeromagnetic to high-resolution aerial images, X-ray computed tomography scans of selected rock samples and regional geological and geophysical datasets. The KiSZ has recorded five discrete deformation phases, spanning between ca. 1.92 and 1.76 Ga. The refractory gold at the Suurikuusikko deposit formed during E-W contraction related to the D1 thrusting phase. This was followed by a N-S shortening event (D2), where most of the strain was taken up by the northern and southern thrusts. Tectonic vectors then switched from N-S to NE-SW and, as a result, dextral strike-slip regime (D3) commenced along the KiSZ. This event exsolved invisible gold from the sulfides and remobilized it along with fractures. A near-orthogonal switch of the regional stress regime from NE-SW to NW-SE flipped the kinematics of the KiSZ from dextral to sinistral (D4). The last deformation phase (D5) produced widespread veining under E-W contraction and secured gold mineralization at the Iso-Kuotko gold deposit within the KiSZ. Open access funding provided by the Geological Survey of Finland (GTK). This work was supported by the Academy of Finland via RAMI infrastructure project (#293109). The Academy of Finland supported “MinSysPro” (Mineral Systems and Mineral Prospectivity in Finnish Lapland) project #281670. DAwas supported by Spanish project CGL2016-80687-R and Junta de Andalucia project RNM-148. |
| Databáze: | OpenAIRE |
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