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Lithologische Beschreibung einer Forschungsbohrung im Zentrum des oberoligozänen, vulkano-lakustrinen Beckens von Enspel/Westerwald (Rheinland-Pfalz; Bundesrepublik Deutschland) (1998)

Felder, Marita ; Weidenfeller, Michael ; Wuttke, Michael

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Publication Date: 2024-05-28

Description: Im Spätsommer 1996 wurde in der oberoligozänen Fossillagerstätte Enspel im nordwestlichen Westerwald vom Geologischen Landesamt Rheinland-Pfalz, gemeinsam mit dem Landesamt für Denkmalpflege Rheinland-Pfalz, eine Forschungsbohrung niedergebracht. Die Bohrung erreichte eine Teufe von 256,3 m. Es wurden 2,6 m Basalt, etwa 137 m lakustrine Sedimente und 90 m Vulkaniklastika erbohrt. An deren Basis folgen fragmentierte devonische Sedimentgesteine, die bis zu einer Mächtigkeit von 24,3 m erbohrt wurden. Die Abfolge repräsentiert die Füllung eines komplexen, maarähnlichen Beckens. Der Bohrkern wird in einem interdisziplinären Projekt von verschiedenen Arbeitsgruppen untersucht, um Bau und Genese des ehemaligen Enspelsees zu erforschen.

Description: Abstract: In late summer 1996 the Geological Survey of Rheinland-Pfalz and the Landesamt für Denkmalpflege Rheinland-Pfalz sank a research core, in the Upper Oligocene Fossillagerstätte Enspel, Northwest-Westerwald-area. The drilling reached a depth of 256.3 m. 2.6 m of basalt, 137 m of lakustrine sediments, 90 m of pyroclastic rocks and 24.3 m of fragmented Devonian sediments were found. This section documents the filling of a complex maarlike basin. The cores are examined in an interdisciplinary research project concerning the genesis and structure of the Enspel lake system.

Description: research

Keywords: ddc:554.3 ; Westerwald ; TK 5313 ; Oligozän ; Bohrung

Language: German

Type: doc-type:article , publishedVersion

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Arsenic-poor fluids promote strong As partitioning into pyrite (2024)

Kutzschbach, M. ; Dunkel, F. ; Kusebauch, C. ; [et al.]

In: Geochimica et Cosmochimica Acta

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Publication Date: 2024-05-28

Description: Pyrite is a ubiquitous sulfide mineral found in diverse geological settings and holds great significance in the formation of Au deposits as well as the safe utilization of groundwater due to its remarkable ability to incorporate substantial amounts of As. However, despite its importance, there remains a dearth of fundamental data on the partitioning of As between pyrite and fluid, which is key for accurately modeling the As distribution in these environments. Here, we present new insights into the partitioning behavior of As between pyrite and fluid at conditions that mimic natural fluid systems. Pyrite was synthesized by replacement of natural siderite in hydrothermal experiments at 200 °C and pH 5 applying a wide range of fluid As concentrations, spanning from 0.001 to 100 µg/g. The As distribution and concentration in synthetic pyrite was analyzed by quantitative LA-ICP-MS mapping providing a high spatial resolution and sensitivity at 2–3 µm image pixel size at a detection limit of ∼1 µg/g at the single pixel scale. Pyrite-fluid partitioning coefficients (DAs(py/fluid)) between synthetic pyrite and experimental fluid agree with previously published data for high fluid As concentrations of 1 µg/g to 100 µg/g (DAs 〈 2000). However, at low As concentrations in the experimental fluid (〈1 µg/g), a steep increase in the DAs(py/fluid) values of up to ∼30,000 was detected, demonstrating even stronger As partitioning into pyrite. This is confirmed by the analyses of natural pyrite that precipitated from As-poor fluids (0.3–0.4 ng/g) within a deep anoxic aquifer in SE Sweden. The discovery holds significant implications for the mobility and scavenging of As, which in turn is important for understanding the formation and fingerprinting of mineral deposits as well as for the secure utilization of groundwater resources.

