207Pb/206Pb whole-rock age of gneisses from the Kangerdlugssuaq area, eastern Greenland

Leeman, William P.; Dasch, E. Julius; Kays, M. A.

doi:10.1038/263469a0

Cited by 39 publications

(12 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cohen & O'Nions (1982) and that of Iceland from Sun & Jahn (1975) and Sun et al (1975). The growth curve is from Stacey & Kramers (1975) and the basement isochron from Leeman & Dasch (1976). Based on Nd/Sr isotope systematics it is not possible to make any distinction between these formations and locations.…”

Section: The Plateau Basaltsmentioning

confidence: 99%

“…mainly of high amphibolite facies gneisses with scattered inclusions of granulite facies rock types (Leeman & Dasch 1976;Bird et al 1986). isotopic and elemental compositions of outcropping basement and basement xenoliths in basaltic dykes from the Kangerdlugssuaq area have been analysed (Holm, unpublished data;Hamilton 1970;Leeman & Dasch 1976). Owing to the great age of the crustal rocks the analysed crustal rocks display a very large range of isotopic values, but they do not overlap with the range of the basaltic rocks.…”

Section: Inferences From the Geochemistry Of The Two Lava Groupsmentioning

confidence: 99%

See 1 more Smart Citation

Nd, Sr and Pb isotope geochemistry of the Lower Lavas, E Greenland Tertiary Igneous Province

Holm

1988

View full text Add to dashboard Cite

Summary New Sr, Nd and Pb isotopic and trace-element data are presented for the Lower Lavas and some Plateau Basalts. Ranges of isotopic compositions are large among the lower and middle Vandfaldsdalen Formation lavas ( 87 Sr/ 86 Sr=0.7033–0.7073; 143 Nd/ 144 Nd=0.5124–0.5130; 206 Pb/ 204 Pb=15.1–17.5; 207 Pb/ 204 Pb=14.7–15.6; 208 Pb/ 204 Pb=35.0–39.1) and show a decrease in range of values with stratigraphic height. The youngest flows among the Lower Lavas have compositions similar to the Plateau Basalts of the late Skrænterne and Igtertiva Formations as well as of Nansen Fjord and Wiedemann Fjord, all of which are near to Icelandic composition ( 87 Sr/ 86 Sr=0.7031–0.7036; 143 Nd/ 144 Nd=0.5129–0.5131; 206 Pb/ 204 Pb=17.1–18.4; 207 Pb/ 204 Pb=15.3–15.4; 208 Pb/ 204 Pb=37.6–38.0). The lavas constitute two groups, one of which (group 2) is restricted to the lower parts of the succession. The source for this group can be modelled by mixing between an enriched old lithospheric mantle and an ocean island basalt (OIB)-type mantle with a relatively small component of depleted asthenosphere. The other group (group 1) is the most common and can be modelled by mixing between a typical Icelandic source component and a second, less enriched, lithospheric mantle component. Contamination from continental crust was of minor overall importance. The geochemical evolution in basic E Greenland Tertiary lavas is believed to reflect the interaction between the asthenospheric mantle, 3 Ga old continental lithospheric mantle and the mantle jet which is presently positioned under Iceland. With time the most enriched lithospheric source quickly decayed while the less enriched lithospheric source was important during most of Vandfaldsdalen Formation times. The OIB-type source prevailed throughout lava eruption with the asthenospheric contribution larger in the Miki Formation and the Plateau Basalts.

show abstract

Section: The Plateau Basaltsmentioning

confidence: 99%

Section: Inferences From the Geochemistry Of The Two Lava Groupsmentioning

confidence: 99%

Nd, Sr and Pb isotope geochemistry of the Lower Lavas, E Greenland Tertiary Igneous Province

Holm

1988

View full text Add to dashboard Cite

show abstract

“…2980, 2860, 2835, 2755, and 2735 Ma, pegmatites yield ages of ca. 2630 Ma interpreted as the age of amphibolite facies retrogression in the south (Leeman et al, 1976;Kays et al, 1989;Kalsbeek et al, 1993;Nutman et al, 2008b). However, amphibolite facies metamorphism at 650-700°C and 3-4 kbar in the Kangerlussuaq Fjord area was dated at ca.…”

