scholarly journals Reply to Norini and Groppelli's comment on “Estimating the depth and evolution of intrusions at resurgent calderas: Los Humeros (Mexico)” by Urbani et al. (2020)

Solid Earth ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 1111-1124
Author(s):  
Stefano Urbani ◽  
Guido Giordano ◽  
Federico Lucci ◽  
Federico Rossetti ◽  
Gerardo Carrasco-Núñez
Keyword(s):  
Dynamic Environment ◽  
Tectonic Deformation ◽  
Structural Studies ◽  
Geothermal Systems ◽  
Secondary Porosity ◽  
Geothermal Exploration ◽  
Deformation Structures ◽  
Transient Rheology ◽  
History Of ◽  
Volcanic Pile

Abstract. Structural studies in active caldera systems are widely used in geothermal exploration to reconstruct volcanological conceptual models. Active calderas are difficult settings to perform such studies mostly because of the highly dynamic environment, dominated by fast accumulation of primary and secondary volcanic deposits, the variable and transient rheology of the shallow volcanic pile, and the continuous feedbacks between faulting, secondary porosity creation, and geothermal fluid circulation, alteration and cementation that tend to obliterate the tectonic deformation structures. In addition, deformation structures can be also caused by near- and far-field stress regimes, which include magmatic intrusions at various depths, the evolving topography and regional tectonics. A lack of consideration of all these factors may severely underpin the reliability of structural studies. By rebutting and providing a detailed discussion of all the points raised by the comment of Norini and Groppelli (2020) to the Urbani et al. (2020) paper, we take the opportunity to specify the scientific rationale of our structural fieldwork and strengthen its relevance for geothermal exploration and exploitation in active caldera geothermal systems in general and, particularly, for the Holocene history of deformation and geothermal circulation in the Los Humeros caldera. At the same time, we identify several major flaws in the approach and results presented in Norini and Groppelli (2020), such as (1) the lack of an appropriate ranking of the deformation structures considering an inventory method for structural analysis; (2) the misinterpretation and misquoting of Urbani et al. (2020) and other relevant scientific literature; and (3) irrelevant and contradictory statements within their comment.

scholarly journals Structural studies in active caldera geothermal systems. Reply to Comment on Estimating the depth and evolution of intrusions at resurgent calderas: Los Humeros (Mexico) by Norini and Groppelli (2020)

2021 ◽  
Author(s):  
Stefano Urbani ◽  
Guido Giordano ◽  
Federico Lucci ◽  
Federico Rossetti ◽  
Valerio Acocella ◽  
...  
Keyword(s):  
Dynamic Environment ◽  
Tectonic Deformation ◽  
Structural Studies ◽  
Geothermal Systems ◽  
Geothermal Exploration ◽  
Deformation Structures ◽  
Transient Rheology ◽  
History Of ◽  
Continuous Feedback ◽  
Volcanic Pile

Abstract. Structural studies in active caldera systems are widely used in geothermal exploration to reconstruct volcanological conceptual models. Active calderas are difficult settings to perform such studies mostly because of the highly dynamic environment, dominated by fast accumulation of primary and secondary volcanic deposits, the variable and transient rheology of the shallow volcanic pile, and the continuous feedback between faulting and geothermal fluid circulation/alteration that tend to obliterate the tectonic deformation structures. In addition, deformation structures can be also caused by near- and far-field stress regimes, which include magmatic intrusions at various depths (volumes and rates), the evolving topography and regional tectonics. A lack of consideration of all these factors may severely underpin the reliability of structural studies. By rebutting and providing a detailed discussion of all the points raised by the comment of Norini and Groppelli (2020) to the Urbani et al. (2020) paper, we take the opportunity to specify the scientific rationale of our structural fieldwork and strengthen its relevance for geothermal exploration/exploitation in active caldera geothermal systems in general, and, particularly, for the Holocene history of deformation and geothermal circulation in the Los Humeros caldera. At the same time, we identify several major flaws in the approach and results presented in Norini and Groppelli (2020).

