Hydrothermal fluids circulation and travertine deposition in an active tectonic setting: Insights from the Kamara geothermal area (western Anatolia, Turkey)

2016 ◽  
Vol 680 ◽  
pp. 211-232 ◽  
Author(s):  
Andrea Brogi ◽  
M. Cihat Alçiçek ◽  
Cahit Çağlar Yalçıner ◽  
Enrico Capezzuoli ◽  
Domenico Liotta ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Hydrothermal Fluids ◽  
Western Anatolia ◽  
Geothermal Area ◽  
Active Tectonic ◽  
Travertine Deposition

scholarly journals Fissure Ridges: A Reappraisal of Faulting and Travertine Deposition (Travitonics)

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 278
Author(s):  
Andrea Brogi ◽  
Enrico Capezzuoli ◽  
Volkan Karabacak ◽  
Mehmet Cihat Alcicek ◽  
Lianchao Luo
Keyword(s):  
State Of The Art ◽  
Tectonic Setting ◽  
Original Data ◽  
Apical Part ◽  
Thermal Waters ◽  
Growth Mechanisms ◽  
Depositional Facies ◽  
Geothermal Fluids ◽  
Tectonic Features ◽  
Travertine Deposition

The mechanical discontinuities in the upper crust (i.e., faults and related fractures) lead to the uprising of geothermal fluids to the Earth’s surface. If fluids are enriched in Ca2+ and HCO3-, masses of CaCO3 (i.e., travertine deposits) can form mainly due to the CO2 leakage from the thermal waters. Among other things, fissure-ridge-type deposits are peculiar travertine bodies made of bedded carbonate that gently to steeply dip away from the apical part where a central fissure is located, corresponding to the fracture trace intersecting the substratum; these morpho-tectonic features are the most useful deposits for tectonic and paleoseismological investigation, as their development is contemporaneous with the activity of faults leading to the enhancement of permeability that serves to guarantee the circulation of fluids and their emergence. Therefore, the fissure ridge architecture sheds light on the interplay among fault activity, travertine deposition, and ridge evolution, providing key geo-chronologic constraints due to the fact that travertine can be dated by different radiometric methods. In recent years, studies dealing with travertine fissure ridges have been considerably improved to provide a large amount of information. In this paper, we report the state of the art of knowledge on this topic refining the literature data as well as adding original data, mainly focusing on the fissure ridge morphology, internal architecture, depositional facies, growth mechanisms, tectonic setting in which the fissure ridges develop, and advantages of using the fissure ridges for neotectonic and seismotectonic studies.

scholarly journals Full-Waveform based methods for Microseismic Monitoring Operations: an Application to Natural and Induced Seismicity in the Hengill Geothermal Area, Iceland

2020 ◽  
Vol 54 ◽  
pp. 129-136
Author(s):  
Camilla Rossi ◽  
Francesco Grigoli ◽  
Simone Cesca ◽  
Sebastian Heimann ◽  
Paolo Gasperini ◽  
...  
Keyword(s):  
Power Plants ◽  
Tectonic Setting ◽  
Electrical Power ◽  
Monitoring Network ◽  
Microseismic Monitoring ◽  
Volcanic Area ◽  
Seismic Zone ◽  
Geothermal Area ◽  
Geothermal Systems ◽  
Full Waveform

Abstract. Geothermal systems in the Hengill volcanic area, SW Iceland, started to be exploited for electrical power and heat production since the late 1960s. Today the two largest operating geothermal power plants are located at Nesjavellir and Hellisheiði. This area is a complex tectonic and geothermal site, located at the triple junction between the Reykjanes Peninsula (RP), the Western Volcanic Zone (WVZ), and the South Iceland Seismic Zone (SISZ). The region is seismically highly active with several thousand earthquakes located yearly. The origin of such earthquakes may be either natural or anthropogenic. The analysis of microseismicity can provide useful information on natural active processes in tectonic, geothermal and volcanic environments as well as on physical mechanisms governing induced events. Here, we investigate the microseismicity occurring in Hengill area, using a very dense broadband seismic monitoring network deployed in Hellisheiði since November 2018, and apply sophisticated full-waveform based method for detection and location. Improved locations and first characterization indicate that it is possible to identify different types of microseismic clusters, which are associated with either production/injection or the tectonic setting of the geothermal area.

scholarly journals Weathering of Ophiolite Remnant and Formation of Ni Laterite in a Strong Uplifted Tectonic Region (Yuanjiang, Southwest China)

