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

Abstract

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.

Lead isotope studies on mineral showings and ore deposits in East Greenland

“…Thc oil)' Illaterial appears LO h,IVC migralcd along (he fault zone from buricd oil-gcncrating rm. :h or oil accumulalions (Christiansen et lIl.. 1991 (Stendal & Ghisler, 1984). The samc mincralised beds ean outcrop as rnuch as 275 km apart (Fig.…”

Mineral occurrences in central East and North-East Greenland—new possibilities?

“…12 Neoproterozoic strata-bound copper mineralization is known from the Eleonore Bay Supergroup. 8,9,50,51 Mineral occurrences related to Caledonian lineaments Arsenic is found in several places and is particularly concentrated in the Alpefjord 47,48 and Andrée Land 54 regions as arsenopyrite. The arsenopyrite was formed hydrothermally and is distributed in fracture and vein systems closely related to the contact between the Eleonore Bay Supergroup and the older metamorphic crystalline complex.…”

The mineral occurrences of central East Greenland

“…Nielsen (1973), in his summary of mineral occurrences in Greenland, included selected examples from central East Greenland, and the same data are presented in the monographs "Geology of Greenland" (Nielsen 1976) and "Mineral Deposits of Europe" (S0rensen et al 1978). A more comprehensive review, which however only incorporates the mineralization hosted in parts of the pre-Caledonian sediments, has recently been published (Stendal & Ghisler 1984). Internally, Nordmine has prepared an inventory of the mineral potential twice (Hintsteiner 1972 andGeyti et al 1979) .…”

“…These finds led to continued investigations throughout the EBG basin located between 72°N and 74°N. In the mid-seventies parallel investigations were carried out by a group from the University of Copenhagen (Stendal 1979aand b, 1980b, Ghisler et al 1980aand b, Stendal & Hock 1981, Stendal 1982a, Stendal & Ghisler 1984 and by Nordmine (Appel 1974, Moeri 1975, Gruner & Probst 1976. Nordmine later investigated occurrences on Ymer 0 (Hallenstein 1982) and on Canning Land (Harp0th 1982).…”

“…Later investigations by the University of Copenhagen (Stendal 1979b, Ghisler et al 1980a) and by Nordmine (Thum et al 1971, Stendal 1980aand c, Lind 1980, Pedersen 1980b have revealed extensive scheelite and arsenopyrite mineralization. The results are summarized by Stendal ( 1982b), Pedersen (1982 and and Stendal & Ghisler (1984).…”