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Titolo:
Source, transport, and weathering influences upon grain-size and heavy mineral trends in glacial deposits of southwestern Sweden
Autore:
Lang, LO; Stevens, RL;
Indirizzi:
Geol Survey Sweden, SE-41320 Gothenburg, Sweden Geol Survey Sweden Gothenburg Sweden SE-41320 E-41320 Gothenburg, Sweden Univ Gothenburg, Dept Earth Sci, SE-40530 Gothenburg, Sweden Univ Gothenburg Gothenburg Sweden SE-40530 , SE-40530 Gothenburg, Sweden
Titolo Testata:
GFF
, volume: 121, anno: 1999,
parte:, 2
pagine: 145 - 153
SICI:
1103-5897(199906)121:<145:STAWIU>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
FOREST SOILS; AREA; SANDSTONES;
Keywords:
heavy minerals; provenance; selective sorting; weathering; mineral stability; till; glaciofluvial; southwestern Sweden;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
56
Recensione:
Indirizzi per estratti:
Indirizzo: Lang, LO Geol Survey Sweden, Guldhedsg 5A, SE-41320 Gothenburg, Sweden Geol Survey Sweden Guldhedsg 5A Gothenburg Sweden SE-41320 weden
Citazione:
L.O. Lang e R.L. Stevens, "Source, transport, and weathering influences upon grain-size and heavy mineral trends in glacial deposits of southwestern Sweden", GFF, 121, 1999, pp. 145-153

Abstract

Heavy mineral variability and regional trends are interpreted in terms of sediment source, transport sorting and weathering processes at 22 sites in tills, glaciofluvial deposits and reworked sediments in southwestern Sweden. Heavy minerals make up 4-11% of the coarse-silt fraction (45-63 mu m) of the tills and reworked sediments, while significant enrichment (up to 100%)has occurred in glaciofluvial deposits. The most abundant minerals are hornblende and epidote. Minor amounts of apatite, garnet, titanite, and zirconare usually present. The geographic distribution of the heavy minerals relates to three factors. The local Precambrian bedrock has considerable amounts of metamorphic minerals, such as epidote, due to repeated periods of low-grade metamorphism. Secondly, mineral sorting during sediment transport and deposition has enriched heavy minerals within individual deposits and specific fractions. Finally, chemical and physical weathering of the surficialsediments has selectively depleted certain mineral amounts now present in the upper part of the soil profiles. In contrast, the heavy mineral assemblages in the lower B horizons are only slightly different from those in C horizons in both tills and reworked sediments, allowing the combined use of these horizons in regional interpretations of source character. Consistent with regional metamorphic trends in the bedrock, the ratio of epidote to hornblende in tills is up to 10 times greater in northern parts of the former county of Alvsborg compared to south-central areas. Sediment sorting and stratigraphic heterogeneity limit validity of mineral comparison with glaciofluvial deposits. Heavy minerals are an essential source for acid neutralization and long-term nutrient supply in forest ecosystems. The correlation ofmineralogy to bedrock sources and the compositional modification through sedimentologic processes are necessary parameter improvements in total ecological modelling.

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Documento generato il 03/12/20 alle ore 15:58:10