scholarly journals The complete mitochondrial genome of the intertidal spider (Desis jiaxiangi) provides novel insights into the adaptive evolution of the mitogenome and the evolution of spiders

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Fan Li ◽  
Yunyun Lv ◽  
Zhengyong Wen ◽  
Chao Bian ◽  
Xinhui Zhang ◽  
...  
Keyword(s):  
Positive Selection ◽  
Adaptive Evolution ◽  
Physiological Activity ◽  
Complete Mitochondrial Genome ◽  
Dynamic Environment ◽  
Data Set ◽  
History Of ◽  
Complete Mitogenome ◽  
Selection Signal ◽  
Positive Selection Signal

Abstract Background Although almost all extant spider species live in terrestrial environments, a few species live fully submerged in freshwater or seawater. The intertidal spiders (genus Desis) built silk nests within coral crevices can survive submerged in high tides. The diving bell spider, Argyroneta aquatica, resides in a similar dynamic environment but exclusively in freshwater. Given the pivotal role played by mitochondria in supplying most energy for physiological activity via oxidative phosphorylation and the environment, herein we sequenced the complete mitogenome of Desis jiaxiangi to investigate the adaptive evolution of the aquatic spider mitogenomes and the evolution of spiders. Results We assembled a complete mitogenome of the intertidal spider Desis jiaxiangi and performed comparative mitochondrial analyses of data set comprising of Desis jiaxiangi and other 45 previously published spider mitogenome sequences, including that of Argyroneta aquatica. We found a unique transposition of trnL2 and trnN genes in Desis jiaxiangi. Our robust phylogenetic topology clearly deciphered the evolutionary relationships between Desis jiaxiangi and Argyroneta aquatica as well as other spiders. We dated the divergence of Desis jiaxiangi and Argyroneta aquatica to the late Cretaceous at ~ 98 Ma. Our selection analyses detected a positive selection signal in the nd4 gene of the aquatic branch comprising both Desis jiaxiangi and Argyroneta aquatica. Surprisingly, Pirata subpiraticus, Hypochilus thorelli, and Argyroneta aquatica each had a higher Ka/Ks value in the 13 PCGs dataset among 46 taxa with complete mitogenomes, and these three species also showed positive selection signal in the nd6 gene. Conclusions Our finding of the unique transposition of trnL2 and trnN genes indicates that these genes may have experienced rearrangements in the history of intertidal spider evolution. The positive selection signals in the nd4 and nd6 genes might enable a better understanding of the spider metabolic adaptations in relation to different environments. Our construction of a novel mitogenome for the intertidal spider thus sheds light on the evolutionary history of spiders and their mitogenomes.

Crystallisation of fine- and coarse-grained A-type granite sheets of the Southern Oklahoma Aulacogen, U.S.A.

2000 ◽  
Vol 91 (1-2) ◽  
pp. 139-150 ◽  
Author(s):  
John P. Hogan ◽  
M. Charles Gilbert ◽  
Jon D. Price
Keyword(s):  
Solidus Temperature ◽  
Direct Consequence ◽  
Progressive Increase ◽  
Coarse Grained ◽  
Fine Grained ◽  
Mafic Complex ◽  
Southern Oklahoma ◽  
History Of ◽  
Volcanic Pile ◽  
Crustal Magma

A-type felsic magmatism associated with the Cambrian Southern Oklahoma Aulacogen began with eruption of voluminous rhyolite to form a thick volcanic carapace on top of an eroded layered mafic complex. This angular unconformity became a crustal magma trap and was the locus for emplacement of later subvolcanic plutons. Rising felsic magma batches ponding along this crustal magma trap crystallised first as fine-grained granite sheets and then subsequently as coarser-grained granite sheets. Aplite dykes, pegmatite dykes and porphyries are common within the younger coarser-grained granite sheets but rare to absent within the older fine-grained granite sheets. The older fine-grained granite sheets typically contain abundant granophyre.The differences between fine-grained and coarse-grained granite sheets can largely be attributed to a progressive increase in the depth of the crustal magma trap as the aulacogen evolved. At low pressures (<200MPa) a small increase in the depth of emplacement results in a dramatic increase in the solubility of H2O in felsic magmas. This is a direct consequence of the shape of the H2O-saturated granite solidus. The effect of this slight increase in total pressure on the crystallisation of felsic magmas is to delay vapour saturation, increase the H2O content of the residual melt fractions and further depress the solidus temperature. Higher melt H2O contents, and an extended temperature range over which crystallisation can proceed, both favour crystallisation of coarser-grained granites. In addition, the potential for the development of late, H2O-rich, melt fractions is significantly enhanced. Upon reaching vapour saturation, these late melt fractions are likely to form porphyries, aplite dykes and pegmatite dykes.For the Southern Oklahoma Aulacogen, the progressive increase in the depth of the crustal magma trap at the base of the volcanic pile appears to reflect thickening of the volcanic pile during rifting, but may also reflect emplacement of earlier granite sheets. Thus, the change in textural characteristics of granite sheets of the Wichita Granite Group may hold considerable promise as an avenue for further investigation in interpreting the history of this rifting event.

scholarly journals Anatomy of the magmatic plumbing system of Los Humeros Caldera (Mexico): implications for geothermal systems

2019 ◽  
Author(s):  
Federico Lucci ◽  
Gerardo Carrasco-Núñez ◽  
Federico Rossetti ◽  
Thomas Theye ◽  
John C. White ◽  
...  
Keyword(s):  
Volcanic Belt ◽  
Mineral Chemistry ◽  
Volcanic Complex ◽  
Geothermal Systems ◽  
Plumbing System ◽  
Geothermal Exploration ◽  
Geothermal Fields ◽  
Mexican Volcanic Belt ◽  
Plumbing Systems ◽  
Magmatic Plumbing System

Abstract. Understanding the anatomy of magma plumbing systems of active volcanoes is essential not only for unraveling magma dynamics and eruptive behaviors, but also to define the geometry, depth and temperature of the heat sources for geothermal exploration. The Pleistocene-Holocene Los Humeros volcanic complex is part of the Eastern Trans-Mexican Volcanic Belt (Central Mexico) and it represents one of the most important exploited geothermal fields in Mexico with ca. 90 MW of produced electricity. A field-based petrologic and thermobarometric study of lavas erupted during the Holocene (post-Caldera stage) has been performed with the aim to decipher the anatomy of the magmatic plumbing system existing beneath the caldera. New petrographical, whole rock major element data and mineral chemistry were integrated within a suite of inverse thermobarometric models. Compared with previous studies where a single voluminous melt-controlled magma chamber (or "Standard Model") at shallow depths was proposed, our results support a more complex and realistic scenario characterized by a heterogeneous multilayered system comprising a deep (ca. 30 km) basaltic reservoir feeding progressively shallower and smaller distinct stagnation layers, pockets and batches up to very shallow conditions (1 kbar, ca. 3 km). Evolution of melts in the feeding system is mainly controlled by differentiation processes via fractional crystallization, as recorded by polybaric crystallization of clinopyroxenes and orthopyroxenes. Moreover, this study attempts to emphasize the importance to integrate field-petrography, texture observations and mineral chemistry of primary minerals to unravel the pre-eruptive dynamics and therefore the anatomy of the plumbing system beneath an active volcanic complex, which notwithstanding the numerous existing works is still far to be well understood. A better knowledge of the heat source feeding geothermal systems is very important to improve geothermal exploration strategies.

