| 1. |
|
|
| 2. |
|
|
| 3. |
- Holtstam, Dan, 1963-
(författare)
-
Den outsläckliga törsten efter kobolt
- 2019
-
Ingår i: Geologiskt forum. - Stockholm. - 1104-4721. ; 2019:103, s. 25-28
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The shift to electric vehicles and the growing production of rechargeable batteries needed in these have dramatically increased the global demand for cobalt. Most of the metal comes from less stable areas in the world, which makes the supply precarious. The article describes the present situation (in Swedish), and gives a brief overview of the main sources of cobalt in the world today and the prospects for exploiting reserves in Sweden.
|
|
| 4. |
- Holtstam, Dan, et al.
(författare)
-
Origin of REE mineralization in the Bastnas-type Fe-REE-(Cu-Mo-Bi-Au) deposits, Bergslagen, Sweden
- 2014
-
Ingår i: Mineralium Deposita. - : Springer Science and Business Media LLC. - 0026-4598 .- 1432-1866. ; 49:8, s. 933-966
-
Tidskriftsartikel (refereegranskat)abstract
- The Bastnas-type deposits, with mineral assemblages of Fe oxides, Ca-Mg silicates, rare earth element (REE) silicates, REE fluorocarbonates, and Cu-Fe-Mo-Bi sulfides, are associated with marble horizons in a strongly Na, K, and/or Mg altered, metavolcanic succession, over a distance of at least 80 km in a SW-NE trending zone in western Bergslagen. Two subtypes occur: (1) enriched (relative to the other type) in light REE (LREE) and Fe, exemplified by the Bastnas and Rodbergsgruvan deposits, and (2) enriched in heavy REE (HREE), Y, Mg, Ca, and F, represented by deposits in the Norberg district. Bastnasite hosts primary fluid H2O-CO2 inclusions with salinities of 6-29 eq. wt% CaCl2 and with total homogenization temperatures (Th-tot) of ca. 300-400 degrees C. Subtype 2 has late-stage fluorite with fluid inclusions that show 1-16 eq. wt% NaCl and Th-tot of ca. 90-150 degrees C. Molybdenite Re-Os ages obtained from three deposits are 1,904 +/- 6, 1,863 +/- 4, and 1,842 +/- 4 Ma. Nd isotopic data from five different REE minerals yielded no defined isochron, but a range in epsilon(Nd) (1.88 Ga) of +0.2 to +1.6. The oxygen isotope values (delta O-18(SMOW)) of dolomite and calcite from the associated REE-mineralized skarn and recrystallized carbonate assemblages lie in the range 6.1-8.6 parts per thousand, overlapping with those of the host marbles. Carbon isotope values (delta C-13(PDB)) show typical magmatic signatures of -6.7 to -4.4 parts per thousand, while the host marbles group around ca. -2.4 parts per thousand. The sulfur isotope (delta S-34(CDT)) values of associated sulfides range between -10.8 and +0.2 parts per thousand. The combined evidence suggests REE mineralization, beginning at 1.9 Ga, from mainly Svecofennian, juvenile magmatic (>400 degrees C) fluids carrying Si, F, Cl, S, CO2, and the REE in addition to other metals; mineralization occurred through reactions with dolomitic layers in the supracrustal units coevally with regional metasomatic alteration associated with fluid circulation through an extensive active volcano-plutonic complex.
|
|
| 5. |
|
|
| 6. |
- Holtstam, Dan, et al.
