Transition between “Archaean-type” and “modern-type” tectonics: Insights from the Finnish Lapland Granulite Belt

Cagnard, Florence; Barbey, Pierre; Gapais, Denis

doi:10.1016/j.precamres.2011.02.007

Cited by 77 publications

(45 citation statements)

References 68 publications

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“…Condie, 1989;Taylor and McLennan, 1985;Cagnard et al, 2011;Keller and Schoene, 2012). During this period, the Earth's continental crust experienced a pronounced compositional change, with the transition from Archean sodic granitoids forming the socalled tonalite-trondhjemite-granodiorite (hereafter TTG) series (Jahn et al, 1981) to medium and high potassium granitoid composititions which define granite-granodiorite series dominating the late-to post-Archean granitoid record (Martin et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

The Neoarchean transition between medium- and high-K granitoids: Clues from the Southern São Francisco Craton (Brazil)

Farina

Albert

Lana

2015

Precambrian Research

125

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Section: Introductionmentioning

confidence: 99%

The Neoarchean transition between medium- and high-K granitoids: Clues from the Southern São Francisco Craton (Brazil)

Farina

Albert

Lana

2015

Precambrian Research

125

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“…Thus, this study contributes to a growing body of research pointing to a distinct style of deformation and metamorphism in Neoarchean and Paleoproterozoic orogens (e.g., Cagnard, Barbey, & Gapais, ; Cagnard, Durrieu, Gapais, Brun, & Ehlers, ; Chardon, Gapais, & Cagnard, ; Gapais, Cagnard, Gueydan, Barbey, & Ballèvre, ; Rey & Coltice, ; Rey & Houseman, ). Li and Wei () concluded that the UHT metamorphism might have occurred over a much wider area than that suggested from the UHT rocks with diagnostic indicators (Guo et al., ; Santosh Tsunogae, et al., ), which is consistent with the newly discovered UHT pelitic granulites in the Helanshan complex.…”

Section: Discussionmentioning

confidence: 79%

Ultrahigh‐temperature metamorphism in the Helanshan complex of the Khondalite Belt, North China Craton: Petrology and phase equilibria of spinel‐bearing pelitic granulites

Gou

Liu

et al. 2018

Journal Metamorphic Geology

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To better understand the formation of ultrahigh‐temperature (UHT) metamorphic rocks, we present a detailed petrological study of the recently discovered spinel‐bearing garnet–sillimanite granulites in the Helanshan complex of the Khondalite Belt in the North China Craton. In calculated P–T pseudosections, isopleths of grossular content in the peak assemblage field of garnet+K‐feldspar+sillimanite+spinel+ilmenite+quartz+melt suggest that the metamorphic peak occurred at ∼960–1,030°C and 6.3–7.3 kbar. Using ternary feldspar thermometry, a minimum temperature limit of the peak metamorphic conditions is calculated to be ∼910–955°C at 6.5 kbar, with a weighted mean of ∼940°C. Thus, all these results point to a very steep geothermal gradient well into the UHT field. In addition, a clockwise P–T evolution is determined, which involves pre‐Tmax decompression followed by nearly isobaric cooling. Based on these newly discovered UHT pelitic granulites, which do not contain index minerals typically considered diagnostic of UHT metamorphism, and the high‐P pelitic granulites exposed in the Helanshan and Qianlishan complexes, we propose that the Khondalite Belt is an ultrahot metamorphic orogen formed by collision between the Yinshan and Ordos Terranes. The style of this continental collision was rather different from Phanerozoic collisions, but was similar to the two‐sided hot collision model during the Proterozoic. Two‐sided hot collision involves shallow slab breakoff during collision, which leads to extension and the development of a wide plateau‐like orogen, which is underlain by melt‐bearing mantle that maintains a hot environment at the collision zone.

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“…The Mäkärä region within the Tana Belt consists of Archean gneiss (3.1-2.6 Ga) and Paleoproterozoic supracrustal rocks (2.3-2.0 Ga), which were thrusted together with the Lapland Granulite Belt onto the Central Lapland Greenstone Belt at c. 1.9 Ga during the Svecofennian orogeny [42][43][44]. The bedrock of the study area is poorly exposed, and largely covered by saprolite, weathered regolith and Quaternary till with variable thicknesses, as well as with dense vegetation.…”

Section: The Mäkärä Vaulo Area In the Tana Beltmentioning

confidence: 99%

Geology and Mineralogy of Rare Earth Elements Deposits and Occurrences in Finland

et al. 2018

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Rare earth elements (REE) have critical importance in the manufacturing of many electronic products in the high-tech and green-tech industries. Currently, mining and processing of REE is strongly concentrated in China. A substantial growth in global exploration for REE deposits has taken place in the recent years and has resulted in considerable advances in defining new resources. This study provides an overview of the mineralogical and petrological peculiarities of the most important REE prospects and metallogeny of REE in Finland. There is a particularly good potential for future discoveries of carbonatite hosted REE deposits in the Paleozoic Sokli carbonatite complex, as well as in the Paleoproterozoic Korsnäs and Kortejärvi Laivajoki areas. This review also provides information about the highest known REE concentration in the alkaline intrusions of Finland in the Tana Belt and other alkaline rock hosted occurrences (e.g., Otanmäki and Katajakangas). Significant REE enrichments in hydrothermal alteration zones are also known in the Kuusamo Belt (Uuniniemi and Honkilehto), and occurrences of REE-rich mineralisation are also present in granite pegmatite bodies and greisens in central and southern Finland (Kovela monazite granite and the Rapakivi Granite batholith at Vyborg, respectively). REE minerals in all of the localities listed above were identified and analyzed by scanning electron microscopy (SEM) and electron microprobes (EMPs). In localities of northern and central Finland, both primary rock forming and epigenetic-hydrothermal REE minerals were found, namely phosphates (monazite-Ce, xenotime-Y), fluorcarbonates (bastnäsite-Ce, synchysite), and hydrated carbonates (ancylite-Ce), hydrated aluminium silicates (allanite-Ce, Fe-allanite, cerite, chevkinite), oxides (fergusonite, euxenite) and U-Pb rich minerals. The chondrite normalized REE concentrations, the La/Nd ratios and the REE vs. major element contents in several types of REE bearing minerals from prospects in Finland can be used to identify and define variable REE fractionation processes (carbonatites), as well as to discriminate deposits of different origins.

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Transition between “Archaean-type” and “modern-type” tectonics: Insights from the Finnish Lapland Granulite Belt

Cited by 77 publications

References 68 publications

The Neoarchean transition between medium- and high-K granitoids: Clues from the Southern São Francisco Craton (Brazil)

The Neoarchean transition between medium- and high-K granitoids: Clues from the Southern São Francisco Craton (Brazil)

Ultrahigh‐temperature metamorphism in the Helanshan complex of the Khondalite Belt, North China Craton: Petrology and phase equilibria of spinel‐bearing pelitic granulites

Geology and Mineralogy of Rare Earth Elements Deposits and Occurrences in Finland

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