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 51 ◽  
Author(s):  
Wei Fu ◽  
Yangyang Feng ◽  
Peng Luo ◽  
Yinmeng Zhang ◽  
Xiaorong Huang ◽  
...  
Keyword(s):  
Southwest China ◽  
Tectonic Setting ◽  
Continuous Operation ◽  
Tectonic Uplift ◽  
Yunnan Plateau ◽  
Active Tectonic ◽  
History Of ◽  
Southwestern Margin ◽  
Planation Surfaces ◽  
Weathering Process

The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest Ni producer in China following the Jinchuan super-large magmatic Ni–Cu deposit. This Ni deposit is hosted within the lateritic regolith derived from serpentinite within the regional Paleo-Tethyan Ophiolite remnants. Local landscape controls the distribution of the Ni mineralized regolith, and spatially it is characterized by developing on several stepped planation surfaces. Three types of lateritic Ni ores are identified based on Ni-hosting minerals, namely oxide ore, oxide-silicate mixed ore and silicate ore. In the dominant silicate ore, two phyllosilicate minerals (serpentine and talc) are the Ni-host minerals. Their Ni compositions, however, are remarkably different. Serpentine (0.34–1.2 wt % Ni) has a higher Ni concentration than talc (0.18–0.26 wt % Ni), indicating that the serpentine is more significantly enriched in Ni during weathering process compared to talc. This explains why talc veining reduces Ni grade. The geochemical index (S/SAF value = 0.33–0.81, UMIA values = 17–60) indicates that the serpentinite-derived regolith has experienced, at least, weak to moderate lateritization. Based on several lines of paleoclimate evidence, the history of lateritization at Yuanjiang area probably dates to the Oligocene-Miocene boundary and has extended to the present. With a hydrology-controlled lateritization process ongoing, continuous operation of Ni migration from the serpentinite-forming minerals to weathered minerals (goethite and serpentine) gave rise to the development of three types of Ni ore in the regolith. Notably, the formation and preservation of the Yuanjiang lateritic Ni deposit has been strongly impacted by regional multi-staged tectonic uplift during the development of Yunnan Plateau. This active tectonic setting has promoted weathering of serpentinite and supergene Ni enrichment, but is also responsible for its partial erosion.

Very coarse-grained beaches as a response to generalized sea level drops in a complex active tectonic setting: Pleistocene marine terraces at the Cadiz coast, SW Spain

2016 ◽  
Vol 382 ◽  
pp. 92-110 ◽  
Author(s):  
Laura González-Acebrón ◽  
Ramón Mas ◽  
José Arribas ◽  
Jose Manuel Gutiérrez-Mas ◽  
Carlos Pérez-Garrido
Keyword(s):  
Sea Level ◽  
Tectonic Setting ◽  
Coarse Grained ◽  
Sw Spain ◽  
Marine Terraces ◽  
Active Tectonic

Unusual Mw 7.0 Extensional Aegean Earthquake Related to African Slab Rollback and Formation of Extensional Plate Boundary in Anatolia 

2021 ◽  
Author(s):  
Jiannan Meng ◽  
Ozan Sinoplu ◽  
Zhipeng Zhou ◽  
Bulent Tokay ◽  
Timothy Kusky ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Plate Boundary ◽  
Volcanic Eruptions ◽  
Western Anatolia ◽  
Rift System ◽  
African Plate ◽  
Tectonic Processes ◽  
Slab Rollback ◽  
Earthquake Frequency ◽  
Pure Extension

