Geochemical Evolution and Unusual Pyroxene Chemistry of the MD Tholeiite Dyke Swarm from the Archaean Craton of Southern West Greenland

Hall, R. P.; Hughes, David J.; Friend, C. R. L.

doi:10.1093/petrology/26.2.253

Cited by 23 publications

(31 citation statements)

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“…These analyses overlap with the field of clinopyroxenes in the matrices of samples MH1 and SQ2. Compositions with Ca <37 have commonly been recorded from terrestrial and lunar tholeiitic suites and are usually ascribed to the effects of cooling rate and departures from equilibrium crystallization conditions (Boyd & Smith 1971;Smith & Lindsley 1971;Arndt & Fleet 1979;Upton et al 1984;Hall et al 1985Hall et al , 1986Larsen et al 1989;Bagiński et al 2009;Mollo et al 2010). This is consistent with textural relationships in the Bracken Bay dyke, namely the progression from large euhedral phenocrysts through anhedral microphenocrysts and partially resorbed phenocrysts to matrix pyroxenes represents a trend towards faster cooling.…”

Section: Clinopyroxenesupporting

confidence: 65%

The Palaeogene Bracken Bay–Straiton dyke: composition and controls on intrusion

MacDonald

Bagiński

MacInnes

et al. 2014

SJG

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Synopsis The Bracken Bay–Straiton dyke, a member of the Palaeogene Mull dyke swarm, is one of the Solitary dykes of southern Scotland and northern England recognized by Geikie (1897). It shows a remarkable (unique?) change of strike direction, deviating from the regional NW–SE trend to propagate along the Southern Upland Fault for 16 km before apparently resuming its southeasterly course in the Southern Uplands. The dyke is a clinopyroxene–plagioclase–phyric quartz tholeiite, showing little petrographic variation along strike. However, geochemical data indicate that the dyke segment south of the Southern Upland Fault is not comagmatic with the main dyke; it is here distinguished as the Kello Water dyke. The reason for the dyke’s deviation at the fault is uncertain but may be related to a significant role for crustal heterogeneities, particularly Caledonian fractures which had earlier been utilized by the Late Carboniferous quartz dolerite dyke swarm. Supplementary material: Electron microprobe analysis data are available at http://www.geolsoc.org.uk/SUP18737 .

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Section: Clinopyroxenesupporting

confidence: 65%

The Palaeogene Bracken Bay–Straiton dyke: composition and controls on intrusion

MacDonald

Bagiński

MacInnes

et al. 2014

SJG

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“…The chemistry of the pyroxenes in the tholeiitic lavas does not differ systematically from that of pyroxenes in the transitional alkaline lavas. Localized enrichment of Ti and Al in the pyroxenes probably represents a crystallization-kinetics effect (Hall et al, 1985), rather than being a function of lava chemistry (Kushiro, 1960).…”

Section: Petrography Mineralogy and Alterationmentioning

confidence: 99%

Fractionation and contamination of Maquereau Group lavas, southern Gaspé, Québec Appalachians

Bédard¹,

Wilson²

1997

The Nature of Magmatism in the Appalachian Orogen

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Most Maquereau Group lavas are tholeiitic basalts that exhibit an Fe-Ti-enrichment trend. The tholeiites are divisible into incompatible-element-enriched and depleted types. Enriched tholeiites have chondrite-normalized La/Yb > 1 and higher incompatible element contents than do depleted, normal mid-ocean ridge basalt-like tholeiites. Subordinate transitional-alkaline basalts are even more enriched in TiO 2 , P 2 O 5 , Nb, and light rare-earth elements (REE). Intrasuite geochemical variations are consistent with coupled fractional crystallization and assimilation of Grenvillean continental crust or sediments derived therefrom. Assimilation leads to the development of characteristic enrichment in Ba, Th, Zr, and light REE. Intersuite variations cannot be accounted for through crystal fractionation or crustal contamination, and must reflect either source-mantle heterogeneity or mantle melting processes. Most major-and trace-element paleotectonic discriminants do not favor an arc-related environment for these lavas. An intracontinental rift or an incipient spreading ridge environment are most consistent with the geochemical data and field relationships.

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“…Multiple linear regressions were performed against increasingly elaborate combinations of mineral compositional variables; melt compositional variables; melt and mineral compositional variables; and added temperature and pressure constraints (Table S2). Variations of Dtraces versus DCaO as advocated by Jones [] were not considered because of the known mobility of CaO in altered terrestrial basalts and the potential for kinetically induced variations of cpx Ca contents [ Hall et al ., ]. Major element D values are included in the database, however, allowing such an approach to be explored if desired.…”

Section: Introductionmentioning

confidence: 99%

Parameterizations of calcic clinopyroxene—Melt trace element partition coefficients

Bédard

2014

Geochem Geophys Geosyst

125

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Cpx/liquid D for the rare earth elements were fit to the lattice strain model to derive fits that can reproduce the cpx/ liquid D REE profile shapes (REE 5 rare earth elements). These fits indicate that cpx/liquid D REE for melts more evolved than picritic basalts cannot be modeled assuming that all REE are in octahedral coordination in a single M2 site, but also require sixfold partitioning into an M1 site for Lu-Yb-Tm-Er.

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Geochemical Evolution and Unusual Pyroxene Chemistry of the MD Tholeiite Dyke Swarm from the Archaean Craton of Southern West Greenland

Cited by 23 publications

References 0 publications

The Palaeogene Bracken Bay–Straiton dyke: composition and controls on intrusion

The Palaeogene Bracken Bay–Straiton dyke: composition and controls on intrusion

Fractionation and contamination of Maquereau Group lavas, southern Gaspé, Québec Appalachians

Parameterizations of calcic clinopyroxene—Melt trace element partition coefficients

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