摘要:

The Proterozoic iron ores of the Kiruna district, northern Sweden, occur as discontinous lenses of magnetite and hematite up to 4 kilometers in length within a sequence of felsic porphyries. The association of low-grade felsic volcanics and sedimentary rocks with basaltic pillow lavas and granitic rocks shows a strong similarity to typical Archean greenstone belts. Primary younging indicators, bedding/cleavage relationships, and minor fold symmetries through the district suggest that the area occupies the eastern limb of a major antiform, cored by granitic rocks to the west. A steep regional cleavage, inhomogeneously developed through the district, suggests one major episode of compressional deformation. The cleavage and associated flattened clasts indicate a compression direction plunging 10°WNW. Elongate clasts, boudins, and fibrous veins indicate a strong extension plunging 60°SSE, parallel to fold hinge lines. Boudinage of the major ore bodies to produce their present distribution is compatible with the estimated strain of a single deformation. Diapirism is suggested as a likely explanation of the observed strain patterns.

ISSN:0016-786X    

DOI:10.1080/11035898409454620

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Data are presented from the Taavinunnanen gabbro massif in Lappland, Sweden. Olivine, augite, bronzite and plagioclase have been analysed. Samples have been taken from outcrops as well as from a 700 metres long core drilled vertically through the gabbro. It is concluded that the gabbro body is a composite, differentiated layered intrusion of lopolithic shape exhibiting cryptic as well as rhythmic layering. The original magma is suggested to be of tholeiitic composition.

ISSN:0016-786X    

DOI:10.1080/11035898409454621

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

δ18O and δ13C for limestones, calcite fissure infillings and calcite precipitated on the present rock surface have been analysed. The calcite samples were collected from different geological environments in Sweden. Most results can be correlated to crystallization conditions or redistribution due to fluid activation in fissures.

ISSN:0016-786X    

DOI:10.1080/11035898409454622

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The early Proterozoic supracrustal sequence in the Garpenberg district, south central Sweden, consists mainly of quartz-feldspar gneissses (‘leptites’) and subordinate amphibolites, quartz gneisses, mica schists, skarns and marbles. Stratabound iron and sulfide deposits are intercalated within this sequence. Most of the quartz-feldspar gneisses and amphibolites are interpreted as acid and basic metavolcanic rocks. The quartz gneisses and mica schists represent the metamorphic equivalents of originally altered felsic volcanic and sedimentary rocks. The geologic development of the Garpenberg district was dominated by extensive acid volcanism of calc-alkaline affinity, which was interrupted by periods of intense hydrothermal activity, ore deposition and sedimentation. Most of the volcanic activity occurred was submarine in a shallow-water environment. Subsequently, the supra crustal sequence was affected by the Svecokarelian orogeny (1800–1750 Ma) and the rocks were metamorphosed in the amphibolite facies, folded and intruded by synorogenic granitoids.

ISSN:0016-786X    

DOI:10.1080/11035898409454623

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035898409454624

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The Hällefors sulfide ores are located in the westernmost part of Bergslagen Ore Province, south central Sweden. The ore-bearing rock sequence consists of K-rich felsic metavolcanics. In the eastern part of the field, stratiform ore occurs in the upper part of a 30–40 m thick limestone. This ore consists of carbonate-bearing manganiferous skarn rock with conformable sulfide- and/or magnetite-rich beds. In the ore there are interlaycred beds of limestone, dolomite and tuffite. The sulfide skarn ironoxide ore is interpreted as a product of regional metamorphism of pre-existing strata. It comprises four chemical components, which are suggested to represent tuff materials (Si, Al, K), and chemically precipitated oxides (Fe, Mn), carbonates (Ca, Mg) and sulfides (S, Zn, Pb, As, Ag). The precipitates are considered to be products of submarine hydrothermal activity. The absence of wallrock alteration and channelways for ore-bearing solutions indicates that the ore was deposited on the sea floor distally to the outlet vents of the solutions. The ore and the wallrock are intensely faulted; the sulfides, especially galena, have been partly remobilized into faults and fissures. The Zn-Pb vein mineralizations in the western and middle parts of the field may be remobilization products of older stratiform ores.

ISSN:0016-786X    

DOI:10.1080/11035898409454625

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Thirteen samples of the primorogenic Haparanda suite in Norrbotten, northern Sweden, are analysed for major elements and the trace elements Rb, Sr, Ba, Cu, Zn, Mo, Sn, Be, Nb, Y, Zr, Cr, Ni, V, F, Cl and S. The results accord with the view that the Haparanda suite is an I-type rock suite generated in a compressional environment. The Sn-content is higher than expected but Sn, Mo and Be are not enriched in the most silicic samples. The F-content is highest in gabbros and Mo is correlated with Cu.

ISSN:0016-786X    

DOI:10.1080/11035898409454626

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035898409454627

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Rb-Sr whole rock analysis of postorogenic Svecokarelian granites west of Ludvika, central Sweden, mapped as Järna granite, gives two isochrons of 1675 ± 12 Ma and 1734 ± 14 Ma, respectively.

ISSN:0016-786X    

DOI:10.1080/11035898409454628

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Sverigeite, NaMgMnBe2SnSi3O12(OH), is orthorhombic, space groupIbmmorIbm2 with a = 6.818(6), b = 13.273(8), and c = 10.815(8) Å. The strongest reflections in the X-ray powder diffraction pattern are: 2.884(202); 2.826(042); 4.35(121); 5.77(101); 2.644(222); and 6.63 Å (020). Chemical analyses yielded SiO233.5, FeO 0.3, ZnO 1.2, MgO 8.1, MnO 11.8, Na2O 6.1, BeO 9.7, SnO228.5, H2O 1.2, sum = 100.4 weight percent, in good agreement with the proposed formula with Z = 4. Sverigeite is yellow in color; the hardness (Mohs) is approximately 6 1/2; the density is 3.60 (meas.), 3.61 (calc)g/cm3; cleavage is perfect on {010}. Optically, sverigeite is biaxial positive, 2V = 67°, with indices of refraction α = 1.678(4), β = 1.684(4) and γ = 1.699(4); dispersion is strong r > v; pleochroism is moderate: X = yellow, Y ≃ Z = pale yellow; absorption X > Y ≃ Z; orientation: Z = b. Sverigeite is found associated with mimetite, jacobsite, manganoan calcite, and amphibole. The only known sample was found on the dumps of the Långban Mine, Värmland, Sweden. This new species is named for Sweden, the country of origin.

ISSN:0016-786X    

DOI:10.1080/11035898409454629

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor