Strážnické Pomoraví—Holocene Evolution of a Unique Floodplain and Aeolian Landforms

Máčka, Zdeněk; Kadlec, Jaroslav

doi:10.1007/978-3-319-27537-6_28

Cited by 2 publications

(1 citation statement)

References 9 publications

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“…V prvé řadě je to systém protipovodňových hrází vybudovaný před II. světovou válkou, který zmenšil rozsah povodňových inundací na cca 25 % původní plochy (Máčka, Kadlec 2016). Druhým faktorem je nadměrné zahloubení koryta vyvolané inženýrskými úpravami, které způsobuje, že do nivy se rozlévají teprve povodně s pětiletým a vyšším intervalem opakování (Brázdil et al 2011).…”

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Vliv sedimentačního prostředí na magnetickou susceptibilitu přelivových sedimentů nivy Moravy ve Strážnickém Pomoraví

Ježková

Máčka

2020

Geologické výzkumy

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Four profiles in different sedimentary environments - natural levee, proximal floodplain, distal floodplain, oxbow lake - were sampled to obtain magnetic susceptibility (MS), grain size, organic matter content (LOI) and pH. Relationships between selected parameters (χlf, D50, LOI, pH) were analysed by means of statistical analysis (linear regression, PCA, factor analysis). Principal goal was to investigate how character of individual sedimentary environments and their distance from the active river channel is reflected in the magnetic signal of overbank deposits. A decrease in the magnetic signal with increasing distance from the river channel was shown, confirming that fluvial deposition is a major factor of contamination of floodplain sediments by anthropogenic magnetic particles. The base of elevated values of MS (levee: 80 cm, proximal floodplain: 30 cm) probably corresponds to the turn of the 19th and 20th century and the strongest magnetic signal (levee: 32,5 cm, proximal floodplain: 5 cm) belongs to the 1980s. Statistically significant relationships were found between: χlf and LOI (direct dependence), LOI and D50 (indirect dependence), pH and D50 (direct dependence) when data from all profiles were analysed together.

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Section: úVodunclassified

Vliv sedimentačního prostředí na magnetickou susceptibilitu přelivových sedimentů nivy Moravy ve Strážnickém Pomoraví

Ježková

Máčka

2020

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Těžké minerály rozsypových ložisek zlata vázaných na khantaishirský ofiolitový komplex poblíž měst Altaj a Khaliun (jihozápadní Mongolsko)

Buriánek¹,

Svatuška²

2020

Geologické výzkumy

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Detailed morphological and chemical studies of heavy minerals from two localities fluvial sediments in the area of the khantaishir ophiolitic complex near the towns Altai and Khaliun (Southwestern Mongolia) allowed the interpretation possible source region for the gold. The heavy mineral spectrum from the sediments near the Altai town is dominated by magnetite (32 %), chromite (27 %), epidote (11 %), apatite (6 %), and clinopyroxene (5 %). We assume that these minerals come from the ultrabasic and basic igneous rocks in the Neoproterozoic khantaishir ophiolitic complex. The relatively undeformed and three-dimensional shape of gold particles indicating short distance their transport. Rare is native gold enclosed in dolomite or quartz, which indicates that potential gold sources are listvenite. The heavy mineral spectrum from the fluvial sediments in the small creek near the Khaliun town is different. The studied sample includes magnetite (31 %), amphibole (19 %), zircon (18 %), pyrite (13 %), apatite (5 %), epidote (4 %), titanite (4 %), clinopyroxene (2 %), monazite (1 %), ilmenite (1 %), garnet (1 %), and barite (0.1 %). Large variations in the mineral composition heavy mineral spectrum indicate a wide source area which includes basic to intermediate igneous rocks Cambrian-Ordovician Ikh-Mongol Arc System and medium-grade metamorphic rocks (metapelite). The subspherical rounded shape of the gold particles indicates fluvial transport. In the case of small and geologically simple drainage area as creek near the Altai town represents heavy minerals a good tool for determination of the origin of placer gold. There is a contrast between the heavy mineral spectrum from the localities near the Altai and Khaliun towns. The shape of gold particles as well as a simple heavy mineral spectrum from sediments near the Altai indicates short transport from the limited draining area (approximately 6 km2). Gold probably originating from the ultramafic rocks (listvenite), according to associated dolomite and simple spectrum of heavy minerals. Whereas the origin of gold from the placer deposits near Khalinun remains unclear and most probably could originate from the hydrothermal veins in intermediate or basic igneous rocks (presence of barite associated with abundant pyrite).

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Strážnické Pomoraví—Holocene Evolution of a Unique Floodplain and Aeolian Landforms

Cited by 2 publications

References 9 publications

Vliv sedimentačního prostředí na magnetickou susceptibilitu přelivových sedimentů nivy Moravy ve Strážnickém Pomoraví

Vliv sedimentačního prostředí na magnetickou susceptibilitu přelivových sedimentů nivy Moravy ve Strážnickém Pomoraví

Těžké minerály rozsypových ložisek zlata vázaných na khantaishirský ofiolitový komplex poblíž měst Altaj a Khaliun (jihozápadní Mongolsko)

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