Forschung - research


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Facies architecture and paleoecology of a Devonian reef at the Klutert Cave, Ennepetal
The middle Devonian is well known for its coral-stromatoporoid reefs. Klutert Cave comprises a three dimensional, stratigraphically thin Givetian (387—382 Ma) reefal autoparabiostrome. Recently cleaned cave walls expose a unique study area (ca. 26,000 m2) for solid taxonomy of the reefal biota and allow high-resolution facies mapping of the cave walls. For evidence of biological self-organization, which - according to the working hypothesis - results from the interaction of consumers (stromatoporids, tabulate and rugose corals) and resources, in this case, nutrients, light availability, growth space, etc, it is intended to numerically test the outcrops. Therefore, detailed field work will aid in understanding the internal reef architecture, its biodiversity and paleoecology and the organismal response to sediment stressed environment. Analysis of clay minerals and provenance of fine-grained clastic material of the matrix assists further in determining the sediment influx. The project is implemented in close cooperation with "Kluterthöhle & Freizeit Verwaltungs- und Betriebs-GmbH & Co. KG" and "Arbeitskreis Kluterthöhle e.V."
Staff involved: T. Unger, A. Immenhauser, S. Riechelmann, R. Hoffmann, M. Aretz (Toulouse), S. Lokier (Bangor), S. Purkis (Miami), S. Voigt (Ennepetal)

Controls on saddle dolomite formation
Saddle dolomites are Mg-carbonates with conspicuously warped crystal surfaces. Previous work has assigned saddle dolomites to the burial realm and fluid temperatures above 60°C. The crystallographic drivers, however, of the warped crystal surfaces are at present unknown. The project makes use of natural saddle dolomites and employs a series of analytical (geochemical and optical tools) to unravel the reasons for this peculiar feature.
Staff involved: Yifan Zhang, M. Müller, S. Chakraborty, A. Immenhauser

The four major Isotopes of Dolomite (C, O, Mg, Ca): Closing the Calcium Isotope (δ44/42Ca) Gap
Dolomite is a rock forming mineral that consists of calcium, magnesium and carbonate ions and naturally occurs in a variety of sedimentological and diagenetic environments. However, data on the calcium isotope signatures of dolomites remain scarce. This is relevant as non-stoichiometric dolomites, the bulk of dolomites in Earth’s history, are often Ca-rich (molar ratio of Ca:Mg>1) and hence, Ca isotope (δ44/40Ca or δ44/42Ca) signatures clearly deserve attention. Previous work documented that the δ44/42Ca, δ26Mg, δ13C, and δ18O isotope signatures of a variety of early diagenetic dolomites/dolostones represent distinct diagenetic domains and time intervals. It is the objective of the project to (i) establish a well-constrained characterization of Ca isotope signatures for early diagenetic dolomite types, (ii) combine multi-proxy Ca, Mg, C, O (and stable Sr) isotope data in order to reduce noise and enhance signal in data sets by assessing covariance patterns and (iii) assess the formation and diagenetic alteration of different stoichiometric dolomite types and their isotopic and elemental patterns relative to syn-sedimentary non-stoichiometric phases. Overall, it is the aim to provide the community with the foundations to establish a well-constrained palaeo-seawater archive.
Staff involved: L. Belohlavek, S. Riechelmann, M. Dietzel,
V. Mavromatis, V. Liebetrau, A. Immenhauser


Modern seawater properties and early marine cementation at Abu Dhabi coast
In the modern glacial world, the (sub)tropical Abu Dhabi coastal area represents one of the few analogues for ancient epeiric seas. The coastal area is characterized by hot and arid climate, shallow water depth, low topographic gradient, little terrestrial influx and active carbonate sedimentation. Furthermore, there are widespread and diverse early-marine cementation features in the Abu Dhabi coastal area. Therefore, the (sub)tropical active carbonate environment of the Abu Dhabi coast provides a unique opportunity to study: i) spatial variation and evolution of epeiric seawater properties and related geochemical proxies; ii) modern early-marine cemented features in the epeiric seas, and iii) the relationship between seawater properties and early-marine cementation. These aspects are relevant for the interpretation and reconstruction of paleo-marine environments from past epeiric carbonates.
Staff involved: Christine Zhong, Yuzhu Ge, Chelsea Pederson, Stephen Lokier, Adrian Immenhauser

