A new class of mélange and its bearing on early earth tectonics, the Mesoarchean Fiskenæsset region, southern West Greenland
Polat A, Kusky T, Windley B, Sotiriou P (2026)
Publication Type: Journal article, Review article
Publication year: 2026
Journal
Book Volume: 278
Article Number: 105527
DOI: 10.1016/j.earscirev.2026.105527
Abstract
The contiguous Mesoarchean Fiskenæsset and Bjørnesund regions in southern West Greenland display excellent exposures and are some of the best mapped Archean terrains in the world, providing an excellent opportunity to test the geodynamic models proposed for the growth of Archean continental crust. The Fiskenæsset region consists of tectonically imbricated TTG (tonalite-trondhjemite-granodiorite) gneisses, basalts, lithologies of the Fiskenæsset Anorthosite Complex, and minor pelitic sedimentary rocks. This rock association is called the Fiskenæsset litho-tectonic assemblage. The assemblage displays a block-in-matrix structure, with thousands of tectonic fragments of basalt, gabbro, leucogabbro, anorthosite, peridotite, and metapelitic sedimentary rocks that occur as trains of inclusions within mylonitic thrust faults in a foliated TTG matrix, representing a Mesoarchean tectono-magmatic-metamorphic mélange complex. In this respect, it is a new type of mélange complex, that we name the Fiskenæsset agmatitic mélange . The anorthosite complex originated from a hydrous mantle source and was emplaced into the basalts that formed at a back-arc spreading center. The mélange formed in a subduction zone that we propose developed in response to the collapse of the back-arc basin. The protoliths of the syn-tectonic TTG gneisses were emplaced along low-angle thrust faults during deformation and were derived from partial melting of subducted oceanic crust. After the mélange formation, the assemblage underwent three phases of shortening deformation resulting in the development of regional-scale isoclinal and nappe-like recumbent folds. The Fiskenæsset subduction-accretion complex is structurally overlain to the south-southeast by the coeval Bjørnesund litho-tectonic assemblage, consisting mainly of TTG gneisses, granite, pillow basalt, andesite, dacite, pyroclastic volcanic rocks and pelitic sedimentary rocks with island arc geochemical signatures. The Fiskenæsset and Bjørnesund litho-tectonic assemblages together represent a paired subduction-accretion complex and arc-fore-arc system.
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APA:
Polat, A., Kusky, T., Windley, B., & Sotiriou, P. (2026). A new class of mélange and its bearing on early earth tectonics, the Mesoarchean Fiskenæsset region, southern West Greenland. Earth-Science Reviews, 278. https://doi.org/10.1016/j.earscirev.2026.105527
MLA:
Polat, Ali, et al. "A new class of mélange and its bearing on early earth tectonics, the Mesoarchean Fiskenæsset region, southern West Greenland." Earth-Science Reviews 278 (2026).
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