Zircon Microstructures Record Deformation History of Shock- and Tectonically-generated Pseudotachylites: a Case Study from the Vredefort Impact Structure, South Africa

2019 ◽  
Vol 60 (12) ◽  
pp. 2529-2546 ◽  
Author(s):  
E Kovaleva ◽  
M S Huber ◽  
G Habler ◽  
D A Zamyatin
Keyword(s):  
Tectonic Deformation ◽  
Impact Structure ◽  
Deformation Bands ◽  
Deformation History ◽  
Meteorite Impacts ◽  
History Of ◽  
Tectonic Settings ◽  
New Criterion

Abstract High-strain rate deformation can cause in situ melting of rocks, resulting in the formation of dark, micro- to nanocrystalline pseudotachylite veins. On Earth, pseudotachylite veins form during meteorite impacts, large landslides, and earthquakes. Within the Vredefort impact structure, both impact-generated and (pre-impact) tectonically-generated pseudotachylite veins have been described, but are challenging to distinguish. Here, we demonstrate a genetic distinction between two pseudotachylite veins from Vredefort by studying their petrography, degree of recrystallization and deformation, cross-cutting relationships and the deformation microstructures in associated zircon. We conclude that Vein 1 is pre-impact and tectonically-generated, and Vein 2 is impact-generated. In agreement, zircon microstructures in Vein 1 contain planar deformation bands (PDBs), attributed to tectonic deformation, whereas zircon microstructures in Vein 2 reveal microtwin lamellae, indisputable evidence of shock metamorphism. Thus, deformation microstructures in zircon may provide a new criterion for distinguishing the genetic origin of pseudotachylite veins. Zircons that have been removed from their context (i.e., alluvial or detrital zircon, zircon from Lunar breccia) should be interpreted with caution in terms of their deformation history. For example, zircon with PDBs cannot reliably be used as a marker for shock deformation, because this feature has been shown to form in purely tectonic settings.

A seismotectonic study and minimum 1D velocity model for the Greater Geneva Basin, Western Switzerland

2020 ◽  
Author(s):  
Verónica Antunes ◽  
Thomas Planès ◽  
Jiří Zahradník ◽  
Anne Obermann ◽  
Celso Alvizuri ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Large Scale ◽  
Detection Threshold ◽  
Velocity Model ◽  
Strike Slip ◽  
Tectonic Deformation ◽  
Geothermal Exploration ◽  
Area Of Interest ◽  
The Impact ◽  
1D Velocity Model

&lt;p&gt;In the framework of the Geothermie2020 project, the canton of Geneva and the Industrial Services of Geneva (SIG) are currently developing geothermal exploration in the Greater Geneva Basin (GGB), located in south-western Switzerland and neighbouring France. Before geothermal exploration begins, it is important to investigate the ongoing seismic activity, its relationship with local tectonic features, and the large-scale kinematics of the area. Background seismicity suggest that the local tectonic structures affecting the basin may still be active. Moderate-magnitude earthquakes have been identified along the Vuache fault, a major strike-slip structure crossing the basin. In this context we deployed a dense temporary network of 20 broadband stations around and within the GGB, during ~1.5 years, and reaching a detection threshold 0.5M&lt;sub&gt;L&lt;/sub&gt;.&amp;#160;&lt;/p&gt;&lt;p&gt;Using a new coherence-based detector (LASSIE), we detected and located 158 events in our area of interest. However, only 20 events were located in the GGB, with local magnitudes ranging from 0.7 to 2.2M&lt;sub&gt;L&lt;/sub&gt;. We found no earthquakes in the Canton of Geneva where geothermal activities are taking place. We constructed a local minimum 1D velocity model with VELEST, using the recorded seismicity together with earthquakes from adjacent regions, in a total of 1263 P- and S-picks. The new velocity model allowed to relocate micro-seismic activity up to 11km depth along the main fault systems (i.e. Vuache, Cruseilles, Le Coin, and Arve) offsetting the GGB. We retrieved 8 new focal mechanisms for the area, using a combination of polarities and waveform inversion techniques (CSPS method). A stress inversion shows a tectonic deformation dominated by a quasi-pure strike-slip regime in the GGB, consistent with structural and geological data.&lt;/p&gt;&lt;p&gt;The study of microseismicity in a quiet sedimentary basin is challenging due to the scarce occurrence of seismic events combined with low signal-to-noise ratios and the often strong attenuation. However, the investigation of the sporadic (yet present) natural seismicity with dedicated dense networks could provide useful information about the GGB, even with a short-term experiment. We propose a newly-computed 1D velocity model that can be used in the GGB for seismic monitoring purposes throughout the geothermal project. This model can be easily improved later on, whenever more data is available. Monitoring the evolution and dispersion of the seismic-activity through the identified seismogenic areas during the geothermal project is essential. Quantifying the seismic rate in the basin before geothermal operations start will help to quantify the impact that geothermal energy extraction might have on the GGB.&amp;#160;&lt;/p&gt;