DGE-rollout of deep-geothermal energy in NW-Europe

In an effort to reduce CO2 emission in NW Europe, the exploration of deep geothermal energy (DGE) production to replace electricity and heat by burning fossil fuels is being researched through an EU-funded Interreg project called DGE-Rollout. However, the exploration of DGE in most NWE regions requires specific expertise and technologies in the complex geological situations (strongly faulted high permeable carbonates and coarse clastic rocks) that lie across the borders between Germany, France, the Netherlands and Belgium. It is the objective of DGE-Rollout to produce energy and reduce CO2 emissions by replacing fossil fuels through the increased usage of DGE in NWE for large-scale infrastructures requiring high-temperature heat supplies to cover their basic energy loads. This will be achieved by mapping and networking, by the application of innovative decision, exploration strategies, and testing for production optimization. Further activities will apply innovative decision and exploration strategies that cost less, reduce risks, are more reliable and will show a 3D Atlas of the complex geological situation as the spatial basis usable for DGE. RUB will focus on working to better understand the response of the potential DGE reservoir unit, and help predict the evolution of the reservoir during production.
Staff involved: Chelsea Pederson and Adrian Immenhauser

External link: DGE-rollout of deep-geothermal energy in NW-Europe

Greener - Characterization and prioritization of geothermal reservoirs as energy carriers in the Rhine-Ruhr area
The conversion of the district heating network in the Rhine-Ruhr area from being fossil-fueled to being supplied by renewable energy carriers is a major task. Integrating deep geothermal reservoirs into the grid could provide the future solution. Potential geological formations in the Rhine-Ruhr area include the Carboniferous and Devonian carbonates at depths of 3,000 m to 5.000 m. The research project Greener aims to identify the spatial distribution of the Devonian reef-facies in the Rhine-Ruhr area and its respective geoscientific properties. An outcrop analogue study is conducted which includes field research like fault and fracture analysis etc. and subsequent laboratory examinations analyze the thermal, hydraulic, mechanical and chemical properties of the aforementioned stratigraphic units under surface and reservoir conditions. These correlations provide valuable information about the rock characteristics at a certain depth and thus the overall reservoir potential of the Devonian carbonates.
Staff involved: K. Lippert, A. Immenhauser, R. Bracke, M. Nehler

Relation between carbonate rock properties and fracture patterns in limestone-to-dolostone transition intervals
Understanding the relation between carbonate facies at deposition and its subsequent diagenetic pathways on one side and fracturing of these rocks during subsidence or exhumation is important. From a fluid circulation point of view, obtaining wholesale dolomitization of large bodies of rocks is not obvious as it requires a combination of flow along fractures/faults and through the country rock itself. If pathways provided by fracture networks are too efficient, fluids would not diffuse significantly inside the rock thereby only causing dolomitization very close to the fractures. The objectives of this study are to characterize and as well to produce a quantitative reconstruction of fracture networks over the full relevant range of scales and at the same time propose a model that describes the transformation in dimension of the clasts in a fault damage zone of carbonate rocks from cubic to roundness in quantitative terms. Secondly, we will perform numerical simulations testing the relative role of fractures and rock porosity in allowing flow. Staff involved: O.A. Igbokwe, M. Müller and A. Immenhauser

Assessing the resilience of carbonate archives of environmental change in limestone-to-dolostone transition zones
About 70% of Earth's geological history is recorded in carbonate archives that have seen varying degrees of post-depositional dolomitization. Limestone-to-dolostone transition zones are important due to the inherent depositional and diagenetic information they contain. The insufficient understanding of lateral and stratigraphic patterns within these transition zones forms a limitation in carbonate research. Similarly, early diagenetic dolomicrites, which typically record marine environmental conditions, are in the focus of this project. When altered, burial conditions may overprint the original signature but then at least provide information on burial pathways. The objective of this study is to establish a detailed framework for limestone-to-dolostone transition zones and early diagenetic dolomites from different time intervals. Upstream, a well-constrained Mg-isotope data set from all early (marine) to late diagenetic (burial) carbonate phases and complementary geochemical data constrained within fluid property context are aimed for. In foresight, this project intends to establish robust and quantitative benchmarks to test the validity of various environmental proxies in dolomitized limestones and their associated facies. Staff involved: M. Müller and A. Immenhauser

