Halogen and trace-element chemistry in the Gardar Province, South Greenland: Subduction-related mantle metasomatism and fluid exsolution from alkalic melts

Köhler, Jasmin; Schönenberger, Johannes; Upton, Brian; Markl, Gregor

doi:10.1016/j.lithos.2009.07.004

Cited by 49 publications

(29 citation statements)

References 101 publications

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“…High La/Nb, Ba/Nb, Zr/Nb, Sr/La, Th/Ce and Nb/Zr ratios and low Ta/La, Th/Nb, Ce/Pb (b1.0) and Th/Yb (0.23-0.51) ratios for Groups 1 and 2 are distinct from those for intraplate volcanic rocks but rather similar to those for arc volcanics ( Fig. 9a-b; e.g., Köhler et al, 2009;Nelson, 1992). Both groups have higher Ni contents than the expected range of normal primary mantle-derived melt, and plot into the field of the orogenic volcanism in the plot of Nb/Zr and Th/Zr (Fig.…”

Section: Magma Originationmentioning

confidence: 60%

Origin of paleosubduction-modified mantle for Silurian gabbro in the Cathaysia Block: Geochronological and geochemical evidence

Wang

Zhang

et al. 2013

Lithos

174

121

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Section: Magma Originationmentioning

confidence: 60%

Origin of paleosubduction-modified mantle for Silurian gabbro in the Cathaysia Block: Geochronological and geochemical evidence

Wang

Zhang

et al. 2013

Lithos

174

121

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“…After 2 hours of drying, they were crushed to fine powder and 11 ml of acidulated ultrapure water (pH ~2) was added to suppress the adsorption of Ca 2+ and other highly charged cations onto surfaces (Köhler et al . ).…”

Section: Geotectonic Setting and Main Characteristics Of Schwarzwald mentioning

confidence: 97%

Long‐term chemical evolution and modification of continental basement brines – a field study from the Schwarzwald, SW Germany

2016

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Highly saline, deep‐seated basement brines are of major importance for ore‐forming processes, but their genesis is controversial. Based on studies of fluid inclusions from hydrothermal veins of various ages, we reconstruct the temporal evolution of continental basement fluids from the Variscan Schwarzwald (Germany). During the Carboniferous (vein type i), quartz–tourmaline veins precipitated from low‐salinity (<4.5wt% NaCl + CaCl2), high‐temperature (≤390°C) H2O‐NaCl‐(CO2‐CH4) fluids with Cl/Br mass ratios = 50–146. In the Permian (vein type ii), cooling of H2O‐NaCl‐(KCl‐CaCl2) metamorphic fluids (T ≤ 310°C, 2–4.5wt% NaCl + CaCl2, Cl/Br mass ratios = 90) leads to the precipitation of quartz‐Sb‐Au veins. Around the Triassic–Jurassic boundary (vein type iii), quartz–haematite veins formed from two distinct fluids: a low‐salinity fluid (similar to (ii)) and a high‐salinity fluid (T = 100–320°C, >20wt% NaCl + CaCl2, Cl/Br mass ratios = 60–110). Both fluids types were present during vein formation but did not mix with each other (because of hydrogeological reasons). Jurassic–Cretaceous veins (vein type iv) record fluid mixing between an older bittern brine (Cl/Br mass ratios ~80) and a younger halite dissolution brine (Cl/Br mass ratios >1000) of similar salinity, resulting in a mixed H2O‐NaCl‐CaCl2 brine (50–140°C, 23–26wt% NaCl + CaCl2, Cl/Br mass ratios = 80–520). During post‐Cretaceous times (vein type v), the opening of the Upper Rhine Graben and the concomitant juxtaposition of various aquifers, which enabled mixing of high‐ and low‐salinity fluids and resulted in vein formation (multicomponent fluid H2O‐NaCl‐CaCl2‐(SO4‐HCO3), 70–190°C, 5–25wt% NaCl‐CaCl2 and Cl/Br mass ratios = 2–140). The first occurrence of highly saline brines is recorded in veins that formed shortly after deposition of halite in the Muschelkalk Ocean above the basement, suggesting an external source of the brine's salinity. Hence, today's brines in the European basement probably developed from inherited evaporitic bittern brines. These were afterwards extensively modified by fluid–rock interaction on their migration paths through the crystalline basement and later by mixing with younger meteoric fluids and halite dissolution brines.

