scholarly journals Evidence of Tectonic Control on the Geochemical Features of the Volatiles Vented along the Nebrodi-Peloritani Mts (Southern Apennine Chain, Italy)

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Francesco Italiano ◽  
Pietro Bonfanti ◽  
Salvatore Roberto Maugeri
Keyword(s):  
Continuous Monitoring ◽  
Isotopic Ratio ◽  
Accumulation Rate ◽  
Tectonic Setting ◽  
Metamorphic Rocks ◽  
Fault Rupture ◽  
Mantle Helium ◽  
Locked Fault ◽  
Insight Into ◽  
Apennine Chain

Investigations carried out over the southernmost portion of the Apennine chain (Nebrodi-Peloritani Mountains, Sicily, Italy) reveal a close connection between the tectonic setting and the regional degassing of CO2-dominated volatiles. The geochemical features of the collected gases show that the pristine composition has been modified by gas-water interaction (GWI) and degassing processes. The 3He/4He isotopic ratio in the range of 0.7-2.8 Ra highlights variable contributions of mantle-derived helium, representing an unusual feature for the crustal regime of the study areas characterized by the widespread presence of 4He-producer metamorphic rocks. The degassing of mantle helium is coherent with the tectonics and related to the NW-SE extensional regime of the Calabro-Peloritan Arc (CPA). We propose that the degassing regime as well as the geochemical features of both the dissolved and bubbling gases is closely connected to the strain accumulation rate, inducing almost no temporal changes and insignificant deep-originated fluid contributions to the locked fault volumes. Investigations including discrete and continuous monitoring and degassing-rate estimations are useful tools to gain a better insight into the evolution of seismogenesis, considering the fault rupture as the final stage of a seismic cycle.

scholarly journals Leaf and root pectin methylesterase activity and 13C/12C stable isotopic ratio measurements of methanol emissions give insight into methanol production in Lycopersicon esculentum

2011 ◽  
Vol 191 (4) ◽  
pp. 1031-1040 ◽  
Author(s):  
Patricia Yoshino Oikawa ◽  
Brian M. Giebel ◽  
Leonel da Silveira Lobo O’Reilly Sternberg ◽  
Lei Li ◽  
Michael P. Timko ◽  
...  
Keyword(s):  
Lycopersicon Esculentum ◽  
Isotopic Ratio ◽  
Pectin Methylesterase ◽  
Methanol Production ◽  
Stable Isotopic ◽  
Stable Isotopic Ratio ◽  
Insight Into

The uplift of high-pressure-low-temperature metamorphic rocks

1987 ◽  
Vol 321 (1557) ◽  
pp. 87-103 ◽  
Keyword(s):  
Tectonic Setting ◽  
Geothermal Gradient ◽  
Dominant Mode ◽  
Metamorphic Rocks ◽  
Return Flow ◽  
Accretionary Wedge ◽  
Moderate Amount ◽  
Low Viscosity ◽  
Buoyancy Forces ◽  
Flowing Material

The uplift of high- P -low- T metamorphic rocks has been attributed to buoyancy, diapirism, or hydrodynamically driven return flow. Buoyancy forces can return material subducted into the mantle only if subduction slows or ceases, reducing the downward traction. The buoyancy forces will be reversed within the crust, because of the increased density of high- P assemblages, and therefore can not cause the subducted material to rise beyond the base of the crust. Diapirism and hydrodynamic flow processes require a low-density, low-viscosity matrix, and can only explain the emplacement of relatively small bodies of high- P rock entrained in the flowing material. The tectonic setting of coherent regional high- P —low- T terrains can be explained in terms of the mechanical behaviour of an accretionary wedge with negligible yield strength, where underplating is the dominant mode of accretion. Underplating thickens the wedge from beneath and increases its surface slope. This causes the upper part of the wedge to extend horizontally, even though convergence is continuing. Continued underplating beneath and extension above can allow the oldest high- P rocks to rise to within reach of a moderate amount of erosion on a time scale of the order of 10 Ma. As long as subduction continues beneath the wedge, the geothermal gradient will not relax to a normal value. This process explains (a) the evidence that high- P -low- T rocks are commonly uplifted while convergence is continuing; (b) the absence in many cases of significant overprinting by higher- T assemblages; (c) the position of the oldest and highest pressure rocks in the upper rear of orogenic wedges; (d) the lack of adequate tectonic thicknesses of overlying rock to explain the metamorphism; and (e) the common occurrence of post-metamorphic faults that excise parts of the metamorphic zonation.

Diamond from the Dabie Shan Metamorphic Rocks and Its Implication for Tectonic Setting

Science ◽  
1992 ◽  
Vol 256 (5053) ◽  
pp. 80-82 ◽  
Author(s):  
X. Shutong ◽  
S. Wen ◽  
L. Yican ◽  
J. Laili ◽  
J. Shouyuan ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Metamorphic Rocks ◽  
Dabie Shan

scholarly journals The observed thermal anomaly as an earthquake Precursor: A case study from the 1993 Latur earthquake prone area in Western India

2021 ◽  
Author(s):  
Vijay P Dimri ◽  
Simanchal Padhy ◽  
N C Mondal ◽  
G K Reddy ◽  
G G. Ramacharyulu ◽  
...  
Keyword(s):  
Continuous Monitoring ◽  
Seismic Hazard Assessment ◽  
Thermal Anomaly ◽  
Atmospheric Temperature ◽  
Research Area ◽  
Earthquake Precursor ◽  
Western India ◽  
Monsoon Period ◽  
Prone Area ◽  
Insight Into

