Polyorogenic Nature of the Southern Caledonian Fold Belt in East Greenland: An Isotopic Age Study

Steiger, R.; Hansen, Bent; Schuler, Ch.; Bar, M.; Henriksen, N

doi:10.1086/628441

Cited by 68 publications

(37 citation statements)

References 12 publications

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“…--"Em y 2 5 : (Rex et al 1977;Hansen et al 1978;Steiger et al 1979). Although the recognition of Grenvillian metamorphism in the Krummedal sequence is accepted by many authors (Higgins et al 1981), it is proposed here that the inner Forsblads Fjord rocks are not equivalent to the Krummedal supracrustals, but rather correlate with the lower parts of the Eleonore Bay Group, which show high-grade Caledonian metamorphism (Caby 1980;Caby et al 1981).…”

Section: Geological Settingmentioning

confidence: 99%

“…Caledonian metamorphism has affected all the formations of the East Greenland fold belt: witness the majority of mineral ages (372-510 Ma total range in Higgins and Phillips 1979). The main phase of Caledonian metamorphism is dated by granite emplacement ages at between 475 and 400 Ma ago (Steiger et al 1979). This period also corresponds to the formation of migmatites in the eastern part of Gaoasefjord, in the Stauning Alps, and Renland (Chadwick 1975).…”

Section: Late Proterozoic Metasedimentary Successions: Eleonore Baymentioning

confidence: 99%

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Resistance of zircons to U–Pb resetting in a prograde metamorphic sequence of Caledonian age in East Greenland

Peucat¹,

Tisserant²,

Caby³

et al. 1985

Can. J. Earth Sci.

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In the Alpefjord area, Caledonian metamorphism from the chlorite zone to the sillimanite zone is seen to cut across the sedimentary pile of the lower Eleonore Bay Group. Zircons have been collected from quartzite layers enriched in heavy minerals.U-Pb zircon dating in the chlorite and the sillimanite zones does not reveal the Caledonian event but, instead, previous episodcs at I I00 and 1500 Ma ago. The Caledonian event can be recognized in anatectic gneisses where detrital zircons are sunoundcd hy overpowths, K-Ar and Rb-Sr methods yicld 1030-410 Ma ages on micas, with a positive correlation between thc degree of apparent resetting of mica ages and the grade of the Caledonian metamorphism.The following geological interpretation of the age data is proposed. (1) A major metamorphic event occurred around 1100 Ma ago in the source area for the lower Eleonore Bay Group sediments. During this Grenvillian event, Archaean detrital zircons werc affected by an episodic lead loss and a muscovite phase recorded the cooling and uplift of a basement source area. (2) Emsion of this snurcc area occurred after I I00 Ma. followcd by sedimentation of the lower Eleonore Bay Group (~7 0 0 Ma ago). The 2500-1100 Ma U-Pb system remained nearly a closed system during Caledonian metamorphism up to and including sillimanitc-zone conditions. This example shows the peat resistance of inherited zircons to an important secondary Pb loss during Caledonian metamorphism and consequently shows that the lower-intercept ages of zircons from metasedimentary rocks do not always record the fast metamorphic event observed in situ. hut retain mcmnries of previous geological events in the sedimentary source areas. By contrast. zircons separated from quartzitic xenoliths in migmatitic gneisses have recorded a disturbance in their U-Pb systems ~hnt corresponds to Caledonian partial melting.On observe dans la rCgion d'Alpefjord que le mCtamorphisme prograde de la chlorite 9 la sillimanite traverse I'empilement ~Cdimentaire du groupe Eleonore Bay infkrieur. Des zircons furent recueillis dans les couches de quartzite enrichies en minCraux lourds.La datation U-Pb du zircon dans les zones 3 chlorite et a sillimanite n'indique pas d'CvCnement calCdonien mais rCvkle des Cpisodes anttrieurs situes a 1 100 et 2500 Ma. L'CvCnement caledonien peut 2tre reconnu par les excroissances qui entourent les zircons dCtritiques dans les gneiss anatectiques. Les mCthodes K-Ar et Rb-Sr appliqutes sur les micas fournissent des Lges de 1030 a 410 Ma et indiquent une corrtlation positive entre le stade de rajeunissement apparent et I'intensitt du mCtamorphisme calCdonien.Voici ce que nous proposons comme interprktation gkologique des mesures de datation. (I) un evenernent rnetamorphique important se manifesta il y a environ 1100 Ma dans la rtgion nourriciere des skdiments du groupe Eleonore Bay infkrieur. Durant cet tvtnement grenvillien, les zircons dCtritiques archtens ont subi des pertes de plomb Cpisodiques et une phase de muscovite ttmoigne d'un episode de refroidissement et...

