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111.
The Lateglacial and Holocene in Central Europe: a multi‐proxy environmental record from the Bohemian Forest,Czech Republic
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Klára Vočadlová Libor Petr Pavla Žáčková Marek Křížek Lenka Křížová Simon M. Hutchinson Miroslav Šobr 《Boreas: An International Journal of Quaternary Research》2015,44(4):769-784
The Hercynian mountain ranges were islands of mountain glaciation and alpine tundra in a Central European ice‐free corridor during the Late Pleistocene. Today they are notable areas of glacial landforms, alpine‐forest free areas, peatlands and woodlands. However, our knowledge of the Lateglacial and early Holocene environmental changes in this region is limited. We present a new multi‐proxy reconstruction of a mid‐altitude environment in the Bohemian Forest spanning this period. A core (5.2 m length) in the ?erné Lake cirque (1028 m a.s.l.) was subjected to lithological, geochemical, pollen and macrofossil analysis supplemented by two optically stimulated luminescence (OSL) and 10 AMS radiocarbon dates. We determined the impact of regional and supraregional climate changes on the environment. The two most significant changes in sedimentation during the Lateglacial (17.6 and 15.8–15.5 cal. ka BP) were synchronous with regional glacial chronostratigraphy. Unlike Central European mountain ranges, in the Bohemian Forest the Younger Dryas was not coincident with glacier re‐advance, but was a dry, cold episode with low lake levels, which prevailed until the early Preboreal. Plant macrofossils indicate local establishment of Betula nana and Betula pendula/pubescens at 15.4–13.4 cal. ka BP. Comparison with Holocene records from Central Europe shows a similar immigration history of vegetation at mid and higher altitudes. The tree line exceeded an altitude of ~1000 m a.s.l. around 10.5 cal. ka BP and coincided with rapid geochemical changes in the sediment. The 8.2 ka BP event did not have any response in the sedimentary record, but corresponded to stabilization of the Picea abies population and expansion of Fagus. Fagus colonized the Bohemian Forest earlier than other Hercynian mid‐mountains, but never predominated in the composition of the forest at higher elevations. Abies alba was the last tree species that immigrated to the study area. 相似文献
112.
Marcela Laštovičková Karel Klíma Reviewer A. Janáčková 《Studia Geophysica et Geodaetica》1988,32(1):78-83
Summary The new for measuring the electrical conductivity of rocks and minerals developed in the Geophysical Institute is briefly discussed. Unlike the earlier method it uses a PMD-85-1 microcomputer and related equipment (all of CMEA production), which enable the automatic control of the experiment, collection, evaluation, graphic display and storage of the results. This method is verified by measuring the electrical conductivities of granitoids.
am nua m¶rt; uu mn¶rt;mu n¶rt; u ua ¶rt;a uu umumm . muuu m n¶rt;u¶rt; m¶rt;a unm unmPMD-85-1 u nua¶rt;au nuuu ( nu¶rt;ma ), m nm mm amamu nau numa, , am,au uau u anu mam uu. mm m¶rt; nm n uu mn¶rt;muaumu¶rt;.相似文献
113.
Fazel Nasim Berndtsson Ronny Uvo Cintia Bertacchi Madani Kaveh Kløve Bjørn 《Theoretical and Applied Climatology》2018,132(1-2):363-373
Theoretical and Applied Climatology - Lake Urmia in northwest Iran, once one of the largest hypersaline lakes in the world, has shrunk by almost 90% in area and 80% in volume during the last four... 相似文献
114.
115.
Hydroxyl (OH) is one of the few molecules in space showing both maser emission and absorption. In the Milky Way, hydroxyl has been found in various environments such as stellar envelopes, star-forming regions, and HII regions, tracing the physical states of the interstellar medium. Extragalactic OH has been found to provide essential information about the dusty and obscuring material within the inner kiloparsec region of active galaxies. At angular resolution of a few tens of parsecs, OH shows a rather complicated spatial distribution and the interpretation of the circumnuclear environment is rather difficult. Based on results obtained from low- and high-resolution observations, the diagnostic tools of OH will be reviewed and the strategies to further investigate extragalactic OH will be discussed. 相似文献
116.
Summary Mantle-derived xenoliths from Baarley in the Quaternary West Eifel volcanic field contain six distinct varieties of glass
in veins, selvages and pools. 1) Silica-undersaturated glass rich in zoned clinopyroxene microlites that forms jackets around
and veins within the xenoliths. This glass is compositionally similar to groundmass glass in the host basanite. 2) Silica-undersaturated
alkaline glass that contains microlites of Cr-diopside, olivine and spinel associated with amphibole in peridotites. This
glass locally contains corroded primary spinel and phlogopite. 3) Silica-undersaturated glass associated with diopside, spinel ± olivine
and rh?nite microlites in partly to completely broken down amphibole grains in clinopyroxenites. 4) Silica-undersaturated
to silica-saturated, potassic glass in microlite-rich fringes around phlogopite grains in peridotite. 5) Silica-undersaturated
potassic glass in glimmerite xenoliths. 6) Silica-rich glass around partly dissolved orthopyroxene crystals in peridotites.
Geothermometry of orthopyroxene–clinopyroxene pairs (P = 1.5 GPa) gives temperatures of ∼ 850 °C for unveined xenoliths to
950–1020 °C for veined xenoliths. Clinopyroxene – melt thermobarometry shows that Cr-diopside – type 2 glass pairs in harzburgite
formed at 1.4 to 1.1 GPa and ∼ 1250 °C whereas Cr-diopside – type 2 glass pairs in wehrlite formed at 0.9 to 0.7 GPa and 1120–1200 °C.
This bimodal distribution in pressure and temperature suggests that harzburgite xenoliths may have been entrained at greater
depth than wehrlite xenoliths.
Glass in the Baarley xenoliths has three different origins: infiltration of an early host melt different in composition from
the erupted host basanite; partial melting of amphibole; reaction of either of these melts with xenolith minerals. The composition
of type 1 glass suggests that jackets are accumulations of relatively evolved host magma. Mass balance modelling of the type
2 glass and its microlites indicates that it results from breakdown of disseminated amphibole and reaction of the melt with
the surrounding xenolith minerals. Type 3 glass in clinopyroxenite xenoliths is the result of breakdown of amphibole at low
pressure. Type 4 and 5 glass formed by reaction between phlogopite and type 2 melt or jacket melt. Type 6 glass associated
with orthopyroxene is due to the incongruent dissolution of orthopyroxene by any of the above mentioned melts.
Compositional gradients in xenolith olivine adjacent to type 2 glass pools and jacket glass can be modelled as Fe–Mg interdiffusion
profiles that indicate melt – olivine contact times between 0.5 and 58 days. Together with the clinopyroxene – melt thermobarometry
calculations these data suggest that the glass (melt) formed over a short time due to decompression melting of amphibole and
infiltration of evolved host melt. None of the glass in these xenoliths can be directly related to metasomatism or any other
process that occurred insitu in the mantle.
Received November 23, 1999; revised version accepted September 5, 2001 相似文献
117.
Walther Klüpfel 《International Journal of Earth Sciences》1941,32(1-2):178-179
118.
Walther Klüpfel 《International Journal of Earth Sciences》1926,17(6):401-417
Ohne Zusammenfassung 相似文献
119.
Walther Klüpfel 《International Journal of Earth Sciences》1936,27(1):75-76
Ohne Zusammenfassung 相似文献
120.