Abstract We report and discuss monitoring of short-term variations of widely used multi-geophysical parameters in Latur-Killari area in western India, the region that witnessed a major devastating earthquake in 1993. An abnormal rise in atmospheric temperature of more than 20°C at 11200 m height was observed in the air-flight just 100 km away from Latur during a monsoon period. We investigated the cause of such abnormal rise in temperature in relation to the seismicity of the area for the 1993 Latur earthquake along with the continuous monitoring of ground water level and soil Helium gas for a week under a precursory 'quick please' operation in the study area. There were no seismic signals associated with this precursor rise that led to the suspension of the operation after a week time. It is also observed that this thermal anomaly is not followed by any major earthquake over the area, which has larger implications in atmosphere research area, suggesting a detailed investigation of such anomaly that may provide a better insight into the precursory behavior of the observed thermal anomaly by overcoming the constraints of accurate retrieval of temperature due to inadequate penetration of Satellite based thermal sensor into thick clouds. Findings of this study certainly call for continuous monitoring of temperature over the earthquake prone areas to gain insight into the physics of short-lived variation in temperature over spatially limited extent, especially over the earthquake prone areas for improved seismic hazard assessment.

scholarly journals Zircon U–Pb geochronology and geochemistry of granitic rocks in central Mongolia

2020 ◽  
Vol 50 ◽  
pp. 23-44
Author(s):  
Boldbaatar Dolzodmaa ◽  
Yasuhito Osanai ◽  
Nobuhiko Nakano ◽  
Tatsuro Adachi
Keyword(s):  
Tectonic Setting ◽  
Granitic Rocks ◽  
Metamorphic Rocks ◽  
Calc Alkaline ◽  
Volcanic Arc ◽  
Central Mongolia ◽  
Central Asian ◽  
High K ◽  
Three Stages ◽  
Late Neoproterozoic

The Central Asian Orogenic Belt had been formed by amalgamation of voluminous subduction–accretionary complexes during the Late Neoproterozoic to the Mesozoic period. Mongolia is situated in the center of this belt. This study presents new zircon U–Pb geochronological, whole-rock major and trace element data for granitoids within central Mongolia and discusses the tectonic setting and evolution of these granitic magmas during their formation and emplacement. The zircon U–Pb ages indicate that the magmatism can be divided into three stages: the 564–532 Ma Baidrag granitoids, the 269–248 and 238–237 Ma Khangai granitoids. The 564–532 Ma Baidrag granitoids are adakitic, have an I-type affinity, and were emplaced into metamorphic rocks. In comparison, the 269–248 Ma granitoids have high-K, calc-alkaline, granodioritic compositions and are I-type granites, whereas the associated the 238–237 Ma granites have an A-type affinity. The 564–532 Ma Baidrag and 269–248 Ma Khangai granitoids also both have volcanic arc-type affinities, whereas the 238–237 Ma granites formed in a post-collisional tectonic setting. These geochronological and geochemical results suggest that arc magmatism occurred at the 564–532 Ma which might be the oldest magmatic activity in central Mongolia. Between the Baidrag and the Khangai, there might be paleo-ocean and the oceanic plate subducted beneath the Khangai and produced voluminous granite bodies during the 269–248 Ma. After the closure of the paleo-ocean, the post collisional granitoids were formed at the 238–237 Ma based on the result of later granitoids in the Khangai area.

scholarly journals Petrographic Characteristics and Geochemistry of Volcanic Rocks in the Kyaukmyet Prospect, Monywa District, Central Myanmar

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Toe Naing Oo ◽  
Agung Harijoko ◽  
Lucas Donny Setijadji
Keyword(s):  
Middle Miocene ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Field ◽  
Research Area ◽  
Eu Anomaly ◽  
Volcanic Suite ◽  
Copper Gold ◽  
Arc Setting ◽  
Insight Into

The Kyaukmyet prospect lies approximately 5 km ENE of the highsulfidation Kyisintaung copper-gold deposit, Monywa district, central Myanmar. Geologically, the research area is remarked by magmatic extrusion that occurred during the Late Oligocene to Middle Miocene of Magyigon Formation which led to the outcrops of volcanic rocks. Study detailed on petrographical and geochemical of the Kyaukmyet volcanic rocks has not been performed before the present work. The principal aim of this paper is to document the petrographical and geochemical characteristics of volcanic suite rocks exposed in the Kyaukmyet prospect. The results of this data have provided insight into the origin of the rocks and petrogenetic processes during evolution. Petrographically, all the studied volcanic rocks in the research area show that trachytic and porphyritic textures with phenocrysts of quartz, plagioclase, and K-feldspar which are embedded in a fine to medium grained groundmass. The accessory minerals of this rock consist of biotite, chlorite and opaque mineral.Geochemically, these volcanic rocks having calc-alkaline nature and classified as volcanic field (rhyolite) as well as volcanic arc setting. Based on the chondrite normalized spider diagram, LREE has enriched to HREE in this area which indicated negative Eu anomaly and subduction tectonic setting.

The role of the Kyrenia Range Lineament, Cyprus, in the geological evolution of the eastern Mediterranean area

1986 ◽  
Vol 317 (1539) ◽  
pp. 141-177 ◽  
Keyword(s):  
Large Scale ◽  
Carbonate Platform ◽  
Eastern Mediterranean ◽  
Tectonic Setting ◽  
Ocean Basin ