Depletion-induced seismicity in NW-Germany: lessons from comprehensive investigations     

Gudehus  Gerd  Lempp  Christof  Scheffzük  Christian  Műller  Birgit I.  Schilling  Frank R. 《Acta Geotechnica》2023,18(2):951-969

Acta Geotechnica - Evaluating various investigations for north-German gas fields, we discuss past and actual evolutions of the rock fabric in the light of dilatant driven and spontaneous...  相似文献   

Landslide cost modeling for transportation infrastructures: a methodological approach     

Martin Klose  Bodo Damm  Birgit Terhorst 《Landslides》2015,12(2):321-334

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Advances in understanding calcite varve formation: new insights from a dual lake monitoring approach in the southern Baltic lowlands     

Patricia Roeser  Nadine Dräger  Dariusz Brykała  Florian Ott  Sylvia Pinkerneil  Piotr Gierszewski  Christin Lindemann  Birgit Plessen  Brian Brademann  Michał Kaszubski  Michał Fojutowski  Markus J. Schwab  Michał Słowiński  Mirosław Błaszkiewicz  Achim Brauer 《Boreas: An International Journal of Quaternary Research》2021,50(2):419-440

We revise the conceptual model of calcite varves and present, for the first time, a dual lake monitoring study in two alkaline lakes providing new insights into the seasonal sedimentation processes forming these varves. The study lakes, Tiefer See in NE Germany and Czechowskie in N Poland, have distinct morphology and bathymetry, and therefore, they are ideal to decipher local effects on seasonal deposition. The monitoring setup in both lakes is largely identical and includes instrumental observation of (i) meteorological parameters, (ii) chemical profiling of the lake water column including water sampling, and (iii) sediment trapping at both bi-weekly and monthly intervals. We then compare our monitoring data with varve micro-facies in the sediment record. One main finding is that calcite varves form complex laminae triplets rather than simple couplets as commonly thought. Sedimentation of varve sub-layers in both lakes is largely dependent on the lake mixing dynamics and results from the same seasonality, commencing with diatom blooms in spring turning into a pulse of calcite precipitation in summer and terminating with a re-suspension layer in autumn and winter, composed of calcite patches, plant fragments and benthic diatoms. Despite the common seasonal cycle, the share of each of these depositional phases in the total annual sediment yield is different between the lakes. In Lake Tiefer See calcite sedimentation has the highest yields, whereas in Lake Czechowskie, the so far underestimated re-suspension sub-layer dominates the sediment accumulation. Even in undisturbed varved sediments, re-suspended material becomes integrated in the sediment fabric and makes up an important share of calcite varves. Thus, while the biogeochemical lake cycle defines the varves’ autochthonous components and micro-facies, the physical setting plays an important role in determining the varve sub-layers’ proportion.  相似文献   

Using variations in the stable carbon isotope composition of macrophyte remains to quantify nutrient dynamics in lakes     

Ulrike Herzschuh  Steffen Mischke  Hanno Meyer  Birgit Plessen  Chengjun Zhang 《Journal of Paleolimnology》2010,43(4):739-750

The apparent isotope enrichment factor ε_macrophyte of submerged plants (ε_{macrophyte–DIC} = δ¹³C_macrophyte − δ¹³C_DIC) is indicative of dissolved inorganic carbon (DIC) supply in neutral to alkaline waters and is related to variations in aquatic productivity (Papadimitriou et al. in Limnol Oceanogr 50:1084–1095, 2005). This paper aims to evaluate the usage of ε_macrophyte inferred from isotopic analyses of submerged plant fossils in addition to analyses of lake carbonate as a palaeolimnological proxy for former HCO₃ ⁻ concentrations. Stable carbon isotopic analysis of modern Potamogeton pectinatus leaves and its host water DIC from the Tibetan Plateau and Central Yakutia (Russia) yielded values between −23.3 and +0.4‰ and between +14.0 and +6.5‰, respectively. Values of ε _{Potamogeton–DIC} (range −15.4 to +1.1‰) from these lakes are significantly correlated with host water HCO₃ ⁻ concentration (range 78–2,200 mg/l) (r = −0.86; P < 0.001), thus allowing for the development of a transfer function. Palaeo-ε _{Potamogeton–ostracods} values from Luanhaizi Lake on the NE Tibetan Plateau, as inferred from the stable carbon isotope measurement of fossil Potamogeton pectinatus seeds (range −24 to +2.8‰) and ostracods (range −7.8 to +7.5%) range between −14.8 and 1.6‰. Phases of assumed disequilibrium between δ¹³C_DIC and δ¹³C_ostracods known to occur in charophyte swards (as indicated by the deposition of charophyte fossils) were excluded from the analysis of palaeo-ε. The application of the ε _{Potamogeton–DIC}-HCO₃ ⁻ transfer function yielded a median palaeo-HCO₃ ⁻ -concentration of 290 mg/l. Variations in the dissolved organic carbon supply compare well with aquatic plant productivity changes and lake level variability as inferred from a multiproxy study of the same record including analyses of plant macrofossils, ostracods, carbonate and organic content.  相似文献   