Language: English

Type: info:eu-repo/semantics/article

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The role of protolith composition in the formation of tin-enriched granitic melts: A modeling study using the example of the southwest China tin province (2024)

Liu, Y. ; Schmidt, C. ; Li, J. ; [et al.]

In: Ore Geology Reviews

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Publication Date: 2024-05-28

Description: Important features of Sn mineralization are the heterogeneous geographic distribution and frequent regional separation from W mineralization in spite some similarities of Sn and W behavior during magmatic processes. Major Sn and W mineralization is often spatially associated with peraluminous granites, which are derived from partial melting of metasediments. Several concepts have been suggested to explain those features, such as a weathering-related Sn-enriched source, Sn redistribution between melts and restite during protolith melting, and extensive fractional crystallization. We demonstrate the importance of protolith composition for the formation of Sn (and W) granites by using a comprehensive bulk-rock composition dataset from Precambrian metasediments of the South China Sn-W province and employing a thermodynamic modeling approach. We used four compositional proxies for phase equilibria calculations, which are the metasediments of the Mengdong, Sibao, Pingbian, and Shuangqiaoshan Groups. It is well documented that those Precambrian metasediments are important protoliths of Sn granites in South China. We present quantitative evaluation of the control of protolith composition in the generation of Sn-enriched granitic melts using South China as example, but our conclusions may also be applicable to worldwide Sn–enriched granites. Our results indicate that the protolith major-element geochemistry controls the anatectic reactions and melt productivity at specific melting conditions, and consequently the partitioning behavior of Sn. Further, pre-enrichment of Sn is crucial to the fertility of granitic melt and may be a prerequisite, particularly for the formation of giant Sn deposits. We propose that the heterogeneous distribution of favorable source rocks is one of the important factors that control the spatial distribution of major Sn (and W) districts in South China and other regions worldwide.

Language: English

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Morpho‐Tectonic Evolution of the Southern Apennines and Calabrian Arc: Insights From Pollino Range and Surrounding Extensional Intermontane Basins (2024)

Clementucci, R. ; Lanari, R. ; Faccenna, C. ; [et al.]

In: Tectonics

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Publication Date: 2024-05-28

Description: The evolution of topography in forearc regions results from the complex interplay of crustal and mantle processes. The Southern Apennines represent a well‐studied forearc region that experienced several tectonic phases, initially marked by compressional deformation followed by extension and large‐scale uplift. We present a new structural, geomorphic and fluvial analysis of the Pollino Massif and surrounding intermontane basins (Mercure, Campotenese and Castrovillari) to unravel their evolution since the Pliocene. We constrain multiple tectonic transport directions, evolution of the drainage, and magnitude and timing of long‐ term incision following base level falls. Two sets of knickpoints suggest two phases of base level lowering and allow to estimate ∼500 m of long‐term uplift (late Pleistocene), as observed in the Sila Massif. On a smaller spatial scale, the evolution and formation of topographic relief, sedimentation, and opening of intermontane basins is strongly controlled by the recent increase in rock uplift rate and fault activity. At the regional scale, an along‐strike, long‐wavelength uplift pattern from north to south can be explained by progressive lateral slab tearing and inflow of asthenospheric mantle beneath Pollino and Sila, which in turn may have promoted extensional tectonics. The lower uplift of Le Serre Massif may be explained as result of weak plate coupling due to narrowing of the Calabrian slab. The onset of uplift in the Pollino Massif, ranging from 400 to 800 ka, is consistent with that one proposed in the southern Calabrian forearc, suggesting a possible synchronism of uplift, and lateral tearing of the Calabrian slab.

Language: English

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Subduction of active spreading ridges and the disappearance of Andean-type cordilleras (2024)

Scalabrino, B. ; Lagabrielle, Y. ; Faccenna, C.

In: Comptes Rendus Geoscience

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Publication Date: 2024-05-28

Description: We address the possible link between the age of subducting oceanic lithosphere and growth of elevated cordilleras versus extension-dominated arc regions. Singularity exists in South America: the lowest elevated Andean segments are found in Patagonia where the active Chile Ridge enters the trench. Subduction of active ridge triggers thermal doming, crustal extension and attenuation of former cordilleras. At the Antarctica–South America connection, three active ridge subductions induced the disruption of a former continuous cordillera during the opening of Drake Passage. Active ridge subduction induces lithosphere thermal erosion and related crustal extension in the upper plate. Evolution of regions worldwide experiencing ridge subduction confirms this hypothesis.

