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| 2. |
- Holm, Einar, et al.
(författare)
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Tid för arbete
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Holme, Kirsten
(författare)
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Geochemical Development of Proterozoic Granites in the SW Baltic Shield
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The plutonic rocks in the Western Segment of the Southwestern Swedish Gneiss Complex show a distinct geochemical evolution. The 1.6 Ga Åmål granitoids and Slottsbron migmatites are a quartz dioritic to granodioritic, calc-alkaline rock suite with smooth, but somewhat fractionated, REE and other trace-element patterns. The younger microcline granites of the 1.5 Ga and 1.3 Ga generations are evolved rocks having fractionated REE patterns with deep negative Eu anomalies. The 1.5 Ga granites vary from calc-alkalic, metaluminous granodiorites to evolved alkali-calcic peraluminous leucogranites. The REE and other trace-element patterns are less evolved than those of the 1.3 Ga rocks. The 1.3 Ga granites are the most evolved intrusions in the area. Granites with a bimodal geochemical character occur. All rocks can be ascribed to one of three types: i. The HUS1 type is homogeneous, alkali-calcic with high SiO2 content and is often leucocratic. ii. The SS2 type has a large geochemical variation, but shows regular inter-element relationships. It is alkali-calcic and has the most evolved REE patterns. iii. In the TYP3 type, calc-alkaline compositions are common. They are the least evolved rocks of this generation. The differences within the 1.3 Ga generation itself are partly due to a variety of source rocks, but also to different melting conditions. The chemical variation suggests that the SS2 type formed at deeper levels than the HUS1 and 1.5 Ga granites. The degree of melting was probably also higher than for the two latter types. The TYP3 rocks are likely to have formed at shallow levels, but with a higher degree of melting than the HUS1 rocks. A model based on isotopic, major- and trace-element data is consistent the theory that rocks similar to the Åmål granitoids are the source rock for the HUS1 type but not for the SS2 type. The epsilonNd(1.3) values for one of the HUS1-type rocks are, however, outside the known range of the time integrated epsilonNd(1.3) for the Åmål granitoids and could have a more primitive origin. Rocks from the Eastern Segment differ from those of the WS. The 1.7 Ga Mårdaklev granite has an evolved appearance similar to the HUS1 type, but no coeval rocks in the WS have this characteristic. The compositions of the 1.4 TTK intrusions vary between monzonite and granite - a trend not found in the Western Segment. The differences in geochemical character reflect differences in geological settings. The TTK intrusions of the Eastern Segment are interpreted to have formed at deep levels in a thicker and more evolved continental crust than the roughly coeval granites in the Western segment. The calc-alkaline character of the 1.6 Ga generation rocks suggests a less evolved, subduction related setting. The younger granites are derived from ensialic crust and variations in composition are interpreted to reflect different source rocks and different levels of magma generation. This investigation supports earlier suggestions that the evolutions of the Eastern and Western Segments were separate before Sveconorwegian time.
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| 5. |
- Schunnesson, Håkan, et al.
(författare)
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Drill monitoring for geological mine planning in the Viscaria copper mine, Sweden
- 1997
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Ingår i: CIM bulletin. - 0317-0926 .- 1718-4169. ; 90:1013, s. 83-89
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- When mining high grade, narrow ore bodies, the mining method often implies a very detailed knowledge of the ore contacts to avoid unacceptable ore loss and waste rock dilution. During the past decade, the use of microprocessor based drill monitoring equipment has become an accepted technique, even for percussive drilling. On the basis of the recorded drill performance, such as penetration rate, torque pressure, thrust etc., a fast evaluation of the lithological sequence of the ore zone can be made. In order to evaluate the potential of percussive drill monitoring to provide detailed information of the geometry of the ore body, the technique was tested in the Viscaria copper mine in Sweden during 1996. To provide understandable information to the mine geologist, great emphasis was placed on the separation between the drilling response generated by variations in rock conditions from variations caused by the operator and the drill system. Due to the complicated geology in Viscaria, the drilling response presented to the geologists was separated in two independent signals, one representing the hardness of the rock and one representing the inhomogeneity (fracturing) of the rock. With those signals a good separation between different rock types in the ore horizon was achieved. The experience from the Viscaria copper mine is that drill monitoring not only can be used to locate contacts between rock types, but also to characterize rock conditions and, often, also to specify the exact rock type present. Because it is possible to get the drill monitoring information very quickly it is a valuable complement to diamond drilling for increasing the specific knowledge of the geology and the ore body.
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