(författare)
-
Ulfanderssonite-(Ce), a new Cl-bearing REE silicate mineral species from the Malmkärra mine, Norberg, Sweden
- 2017
-
Ingår i: European journal of mineralogy. - : Schweizerbart. - 0935-1221 .- 1617-4011. ; 29:6, s. 1015-1026
-
Tidskriftsartikel (refereegranskat)abstract
- Ulfanderssonite-(Ce) is a new mineral (IMA 2016-107) from the long-abandoned Malmkärra iron mine, one of the Bastnäs-type Fe-rare earth element (REE) deposits in the Bergslagen ore region, central Sweden. It is named for Ulf B. Andersson, a Swedish geologist and petrologist. In the type specimen, the mineral occurs with västmanlandite-(Ce), bastnäsite-(Ce), phlogopite, talc, magnetite, pyrite, fluorbritholite-(Ce) and scheelite. Ulfanderssonite-(Ce) forms pinkish, translucent subhedral grains, 100-300 mu m, in aggregates up to 2 mm. Fracture is uneven, and there is an indistinct cleavage parallel (001). Mohs' hardness is 5-6, D-calc = 4.97 g cm(-3). Optically, ulfanderssonite-(Ce) is nonpleochroic, biaxial negative, with 2V(meas) = 55 degrees and n(calc) = 1.82. The ideal composition is Ce15CaMg2(SiO4)(10)(SiO3OH)(OH,F)(5)Cl-3. Electron microprobe and LA-ICP-MS chemical analyses yielded (in wt%) La2O3 11.87, Ce2O3 30.98, Pr2O3 3.99, Nd2O3 17.14, Sm2O3 2.81, Eu2O3 0.18, Gd2O3 1.15, Dy2O3 0.30, Tb2O3 0.10, Y2O3 1.11, CaO 2.26, FeO 0.02, MgO 1.97, P2O5 0.08, SiO2 19.13, H2Ocalc 1.07, F 1.09, Cl 2.89, O=(F, Cl) -1.10, sum 97.04. The five strongest powder X-ray diffraction lines are [I(%) d(obs) (angstrom) (hkl)]: 100 2.948 (- 421), 47 2.923 (204), 32 2.660 (- 225), 26 3.524 (40-1), 25 1.7601 (6-23). Ulfanderssonite-(Ce) is monoclinic, Cm, with a = 14.1403(8), b = 10.7430(7), c = 15.498(1) angstrom, b = 106.615(6)degrees and V = 2256.0 (2) angstrom 3 for Z = 2. The crystal structure has been solved by direct methods and refined to R-1 = 2.97% for 5280 observed reflections. It consists of a regular alternation of two layers, designated A and B, along the c-axis: A (ca. 9 angstrom thickness), with composition [(Ce8Ca) MgSi7O22(OH, F) 4](8+), and B (ca. 6.5 angstrom), with composition [Ce7MgSi4O21(OH, F)(2)Cl-3](8); the A layer is topologically and chemically closely related to cerite-(Ce). A FTIR spectrum shows strong absorption in the region 2850-3650 cm(-1), related to the presence of OH stretching bands. Ulfanderssonite-(Ce) is interpreted as a primary mineral at the deposit, along with the more common fluorbritholite-(Ce), formed by a magmatic-hydrothermal fluid with REE, Si, F and Cl ion complexes reacting with dolomite marble. The presence of ulfanderssonite-(Ce) is direct evidence of a Cl-rich mineral-forming aqueous solution, normally not reflected in the composition of skarn minerals in Bastnäs-type deposits.
|
|
| 7. |
- Jansson, Nils F., et al.