QUEST - QUantitative palaeoEnvironments from SpeleoThem
QUEST (QUantitative palaeoEnvironments from SpeleoThems) will develop new techniques for extracting quantitative information from speleothems and link field and laboratory experiments on water/mineral chemistry with innovative physical and numerical analyses on speleothems. The combination of these techniques, based on physical and chemical properties and statistical methods, will allow us to deliver quantitative reconstructions of two key parameters: hydrology and temperature. We will test our methods using speleothems from Australasia, a region vulnerable to El Niño-Southern Oscillation (ENSO) variability. At present, there is a relative dearth of millennial-scale palaeoclimate data from this region.
Our team members come from a variety of backgrounds including environmental chemistry, environmental mineral magnetism, and numerical data analysis. Each group within the team has already begun developing innovative methods for palaeoclimate reconstruction within their own subfield, but this project will be the first time these methods are combined and applied collectively to speleothems. Our combination of interdisciplinary expertise, state-of-the-art instrumentation, and novel techniques means that we are ideally placed to develop quantitative climate records from speleothems.
QUEST has received funding from the European Union’s Horizon 2020 Research and Innovation programme under the Marie Skłodowska-Curie grant agreement No 691037.
Staff involved at Bochum: S. Breitenbach

QUEST

Cephalopod shells as marine paleo-environmental recorder
Cephalopod shells record marine seawater properties (e.g., temperature) during growth making them ideal candidates to reconstruct paleo-environments. Due to the accretionary shell growth also ontogenetic changes of the cephalopod habitat are recorded. That allows for the reconstruction of life habits related to different shell morphologies. This project focuses on ammonoids, an extinct cephalopod. During the Cretaceous many transgressions/regressions, warming/cooling phases and oceanic anoxic events take place. Thus, making the Cretaceous ideal for studying the appearance, disappearance and distribution of specific shell morphologies. The main goals are to investigate the possible influence of changes of various paleo-ecological parameters (e.g., water depth, temperature, oxygenation of the habitat zone) on the ammonoid conch geometry. Therefore we apply geochemical analyses (δ18O, δ13C) of pristine preserved shells.

Animated micro-CT of Nautilus pompilius

Staff involved: R. Hoffmann, R.D. Neuser

Magnesium isotope signature of drip and flowing water in a former mine
The goal of this research project is to improve our understanding of the Magnesium isotope system. The former mine at Neubulach (South Germany) is especially suitable for this project, because water percolates through both siliciclastic and carbonate rocks. The differences in the Mg isotope composition between various waters and their variations over time will shed light on the fractionation processes of these rocks during dissolution. This project is undertaken in collaboration with the University Tübingen and the "Stollengemeinschaft der historischen Bergwerke Neubulach e.V". Staff involved: S. Riechelmann, D. Buhl, A. Immenhauser and G. Markl (University Tübingen).

Air and drip water monitoring of Klutert Cave, Ennepetal
Klutert Cave formed in a thin limestone layer with siliciclastic forming the underlying and overlying bed. Monitoring of drip and flowing water will improve the understanding of the hydrological connection of the different waters and their sources. Furthermore, Klutert Cave is a show cave and in order to determine the impact of tourism on the cave atmosphere the CO2-content of the cave air is measured continuously. This project is performed in close collaboration with "Kluterthöhle & Freizeit Verwaltungs- und Betriebs-GmbH & Co. KG" and "Arbeitskreis Kluterthöhle e.V." Staff involved: S. Riechelmann, D. Buhl, A. Immenhauser, S. Voigt (Arbeitskreis Kluterthöhle e.V.)

Magnesium isotope signature of dolomites
The goal of this research project is an improved understanding of the controlling factors of magnesium isotope (δ26Mg) fractionation in for instance speloan carbonates or bivalve hardparts. The main focus is on the potential of this novel isotope system as a paleo-climatological, paleo-ecological and paleo-oceanographic proxy. Staff involved: D. Buhl, A. Immenhauser, D.K. Richter

Cryogenic cave calcites
Cryogenic cave calcites (CCC) grow from freezing cave waters where slow freezing leads to a very light O-isotope composition and quick freezing leads to higher O-isotope composition. Calcites of the first group have formed in Middle European caves in water pools on ice during the transition from cold to warm periods. After the ice had molten, a polymict "crystal sand" of cryogenic calcite particles is found as a residue on the cave ground. According to morphological and structural criteria these particles can be distinguished as spherolitic, rhombohedral crystal, plait and skeletal crystal sinters. Our investigations focus on occurrences of CCC in different european caves. Staff involved: D.K. Richter, R.D. Neuser.