<p><strong>A devastating M 7.0 earthquake on October 30, 2020, offshore Samos Island, Greece, was a consequence of the Aegean and Anatolian upper crust being pulled apart by north-south extensional stresses resulting from slab rollback, where the African plate is subducting northwards beneath Eurasia, while the slab is sinking by gravitational forces, causing it to retreat southwards. Since the retreating African slab is coupled with the overriding plate, it tears the upper plate apart as it retreats, breaking it into numerous small plates with frequent earthquakes along their boundaries.  The earthquake happened offshore of the extensional B</strong><strong>ü</strong><strong>y</strong><strong>ü</strong><strong>k Menderes Graben, where a 150 km long, 10 km wide, incipient upper plate rift system formed in the Anatolian plate, showing that the entire Aegean-Western Anatolian region is being pulled apart by extensional stresses related to the slab rollback. Earthquake solutions and fault plane studies around western Anatolia support this spectacular extension, and show that the modern extension was preceded on many faults by oblique extension and strike-slip motions, perhaps reflecting a change in tectonic setting from sideways escape from the Africa-Arabia collision with Eurasia,  to the pure extension related to slab rollback of the African plate, and the retreat of the Hellenic trench. Historical earthquake swarms and deformation of the upper plate in the Aegean have been associated with massive volcanism and cataclysmic devastation, such as the M 7.7 Amorgos earthquake in July 1956 between the islands of Naxos and Santorini (Thera). Even more notable was the eruption of Santorini 3650 years ago, which contributed to the fall of the Minoan civilization. The Samos earthquake highlights the long historical lack of appreciation of links between deep tectonic processes and upper crustal deformation and geological hazards, and is a harbinger of future earthquakes and volcanic eruptions, establishing a basis for studies to institute better protection of infrastructure and upper plate cultures in the region.</strong><strong> Further detailed studies are needed in this area to better understand and predict earthquake frequency, possible locations, and to establish better building codes to protect people's lives and property.</strong></p><p><strong><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.9a0ea6af400066213360161/sdaolpUECMynit/12UGE&app=m&a=0&c=672cb3d1887c66c27ef7b2ac01552f9d&ct=x&pn=gepj.elif&d=1" alt=""></strong></p>

How reliable are maximum depositional age estimates based on detrital zircon? An example from Early Palaeozoic successions of the Trondheim Nappe Complex, Scandinavian Caledonides

2021 ◽  
Author(s):  
Deta Gasser ◽  
Tor Grenne ◽  
Bjørgunn Dalslåen ◽  
Trond Slagstad ◽  
David Roberts ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Tectonic Setting ◽  
Maximum Error ◽  
Detrital Zircons ◽  
Greenschist Facies ◽  
Scandinavian Caledonides ◽  
Nappe Complex ◽  
Active Tectonic ◽  
Depositional Age ◽  
Age Estimates

<p>U-Pb age spectra of detrital zircons are widely used to estimate maximum depositional ages (MDA) for sedimentary successions of various age. Different methods have been proposed for calculating an MDA. The most common are based on calculated ages of either the youngest single grain (YSG), the youngest grain cluster composed of three or more grains that overlap at 2σ (YGC 2σ), or the youngest graphical peak (YPP). Many of these methods produce MDAs consistent with biostratigraphic age or the radiometric age of volcanic horizons within the same unit; however, several studies have shown that MDA estimates based on detrital zircon can be younger than the true depositional age, particularly in active tectonic settings, indicating that the methods should be applied with care for successions where independent depositional age control is lacking.</p><p>In this contribution we present a compilation of 27 detrital zircon samples from Ordovician to Silurian strata from a part of the Trondheim Nappe Complex of the central Scandinavian Caledonides. The samples belong to six stratigraphically distinct units with independent age control from fossils, dated volcanic horizons or bracketing units of known age. These successions represent various marginal basins filled during the closing stages of the Iapetus Ocean in an overall active tectonic setting with detritus from both continental landmasses and Cambro-Ordovician island arcs. Shortly after deposition, the successions were folded and metamorphosed at up to greenschist facies during Taconian accretionary events and/or the Scandian continent-continent collision.</p><p>We calculated MDAs by the three methods YSG, YGC 2σ and YPP for all samples based on <sup>206</sup>Pb/<sup> 238</sup>U ages, applying a rigorous discordance filter of 5% (most studies use 10%), in order to use the most reliable analyses possible. Our analysis shows that the YSG MDA is up to 36 m.y. younger than the known depositional age for 17 of the 27 samples, with up to six individual grains giving too young age estimates in some samples. Hence, YSG MDA obviously does not provide a reliable MDA estimate. Of the YGC 2σ (weighted mean age) estimates, six are still significantly younger than known depositional age; and an additional seven are younger but overlap with the known depositional age when considering the maximum error on the YGC 2σ estimate. The only method which provides an MDA estimate within the age of known deposition or older for all samples is the YPP method.</p><p>Our results indicate that statistically robust estimates of MDA from detrital zircon data in such an active orogenic setting are provided only by the YPP method; both the YSG and the YGC 2σ methods provided unreliably young estimates even with a discordance filter of 5% (using a filter of only 10% makes the problem considerably worse). The spuriously young ages of up to six near-concordant grains in some samples is probably due to concealed lead loss, possibly caused by (fluid-assisted?) recrystallisation of zircon domains during regional greenschist-facies metamorphism shortly after deposition.</p>

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