Late Pleistocene genesis of the middle Yarlung Zhangbo Valley,southern Tibet (China), as deduced by sedimentological and luminescence data     

Knut Kaiser  Zhongping Lai  Birgit Schneider  Frank W. Junge 《Quaternary Geochronology》2010,5(2-3):200-204

Knowledge on valley formation and palaeohydrology of the Yarlung Zhangbo (named Brahmaputra south of the Himalayas) is still in an early stage. Research was conducted in the middle valley reach around Gonggar in order to investigate the sediment properties, age and palaeoenvironmental implication of a widespread aggradational valley terrace. This heavily dissected terrace, lying c. 25 m above the present floodplain, consists of topping aeolian and colluvial deposits, intermediate lacustrine fines and basal fluvial sands. Sedimentological properties of the lacustrine layers suggest a cold-climate depositional environment. Geochemical data refer to a common provenance of all sediments investigated from a regional catchment area, implying a local provenance of topping loesses and sands by aeolian sorting of nearby fluvial deposits. OSL dates, representing the first luminescence dating effort partly applied to non-aeolian sediments in this valley, cluster closely in the interval 11.7 ± 0.8–17.4 ± 1.4 ka. During the Late Pleistocene (until c. 16 ka) the investigated middle valley reach around Gonggar was occupied by a lake attaining an extension of at least 100 km.  相似文献   

Aquatic macrophyte dynamics in Lake Karakul (Eastern Pamir) over the last 29 cal ka revealed by sedimentary ancient DNA and geochemical analyses of macrofossil remains     

Liv Heinecke  Laura S. Epp  Maria Reschke  Kathleen R. Stoof-Leichsenring  Steffen Mischke  Birgit Plessen  Ulrike Herzschuh 《Journal of Paleolimnology》2017,58(3):403-417

Due to methodological challenges there are only a few studies that focus on macrophyte dynamics in large lakes despite their notable role in a lake’s ecosystem functioning. This study investigates composition and productivity changes of the submerged vegetation of Lake Karakul, Pamir Mountains (Tajikistan), using sedimentary ancient DNA metabarcoding and elemental (C/N) and isotopic (δ¹³C, δ¹⁵N) measurements of Stuckenia cf. pamirica (Baagøe) Z. Kaplan (Potamogetonaceae) leaf remains. No Stuckenia cf. pamirica leaf remains were found for 28.7–26.1 cal ka BP, when both Potamogetonaceae and Chara (L.) DNA sequences were recorded, suggesting sparse submerged vegetation at the coring site. This agrees with the inference of a deep lake reached using geochemical proxies. From 26.1 to 17.5 cal ka BP a few macrophyte remains and high numbers of Potamogetonaceae sequences were recovered: lake level was probably low, as suggested by other studies on the lake. Another phase of increased numbers of Chara sequences and the absence of Stuckenia cf. pamirica leaf remains was found between 17.5 and 12.2 cal ka BP, which coincides with a lake-level transgression at Lake Karakul as indicated by paleo-shoreline investigations. Analyses of macrophyte remains reveal intermediate paleo-productivity from 6.9 cal ka BP and high paleo-productivity from 2.2 cal ka BP onwards. From comparisons with other studies, we suggest that lake-level changes are the main driver for the submerged vegetation composition and productivity at the coring site in Lake Karakul and underline our conclusions by depicting the present-day distribution of Stuckenia cf. pamirica and Chara within the lake.  相似文献   

Editorial: Acta hydrochim. hydrobiol. 6/2006     

Fritz H. Frimmel  Birgit C. Gordalla 《洁净——土壤、空气、水》2006,34(6):519-521

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Variation in Lake Baikal's phytoplankton distribution and fluvial input assessed by SeaWiFS satellite data   总被引：1，自引：0，他引：1  

Birgit Heim  Hedi Oberhaensli  Susanne Fietz  Hermann Kaufmann 《Global and Planetary Change》2005,46(1-4):9