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“…Major dyke swarms were emplaced into the Julianehåb batholith mainly in the Tuttutooq-IlimmaasaqNarsarsuaq and the Nunarsuit-Isortoq zones. They span a wide compositional range from basaltic to trachytic, phonolitic, rhyolitic, lamprophyric and carbonatitic (e.g., Upton and Emeleus 1987;Goodenough et al 2002;Halama et al 2004;Köhler et al 2009). Anorthositic xenoliths of up to 100 m size occur frequently in some of the mafic and intermediate intrusions (Bridgwater and Harry 1968).…”

Section: Geological Setting Of the Ilímaussaq Complexmentioning

confidence: 99%

“…Trace element data (e.g., enrichment of LILE, LREE, Sr and F) and isotopic signatures of other Gardar dyke rocks and volcanics suggest considerable heterogeneity. It is proposed that these magmas were generated within lithospheric mantle that was variably metasomatized because of earlier subduction processes during the Ketilidian orogeny (e.g., Upton and Emeleus 1987;Halama et al 2003;Goodenough et al 2002;Upton et al 2003;Köhler et al 2009;Upton 2013). Indeed, potential fragments of the Gardar lithospheric mantle enclosed as xenoltihs in an ultramafic lamprophyre were described by Upton (1991) from the small island of Illutalik, just a few of kilometers southwest of the Ilímaussaq complex.…”

Section: Source Constraints and Crustal Contaminationmentioning

confidence: 99%

The Ilímaussaq Alkaline Complex, South Greenland

Marks

Markl

2015

Springer Geology

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The Ilímaussaq complex in South Greenland is a well-studied multiphase alkaline to peralkaline intrusion of Mesoproterozoic age. Most of the Ilímaussaq rocks are extremely enriched in alkalis, iron, halogens, high-field-strength elements (HFSE) and other rare elements, forming one of the most differentiated peralkaline rock suites known.The major factors causing the extreme differentiation trends are low oxygen fugacity and silica activity as well as very low water activity in the melts. These inhibit the early exsolution of aqueous NaCl-bearing fluids and facilitate the enrichment of alkalis and halogens in the melts, thereby increasing the solubility of HFSE. The unusually long crystallization interval of these rocks and the suspected continuous transition from melt to fluid results in extensive (auto)metasomatism and hydrothermal overprint. Primary mineral assemblages are therefore partially resorbed in most rock units and replaced by secondary minerals to various extents.The Ilímaussaq complex is a well-known example of magmatic layering in peralkaline plutonic rocks. Recent investigations of mineral chemical trends in the layered rocks permit better understanding of their formation. The mechanism of crystal mats formation in the cooling magma causing crowding effects during settling of the layering-forming minerals is believed to govern the formation of the Ilímaussaq layered sequence.Despite more than 100 years of research and hundreds of publications on Ilí-maussaq, important aspects on the origin of some Ilímaussaq rocks, the architecture and deep structure of the complex and the significance of hydrocarbons and bitumens present in the peralkaline rocks remain unclear. Thus, plenty of room for further studies on these unusual rocks exists and interdisciplinary research is needed to better understand the genesis of this unique magmatic complex.

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Halogen and trace-element chemistry in the Gardar Province, South Greenland: Subduction-related mantle metasomatism and fluid exsolution from alkalic melts

Cited by 49 publications

References 101 publications

Origin of paleosubduction-modified mantle for Silurian gabbro in the Cathaysia Block: Geochronological and geochemical evidence

Origin of paleosubduction-modified mantle for Silurian gabbro in the Cathaysia Block: Geochronological and geochemical evidence

Long‐term chemical evolution and modification of continental basement brines – a field study from the Schwarzwald, SW Germany

The Ilímaussaq Alkaline Complex, South Greenland

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