19,132 research outputs found

    Ecological successions throughout the desiccation of Tirez lagoon (Spain) as an astrobiological time-analog for wet-to-dry transitions on Mars

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    Tirez was a small and seasonal endorheic athalassohaline lagoon that was located in central Spain. In recent years, the lagoon has totally dried out, offering for the first time the opportunity to analyze its desiccation process as a “time-analog” to similar events occurred in paleolakes with varying salinity during the wet-to-dry transition on early Mars. On the martian cratered highlands, an early period of water ponding within enclosed basins evolved to a complete desiccation of the lakes, leading to deposition of evaporitic sequences during the Noachian and into the Late Hesperian. As Tirez also underwent a process of desiccation, here we describe (i) the microbial ecology of Tirez when the lagoon was still active 20 years ago, with prokaryotes adapted to extreme saline conditions; (ii) the composition of the microbial community in the dried lake sediments today, in many case groups that thrive in sediments of extreme environments; and (iii) the molecular and isotopic analysis of the lipid biomarkers that can be recovered from the sediments today. We discuss the implications of these results to better understanding the ecology of possible Martian microbial communities during the wet-to-dry transition at the end of the Hesperian, and how they may inform about research strategies to search for possible biomarkers in Mars after all the water was los

    Anatomy and kinematic evolution of an ancient passive margin involved into an orogenic wedge (Western Southern Alps, Varese area, Italy and Switzerland)

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    We make use of own geological mapping, interpretations of seismic reflection profiles and deep geophysical data to build a lithospheric-scale cross-section across the European Western Southern Alps (Varese area) and to model a progressive restoration from the end of Mesozoic rifting to present-day. Early phases of Alpine orogeny were characterized by Europe-directed thrusting, whereas post-Oligocene shortening led to basement-involving crustal accretion accompanied by backfolding, and consistent with the kinematics of the adjoining Ivrea Zone. Wedging was favored by a significant component of reactivation of the inherited Adriatic rifted margin. Our results also suggest that, during the collisional and post-collisional tectonics, lithosphere dynamics drove diachronically the onset of tectonic phases (i.e., wedging and slab retreat), from east to west, across the Western Southern Alps

    Ökumene im Anthropozän

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    Angesichts der globalen Umweltveränderungen, die sich unter dem Stichwort „Anthropozän“ zusammenfassen lassen, muss sich auch die Gesellschaft verändern. Damit dies gelingt, müssten alle gesellschaftlichen Kräfte proaktiv mitwirken. Die vorliegenden transformationstheoretischen Überlegungen konzentrieren sich auf den Beitrag der Kirche. Zunächst wird die neue Konstellation des Anthropozäns unter den beiden zusammenhängenden Aspekten des Anfangs und der Bezeichnung näher konturiert. Es wird herausgearbeitet, dass die Ursachen für die Umweltveränderungen in der spezifische Sozialform der modernen Gesellschaft zu suchen sind, wobei die Analyse gleichzeitig den Schritt vom Globalen zum Planetarischen machen muss. Mit Blick auf die anstehende gesellschaftliche Transformation wird der kulturelle Rahmen über das Merkmal der Expansion näher bestimmt. Auf der Grundlage eines mehrschichtigen Transformationsmodells werden die Potenziale der Kirche, den gesellschaftlichen Wandel positiv mitzugestalten, diskutiert. Abschließend wird unter Rückgriff auf das Bild der Erde als gemeinsames Haus die Wichtigkeit der Arbeit am Weltbild dargelegt.Given the global environmental changes, summarized under the keyword “Anthropocene,” society must also change. For this to succeed, all social forces must participate proactively. The present transformation- theoretical considerations focus on the contribution of the Church. First, it outlines the new constellation of the Anthropocene in more detail under the two interrelated aspects of its beginning and designation. It concludes that the causes of environmental change are situated in the specific social forms of modern society, whereby the analysis must simultaneously shift from the global to the planetary perspective. Considering the upcoming social transformation, the cultural framework is further defined by the characteristic of expansion. Based on a multilayered transformation model, the article discusses the potential of the Church to positively shape social change. Finally, using the image of the Earth as a common house, it highlights the importance of working for the worldview

    Study of GIS-based groundwater potential zones for agricultural sustainability in the arid region

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    The cluster-wise area of shallow and deep aquifer zones is used to estimate the potential of groundwater. The potential of the shallow aquifer zone is estimated at 4.61 MCM (million cubic meters) and for the deep aquifer zone at 17,509.03 MCM, while the total groundwater potential for both aquifer zones is estimated at 17,513.64 MCM. The Geographical Information System (GIS) was employed efficiently to estimate the subsurface volume of the lithological rock layers using cost-effective and time-saving techniques, while the Rockwork software integrated with GIS was successfully used to visualize the subsurface lithology and stratigraphy of the aquifer zones. The estimated potential of groundwater can be uncovered by using the alternative solar pumping system to improve the agricultural system in the study area, thereby reducing the migration rate, reducing poverty, and improving the socio-economic conditions of livelihood. In the future, too, it will be essential to design water quality studies to ensure the proper use of groundwater. HIGHLIGHTS The current study discovered two potential groundwater zones of the (shallow and deep) aquifer.; The potential of the groundwater has been estimated using GIS for future planning and development.; The overall groundwater potential for both aquifer zones is estimated at 17,513.64 MCM.

    Pleniglacial dynamics in an oceanic central European loess landscape

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    Loess–palaeosol sequences (LPSs) of the oceanic-influenced European loess belt underwent frequent post-depositional processes induced by surface runoff or periglacial processes. The interpretation of such atypical LPSs is not straightforward, and they cannot be easily used for regional to continental correlations. Within the last few years, however, such sequences gained increased attention, as they are valuable archives for regional landscape dynamics. In this study, the Siersdorf LPS was analysed using a multi-proxy approach using sedimentological, geochemical, and spectrophotometric methods combined with luminescence dating and tentative malacological tests to unravel Pleniglacial dynamics of the Lower Rhine Embayment. A marshy wetland environment for the late Middle Pleniglacial to the early Upper Pleniglacial was shown by colour reflectance and grain size distribution. Age inversions from luminescence dating paired with geochemical and sedimentological data reveal long-lasting erosional processes during the early Upper Pleniglacial, which were constrained to a relatively small catchment with short transport ranges. The upper sequence shows typical marker horizons for the study area and indicate harsh, cold-arid conditions for the late Upper Pleniglacial. In comparison with other terrestrial archives, the Siersdorf LPS shows that the Lower Rhine Embayment was more diverse than previously assumed, regarding not only its geomorphological settings and related processes but also its ecosystems and environments.</p

    Metallogeny in the Bangong–Nujiang belt, central Tibet, China: A review

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    The Bangong–Nujiang metallogenic belt consists of scattered Tethyan oceanic blocks, mainly distributed underneath the margins of the Qiangtang and Lhasa terranes in central Tibet. A new world-class metallogenic belt has been reported in this region recently, based on the geological mapping and ore deposit prospecting over the last two decades. It currently comprises inferred resources of 30 Mt Cu and 500 t Au, together with several Cr–Ni, Fe, and W (Mo) resources, forming a significant potential area for future mineral exploration. These metals are mainly hosted in porphyry copper, skarn copper, skarn iron, orogenic gold, quartz-vein tungsten, and ophitic chromite deposits. The mineral deposits in the Bangong–Nujiang metallogenic belt have been widely recognized in different localities, including the southern edge of the southern Qiangtang block, part of the north Lhasa block, and even part of the central Lhasa block, indicating they were formed in variable geological settings, from the initial opening, subduction, and collision to the extension of the Bangong–Nujiang Ocean. Specifically, five major tectonic events contributed to mineralization, including the stage 1 (240–165 Ma) initial opening of the Bangong–Nujiang Ocean, stage 2 (165–145 Ma) oceanic subduction, stage 3 (145–100 Ma) close of the ocean, stage 4 (100–65 Ma) continent–continent collisional orogenesis, and stage 5 (65–0 Ma) post-orogenesis. At stage 1, Cr–Ni deposits were formed during the initial opening of the ocean; porphyry–epithermal Cu (Au), skarn Fe, and minor orogenic Au deposits were formed at stage 2 and stage 3; a younger pulse of a few porphyry–skarn Cu ± Mo and orogenic Au deposits were formed during stage 4; finally, W(Mo) deposits were generated in stage 5. In general, porphyry Cu systems, orogenic Au, and skarn Cu polymetallic deposits that occurred in the subduction and post-collision settings related W(Mo) deposits have the most potential for future exploration. An in-depth investigation of several scientific problems, such as addressing the tectonic setting, magmatism, and metallogeny of this region and genetic linkage of these deposit preservations to plateau uplift, is essential for the future success of exploration in the Bangong–Nujiang metallogenic belt