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Section: Geological Settingmentioning

confidence: 99%

Section: Late Proterozoic Metasedimentary Successions: Eleonore Baymentioning

confidence: 99%

Resistance of zircons to U–Pb resetting in a prograde metamorphic sequence of Caledonian age in East Greenland

Peucat¹,

Tisserant²,

Caby³

et al. 1985

Can. J. Earth Sci.

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“…The chronology of emplacement through radiometric dating is not yet well known, although several Rb-Sr studies, notably those of Hansen & Tembusch (1979), Steiger et al (1979) and Rex & Gledhill (1981), supported by the U-Pb studies of Steiger et al (1979) are particularly important in this respect. The pioneering K-Ar work of Hailer & Kulp (1962) must now be regarded with caution in view of its tendency to give young ages reflecting cooling rather than emplacement.…”

Section: E Greenlandmentioning

confidence: 99%

Granitoid plutonism in the Caledonian orogen of Europe

Stephens¹

1988

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Granitoid plutonism is a feature of all major segments of the Caledonian orogen in NW Europe and Greenland. Available data on geological setting, age and composition are presented for each segment and are collated for use as the basis for a regional and temporal interpretation of magmatism during the Caledonian. Magmatism close to the northwestern foreland was dominantly alkaline whereas both alkaline and peraluminous compositions are represented on the southern foreland. Within the orogen early magmatism N of the Iapetus suture line was dominantly S-type resulting from crustal anatexis of dominantly metasedimentary rocks, while there is a later shift to predominantly I-type granitoid plutonism. S of the Iapetus suture line plutonism within the orogen in Scandinavia is essentially I-type, whereas in Britain and Ireland it has more S-type characteristics supporting recent propositions of two separate southerly plates. The overall pattern of plutonism contrasts markedly with that of younger subduction-related batholiths.Granitoid plutonism was a feature of all major segments of the orogen in Europe from early Ordovician to Devonian. A wide variety of compositional types was generated in response to prevailing tectonic and metamorphic conditions as well as varying source regions and further modification by igneous processes. The object of this paper is to collate data on geological setting, geochronology and composition of the granitoids in terms of their spatial and temporal distributions and to use these data to relate Caledonian plutonism to the dynamic development of the orogen in Europe. It is convenient first to consider plutonism within a framework of present segments of the Caledonian orogen (Fig. 1), and for this purpose the E Greenland and N African segments have been included with European segments. The availability of detailed information on plutonism in the various segments is highly variable, being rather sparse in remote areas such as Svalbard and E Greenland. Perhaps the greatest uncertainties concern the emplacement ages of plutons because radiometric techniques date time elapsed since passing through a blocking temperature. This becomes a problem in slow-cooling terranes or in plutons which have been subsequently metamorphosed above the blocking temperature. Available radiometric ages have been viewed critically, but detailed revision of the scheme presented here will be necessary as better geochronological data becomes available.The geological setting of plutonism is considered on a regional scale in a generalized way by relating plutons to their environment, i.e. whether they were emplaced into old (Archaean or early mid-Proterozoic) crystalline basement or young (late Proterozoic-early Palaeozoic) geosynclinal sequences. A consistent ornamentation for each uJ