(författare)
-
Age constraints on c. 1.9 Ga volcanism, basin evolution and mineralization at the world-class Zinkgruvan Zn-Pb-Ag(-Cu) deposit, Bergslagen, Sweden
- 2023
-
Ingår i: Precambrian Research. - : Elsevier. - 0301-9268 .- 1872-7433. ; 395
-
Tidskriftsartikel (refereegranskat)abstract
- We present improved age constraints for the world-class Zinkgruvan Zn-Pb-Ag and Cu deposit: one of the largest Zn deposits of the Fennoscandian shield, and one of the earliest large, basin-hosted Zn deposits that formed from oxidized saline brines. Secondary Ion Mass Spectrometry (SIMS) U-Pb dating on zircon is used to constrain at least two phases of c. 1.9 Ga volcanism in the Zinkgruvan area, separated by a period of fluvial sedimentation, all of which predated formation of the stratiform Zn-Pb-Ag mineralization. A 1908 ± 4 Ma age for a rhyolitic rock of the first volcanic phase is the oldest recorded U-Pb zircon age of a volcanic rock in the Bergslagen lithotectonic unit (BLU) where Zinkgruvan is located. Similarly, two identical ages of 1898 ± 5 Ma for volcanic rocks belonging to the second volcanic phase indicate that the local volcanic activity, which formed the stratigraphic footwall, ended earlier in the Zinkgruvan area than in other parts of the BLU, where intense explosive felsic volcanic and intrusive activity until c. 1891 Ma has been demonstrated. This, along with a hybrid siliciclastic-volcaniclastic (tuffitic) character of the Zinkgruvan ore host, confirms earlier interpretations that the Zinkgruvan deposit formed in an actively subsiding basin, distal to active volcanic centers in the BLU in the time range 1.90–1.89 Ga. Our results support models suggesting that basinal brine-driven hydrothermal systems in sedimentary basins distal to volcanic centers could form world-class Zn deposits as early as c. 1.90 Ga.
|
|
| 8. |
|
|
| 9. |
- Melero-Asensio, I., et al.
(författare)
-
Geophysical signature of Malingen, the minor crater of the Lockne-Malingen doublet impact structure
- 2018
-
Ingår i: Meteoritics & Planetary Science. - : Wiley. - 1086-9379 .- 1945-5100. ; 53:7, s. 1456-1475
-
Tidskriftsartikel (refereegranskat)abstract
- Malingen is the 0.7km wide minor crater associated to the 10 times larger Lockne crater in the unique Lockne-Malingen doublet. The craters formed at 458Ma by the impact of a binary asteroid related to the well-known 470Ma Main Belt breakup event responsible for a large number of Ordovician craters and fossil meteorites. The binary asteroid struck a target sequence including similar to 500m of sea water, similar to 80m of limestone, similar to 30m of dark mud, and a peneplainized Precambrian crystalline basement. Although the Lockne crater has been extensively studied by core drillings and geophysics, little is known about the subsurface morphology of Malingen. We performed magnetic susceptibility and remanence, as well as density, measurements combined with gravity, and magnetic field surveys over the crater and its close vicinity as a base for forward magnetic and gravity modeling. The interior of the crater shows a general magnetic low of 90-100nT broken by a clustered set of high-amplitude, short wavelength anomalies caused by bodies of mafic rock in the target below the crater and as allogenic blocks in the crater infill. The gravity shows a general -1.4mgal anomaly over the crater caused by low-density breccia infill and fractured crystalline rocks below the crater floor. The modeling also revealed a slightly asymmetrical shape of the crater that together with the irregular ejecta distribution supports an oblique impact from the east, which is consistent with the direction of impact suggested for the Lockne crater.
|
|
| 10. |
- Peillod, Alexandre, 1998-
(författare)
-
How were high-pressure rocks exhumed in Naxos, Greece?
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Combining petrological and geochronological data we were able to show that rocks in south Naxos completed a full blueschist-/greenschist-facies metamorphic loop in about 10 Myr, distinctly faster than hitherto believed. We show that the high-pressure rocks reached peak pressure (16.3±0.9 kbar - 619 ±32°C) between 40.5±1.0 and 38.3±0.5 Ma and were re-equilibrated in the middle crust (3.8±1.1 kbar - 384±30 °C) under greenschist-facies metamorphism during in the Oligocene ~32 Ma. Our data indicate that this exhumation occurred at rates of 7.4±4.6 km Ma-1. Therefore, the Oligocene greenschist-facies overprint of the blueschist-facies rocks from south Naxos is unrelated to the Miocene amphibolite-/greenschist-facies metamorphism observed in Naxos.
|
|