    Constraints on Incremental Assembly of Upper Crustal Igneous Intrusions, Mount Ellen, Henry Mountains, Utah

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    Magma systems within the shallow crust drive volcanic processes at the surface. Studying active magma systems directly poses significant difficulty but details of ancient magma systems can provide insight to modern systems. The ancient intrusions now exposed in the Henry Mountains of southern Utah provide an excellent opportunity to study the emplacement of igneous intrusions within the shallow crust. The five main intrusive centers of the Henry Mountains are Oligocene in age and preserve different stages in the development of an igneous system within the shallow crust. Recent studies worldwide have demonstrated that most substantial (> 0.5 km3) igneous intrusions in the shallow crust are incrementally assembled from multiple magma pulses. In the Henry Mountains, smaller component intrusions (< 0.5 km3) clearly demonstrate incremental assembly but an evaluation of incremental assembly for an entire intrusive center has yet to be performed. The Mount Ellen intrusive complex is the largest intrusive center (~ 100 km3, 15 – 20 km diameter) in the Henry Mountains. This thesis research provides constraints on the construction history and emplacement of Mount Ellen using a combination of multiple techniques, including fieldwork, whole-rock major and trace element geochemistry, anisotropy of magnetic susceptibility, and crystal size distribution analysis. Field work and anisotropy of magnetic susceptibility data suggest that Mount Ellen is a laccolith that in cross section is built a network of stacked igneous sheets. In map-view, the laccolith has an elliptical shape built from numerous igneous lobes radiating away from the central portion of the intrusion. Field observations suggest most lobes are texturally homogenous and likely emplaced from a single magma batch. Samples collected throughout Mount Ellen were divided into five groups based on a qualitative evaluation of texture. Possible distinctions between these textural groups were then tested using several different techniques. Geochemistry, anisotropy of magnetic susceptibility, and phenocryst crystal size distribution data are individually not sufficient to distinguish all five textural groups. However, limited datasets for two textures can be consistently distinguished using these techniques. These new results can be integrated with existing constraints to create a comprehensive model for the construction history of Mount Ellen. The intrusive center was constructed in approximately 1 million years at a time-averaged magma injection rate of 0.0004 km3 y-1. The laccolith geometry was built from a radiating network of stacked igneous sheets. The sheets are lobate in map-view (longer than they are wide) and were fed radially outward from a central feeder zone. These component intrusions were emplaced by a minimum of 5 texturally distinct magma pulses, with periods of little or no magmatism between sequential pulses

    Assessing the Effects of Instream Large Wood on Floodplain Aquifer Recharge and Storage at Indian Creek, Kittitas County, Washington, USA

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    Numerous stream restoration projects in the Yakima River Basin in Washington have placed large wood (LW) into tributary channels. One intended effect is to divert water onto floodplains to increase groundwater (GW) recharge and seasonal storage in shallow alluvial aquifers during spring high flows with the intention of releasing GW into streams during the drier summer months. Large wood was emplaced in the Indian Creek tributary of the Teanaway River in Kittitas County, Washington beginning in 2016. Potential changes in the groundwater recharge in the adjacent floodplain before and after the LW installation were investigated through stratigraphic analysis, stream-flow modeling, and GW levels in six piezometers installed in 2014 and 2018. Stratigraphic descriptions of the stream banks reveal a ubiquitous silt/clay dominant layer (60-90 cm thick) at a depth of 1 meter or less, overlying a sand and gravel layer (15-50 cm thick), a clay/silt layer (~30 cm thick), and another sand and gravel layer. These relatively continuous clay layers extend at least 2.2 km upstream from the mouth of Indian Creek on both sides of the channel. Similar clay units have been mapped in the region as glacial drift or lacustrine deposits. The measured stream flow and GW levels in the monitoring wells before and after the LW emplacement show no detectable effect of the LW on seasonal or longer-term GW levels. Data loggers show that GW levels return to baseflow within days of monthly precipitation exceeding 70 mm, suggesting GW flow within the permeable sand and gravel layers beneath or between the clay/silt layers. Available data show that the highest spring GW elevations precede peak stream discharge, indicating that the peak streamflow is not a significant source of GW recharge. A 1-dimensional hydraulic model run with and without channel obstructions at spring monthly average discharge and peak discharge suggests that the water surface elevation may increase ~10-50 cm within and upstream of LW. This assessment of stratigraphy coupled with GW data and stream-flow model can provide insight into the effectiveness of GW recharge from LW restoration projects in similar settings within the region
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