History of tectonic deformation in the interior plains of the Caloris basin, mercury

2011 ◽  
Vol 45 (6) ◽  
pp. 471-497 ◽  
Author(s):  
A. T. Basilevsky ◽  
J. W. Head ◽  
C. I. Fassett ◽  
G. Michael
Keyword(s):  
Tectonic Deformation ◽  
History Of ◽  
Caloris Basin

scholarly journals Hydrochemistry in Geothermal Investigations in Iceland Techniques and Applications

1979 ◽  
Vol 10 (2-3) ◽  
pp. 191-224 ◽  
Author(s):  
Stefán Arnórsson
Keyword(s):  
Water Movement ◽  
Areal Extent ◽  
Geothermal Systems ◽  
Environmental Aspects ◽  
Mixing Processes ◽  
Geothermal Exploration ◽  
Flow Mixing ◽  
Surface Exploration ◽  
Exploration Phase

The role of hydrochemistry in geothermal exploration and development is described. During the surface exploration phase hydrochemistry is particularly useful in delineating regional ground-water movement, in estimating underground temperatures, and in mapping the areal extent of geothermal systems. From data obtained through exploratory and investigation, drilling hydrochemistry yields information on the direction of underground geothermal water flow, mixing processes, boiling in the aquifer, and distribution of underground temperatures. It also contributes significantly in defining and solving scaling and corrosion problems and is relevant for environmental aspects of fluid disposal and constructional design.

scholarly journals Deformation structures in central Nepal and their engineering geological significance

1998 ◽  
Vol 18 ◽  
Author(s):  
Indra Raj Humagain ◽  
K. Schetelig ◽  
M. P. Sharma ◽  
B. N. Upreti ◽  
M. Langer
Keyword(s):  
Cross Sections ◽  
Decisive Role ◽  
Tectonic Deformation ◽  
Deformation Structures ◽  
Central Nepal ◽  
Discontinuous Deformation ◽  
The Stability ◽  
Air Photo ◽  
Cut Slopes ◽  
Different Order

Geological maps of the Helambu-Kathmandu area and Kathmandu-Hetauda area with their suitable cross-sections are presented. On the basis of the deformation history, the deformation structures recorded from the field study as well as from the air photo interpretations are classified as continuous and discontinuous deformation structures. All types of discontinuous deformation structures are considered as discontinuities. Discontinuities play decisive role in engineering geology breaking the continuity of the mechanical behaviour of the rockmass at different scales. On the basis of spacing, width, mineral fill and extent, the discontinuities are classified into seven orders. Such classification is essential and appropriate for rockmasses, which are heavily affected by intense tectonic deformation in the Himalaya, the Alps or corresponding orogens. The study area within central Nepal is having many engineering geological problems. Stability of the rock slopes and underground excavations are two major engineering geological problems to deal here with. Significance of the different order of discontinuities in the light of these engineering geological problems are discussed. Orientation of different order of discontinuities is an important parameter affecting blasting, span width, roof support and ground water flow and related problems in the proposed tunnels in the study area. Such structures are also important factor for the stability of the natural slopes and cut slopes.

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