The current behaviour of selected climate proxies in Lake Baikal was assessed by remote sensing analyses of ‘Sea viewing Wide Field of view Sensor’ (SeaWiFS) satellite data. Suitable proxies include optically visible water constituents such as phytoplankton, suspended terrigenous matter and yellow substance. These limnological parameters reflect the present-day climate bioproductivity and the river discharge in the catchment area.A biological and geochemical ground truth data set for Lake Baikal was established with the help of members of the paleoclimate project ‘high-resolution CONTINENTal paleoclimate record in Lake Baikal’ (CONTINENT). For processing the SeaWiFS satellite data, the atmospheric correction was adapted to the case of Lake Baikal. Chlorophyll as a proxy for phytoplankton was quantified using global NASA ocean colour algorithms OC2 and OC4. In cases of no optical interferences by terrigenous input, the calculated chlorophyll concentrations in clear pelagic waters were within ±30% accuracy with the CONTINENT cruise data during the summers of 2001 and 2002. Within this range of accuracy, the SeaWiFS time series will be able to show the seasonal variations of chlorophyll of specified bio-optical provinces of Lake Baikal and of CONTINENT sites. In this study, the suspended matter as a proxy for the terrigenous input was calculated according to an empirical algorithm using ground truth data in the time frame of flooding events in summer 2001. The approach chosen correlates the suspended matter concentration with the remotely sensed parameter of ‘attenuation coefficient’ to account for the organic-rich terrigenous input that originates from the swampy watersheds.Seasonal and spatial information that is provided by the analyses of the SeaWiFS satellite data will assist paleoclimate researchers to interpret the autochthonous and allochthonous influences at the CONTINENT coring sites.  相似文献   

Quantitative assessment of information quality in textual sources for landslide inventories     

Kreuzer  Thomas M.  Damm  Bodo  Terhorst  Birgit 《Landslides》2022,19(2):505-513

Landslide research chiefly relies on digital inventories for a multitude of spatial, temporal, and/or process analyses. In respect thereof, many landslide inventories are populated with information from textual documents (e.g., news articles, technical reports) due to effectiveness. However, information detail can vary greatly in these documents and the question arises whether such textual information is suitable for landslide inventories. The present work proposes to define the usefulness of textual source types as a probability to find landslide information, weighted with adaptable parameter requirements. To illustrate the method with practical results, a German landslide dataset has been examined. It was found that three combined source types (administrative documents, expert opinions, and news articles) give an 89 % chance to detect useful information on three defined parameters (location, date, and process type). In conclusion, the definition of usefulness as a probability makes it an intuitive, quantitative measure that is suitable for a wide range of applicants. Furthermore, a priori knowledge of usefulness allows for focusing on a few source types with the most promising outcome and thus increases the effectiveness of textual data acquisition and digitalisation for landslide inventories.

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Late Palaeozoic red beds elucidate fluvial architectures preserving large woody debris in the seasonal tropics of central Pangaea     

Steffen Trümper  Birgit Gaitzsch  Jörg W. Schneider  Bodo-Carlo Ehling  Reinhard Kleeberg  Ronny Rößler 《Sedimentology》2020,67(4):1973-2012

Fluvial red beds containing anatomically preserved large woody debris shed new light on seasonally dry biomes of the Pennsylvanian–Permian transition and elucidate the concurrence of river depositional systems and vegetation. As a result, the occurrence, distribution and preservation of petrified large woody debris accumulations are considered crucial to understanding the role of arborescent vegetation in shaping fluvial environments. This study reports sizeable silicified trunks and corresponding fluvial architectures from the uppermost Pennsylvanian (upper Gzhelian) Siebigerode Formation (Kyffhäuser, central Germany). The origin, taphonomy and depositional environment of the fossil woods are elucidated by using a multidisciplinary approach including geological mapping, lithofacies analysis, sediment petrography, wood anatomical studies and microstructure analyses. Results reflect the gradual burial of a gentle basement elevation by sand-bed to gravel-bed braided rivers at the north-western margin of the perimontane Saale Basin. Facies architectures resulted from a complex interplay of syndepositional tectonics, repeated palaeorelief rejuvenation, high-frequency channel avulsion, seasonally dry climate and woody debris–sediment interactions. The alluvial influx and cut-bank erosion recruited trunks from adjacent semi-riparian slope habitats vegetated by up to 40 m tall cordaitaleans and conifers. High discharge in wide braids facilitated uncongested transport of large woody debris. Trunk entombment and initial preservation resulted from grounding on barforms, anchoring by attached roots and subsequent burial. The post-depositional two-phase silicification was influenced by hydrothermal hematite mineralization and determined a selective wood preservation pattern known as ‘pointstone’. Large woody debris-induced sedimentary structures (‘LWDISS’) are introduced as a class of sediment structures formed by the biogenic impact on terrestrial deposition.  相似文献