Language: English

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Scheelite composition fingerprints pulsed flow of magmatic fluid in the Fujiashan W skarn deposit, eastern China (2024)

Ji, Y. ; Xie, G. ; Romer, R. ; [et al.]

In: American Mineralogist

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Publication Date: 2024-05-27

Description: Scheelite (CaWO4) is an economically important W mineral in skarns that form when magmatic fluids exsolved from a granitic intrusion react with carbonate wall rocks. In the Fujiashan W skarn deposit, scheelite formed during four stages of the hydrothermal skarn development. We present cathodoluminescence (CL) images and in situ trace element and Sr-O isotope data of scheelite from these four stages, i.e., scheelite in prograde and retrograde skarn, quartz-sulfide veins, and late calcite replacements. Scheelite from prograde skarn and quartz sulfide veins are homogeneous and show oscillatory zoning textures in CL images, whereas scheelite from retrograde skarn and late carbonate stages display dissolution-reprecipitation and patchy textures. The brightness of CL textures decreases with a higher substitution of Mo. Molybdenum-rich scheelite (up to 2.1 wt%) is characterized by relatively high contents of Nb and Ta (up to 156 and 0.9 ppm, respectively), positive Eu anomalies, high-δ18O values (5.2 to 5.9‰), and relatively low-87Sr/86Sr values (0.70661 to 0.70727), and has grown in a system with a continuous supply of magmatic fluid. Molybdenum-poor scheelite (0.2 wt%) has low contents of Nb and Ta, negative Eu anomalies, low-δ18O values (4.2 to 4.3‰), and relatively high-87Sr/86Sr ratios (0.70748 to 0.70804). This type of scheelite formed in a system with a restricted flow of magmatic fluid during scheelite precipitation became increasingly depleted in elements that substitute into scheelite. The continued reaction of the magmatic fluid with the wall rocks and the precipitation of minerals from the fluid resulted in a systematic change of the δ18O and 87Sr/86Sr ratios. Chemical and isotopic variations in scheelite may reflect the pulsed flow of a magmatic fluid and do not require the involvement of different fluids or contrasting redox conditions.

Language: English

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CRM-geothermal - Gas chemical measurements at the Tuzla, Seferihisar and Dikili geothermal fields, Turkey (2024)

Zimmer, M. ; Strauch, B. ; Niedermann, S. ; [et al.]

GFZ Data Services

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Publication Date: 2024-05-27

Description: To enhance the EU's economic autonomy, feasible options for local sourcing of critical raw materials that would allow for shorter supply routes along with ethical and responsible value chains are under contemplation. Social acceptance of mining in Europe is, however, low, and the establishment of new mining sites faces strong public opposition. Therefore, innovative solutions for the production of primary raw materials need to be developed. A new idea for raw material extraction is the extraction of essential elements from geothermal fluids. Deep geothermal fluids, increasingly used for energy production, often contain high concen-trations of dissolved ions and gases in commercially interesting concentrations. The EU-funded project CRM-geothermal aims to develop new technologies to extract these highly relevant elements, including helium, during geothermal production cycles. In this way, an environmentally friendly and socially acceptable exploration and exploitation method could be deployed. One aim of the CRM-geothermal project is to gain an overview of the actual quantities of critical raw materials in various geothermal fluids in Europe by taking and analyzing fluid samples. In Turkey for instance, classical high enthalpy (volcanic) systems exist, which are representative for many geothermal areas worldwide. The sites are located at the edges of tectonic plates and close to areas undergoing volcanic activity. The brines are mixed with seawater and circulate in the deeper crust. The data publication contains analyses results of three gas samples from Tuzla, two samples from Seferihisar geothermal power plant and one sample from the Dikili geothermal field in Turkey, taken in 2023 as part of the CRM-geothermal project.

Language: English

Type: info:eu-repo/semantics/workingPaper

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