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“…The granites form large massive bodies as well as minor dikes and are confined to the border zone between the Central Metamorphic Complex and the Eiconore Bay Group sediments. The granites vary in composition and age (Steiger et al, 1979;Rex and Gledhill, 1981). Granodiorite, monzonite, and two-mica granite show ages from 550 to 475 m.y.…”

Section: The Discovery Of Mineralization In the East Greenland Caledomentioning

confidence: 99%

Strata-bound copper sulfide and nonstrata-bound arsenopyrite and base metal mineralization in the Caledonides of East Greenland; a review

Stendal¹,

Ghisler

1984

Economic Geology

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In the central East Greenland Caledonides there are numerous occurrences of stratabound copper mineralization and hydrothermal arsenic and tungsten mineralization. The host rocks are metasediments of middle Proterozoic and unmetamorphosed to slightly metamorphosed late Proterozoic sediments (quartzite, shale, limestone), all intruded by Caledonian granites.Strata-bound copper mineralization 0.2 to 2 m thick is found at different stratigraphic levels in late Proterozoic shale and quartzite and extends over a distance of 275 km. The mineral assemblages in the shale are dominated by chalcopyrite-pyrite, bornite-chalcocite, or chalcocite. The sulfide associations in the quartzite are chalcopyrite-pyrite-(pyrrhotite) or chalcopyrite-pyrite-(tetrahedrite). In addition strata-bound sulfide-bearing veins occur. The grade of the mineralized zones varies from 0.05 to 1.35 percent Cu. The strata-bound copper sulfides were probably concentrated mainly by diagenetic processes but later were modified by metamorphic mobilization and locally enriched by hydrothermal solutions.Hydrothermal scheelite and arsenopyrite mineralization is located mainly close to the border zone between the Central Metamorphic Complex and the late Proterozoic sediments.Three main types of scheelite mineralization occur: (1) a skarn type, (2) a vein type, and (3) a breccia type. The skarn type is hosted by marble, schist, and calc-silicate rocks. The tungsten content varies from 0.1 to 1 percent W with enrichment of the elements Be, Bi, F, Li, and Sn. Scheelite mineralization in quartz veins yields 0.1 percent W associated with enhanced contents of As, Be, Bi, F, Li, Pb, and Sn. The skarn and vein types are closely related to Caledonian granitic intrusions. The scheelite (_stibnite) mineralized breccia type is found in fault zones probably connected with a granite. These occurrences contain 0.8 to 3 percent W and up to 2.4 Sb and represent at the moment the only mineral deposit of potential economic interest in the area.The arsenopyrite mineralization is regionally widespread. Mineralized quartz veins occur in both quartzitic and semipelitic sediments, whereas mineralized fracture zones are restricted to semipelitic quartzite. The arsenopyrite mineralization is often associated with scheelite, galena, pyrrhotite, chalcopyrite, sphalerite, and traces of gold and silver.The distribution of the elements in the scheelite and arsenopyrite mineralization indicates a zonation around the Caledonian granites. In general, elements such as Be, Bi, F, Li, and Sn are concentrated within 1 to 2 km from the contact. At a greater distance, up to 7 km, the metals Bi, Co, Cu, Pb, and Zn are typical. In terms of fluid inclusions in the veins, the homogenization temperatures of boiling CO2-bearing water of moderate salinity are from 225 ø to 260øC with a pressure of approximately 1 kb.

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Polyorogenic Nature of the Southern Caledonian Fold Belt in East Greenland: An Isotopic Age Study

Cited by 68 publications

References 12 publications

Resistance of zircons to U–Pb resetting in a prograde metamorphic sequence of Caledonian age in East Greenland

Resistance of zircons to U–Pb resetting in a prograde metamorphic sequence of Caledonian age in East Greenland

Granitoid plutonism in the Caledonian orogen of Europe

Strata-bound copper sulfide and nonstrata-bound arsenopyrite and base metal mineralization in the Caledonides of East Greenland; a review

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