Section: Accepted Manuscriptmentioning

confidence: 94%

Metallogeny of Greenland

Kolb

Keiding

Steenfelt

et al. 2016

Ore Geology Reviews

View full text Add to dashboard Cite

“…Rifting began in the Late Cretaceous with the formation of faultcontrolled basins in Precambrian gneiss and amphibolite (Leeman, Dasch & Kays, 1976;Kays, Goles & Grover, 1989), and between 62 and about 50 Ma, flood basalts several kilometres thick filled a subsiding rift basin floored by Cretaceous to Upper Palaeocene sediments (Soper et al 1976;Sinton et al 1994). Penecontemporaneous plutonic activity produced numerous layered gabbro intrusions along the unconformity between the sedimentary rocks and basalts and the underlying gneisses.…”

Section: Geology Of the Gabbro Complex 2a Regional Settingmentioning

confidence: 96%

Petrology and geochemistry of the Kruuse Fjord Gabbro Complex, East Greenland

Arnason

Bird

Bernstein³

et al. 1997

Geol. Mag.

View full text Add to dashboard Cite

The Kruuse Fjord Gabbro Complex is a composite intrusion of layered gabbro and troctolite with subordinate ultramafic rocks and minor trondhjemitic bodies. It was emplaced into Archaean continental crust of East Greenland during early Tertiary rifting of Greenland from Eurasia. The work to date has identified an outer gabbro series and an inner troctolite series, and these are separated by a narrow zone of trondhjemitic intrusions. In the southeast, the partially crystallized cumulates of the gabbro series were intruded by a lenticular, ultramafic pluton 800 m in thickness. Volumetrically minor, syenite–trachyandesite net-veined dykes and later, diabase dykes cross-cut the plutonic rocks. Structural and topographic features suggest that the layered rocks were affected by synmagmatic subsidence and deformation but not by monoclinal coastal flexure.The gabbro series is composed of a marginal gabbro unit, about 20 m wide, bordering more than a 2 km thickness of layered olivine and magnetite gabbro cumulates. The marginal gabbro is interpreted to be chilled magma. The layered cumulates are the product of repeated injections of magma that fractionated in an open-system magma chamber. Anorthositic and troctolitic layers in the lower part of the sequence may represent inputs of magma and suggest that the order of cumulus mineral crystallization was (1) plagioclase (An39–85), (2) olivine (Fo46–82), (3) augite (Wo28–47En39–58Fs8–18 ) and (4) magnetite. The disappearance of cumulus magnetite and a reversal in mineral compositions at 1.5 km from the base of the succession suggests a major input of magma occurred at this height. In the troctolite series, the composition of cumulus minerals, mineral crystallization sequence and style of emplacement are similar to those in the gabbro series. The ultramafic pluton is composed of coarse-grained wehrlite, olivine melagabbro and troctolite that were formed by at least three injections of magma. The typical mineral crystallization sequence was (1) cumulus chromite and olivine (Fo84–88); (2) poikilitic chrome diopside (Wo29–51En43–63Fs3–13 ); and (3) intercumulus plagioclase (An75–90), phlogopite, apatite and localized disseminated sulphides containing Au and platinum-group elements.Comparison of crystallization sequences and the major and trace element compositions of clinopyroxene suggests that the gabbroic and troctolitic rocks formed from a magma represented by the chilled marginal gabbro, a tholeiitic basalt magma similar to E-MORB, whereas the ultramafic rocks formed from a magma that was relatively enriched in incompatible trace elements and volatiles. The association of these two magma types is an example of bimodal mafic–ultramafic magmatism in a rifting environment.

show abstract

207Pb/206Pb whole-rock age of gneisses from the Kangerdlugssuaq area, eastern Greenland

Cited by 39 publications

References 13 publications

Nd, Sr and Pb isotope geochemistry of the Lower Lavas, E Greenland Tertiary Igneous Province

Nd, Sr and Pb isotope geochemistry of the Lower Lavas, E Greenland Tertiary Igneous Province

Metallogeny of Greenland

Petrology and geochemistry of the Kruuse Fjord Gabbro Complex, East Greenland

Contact Info

Product

Resources

About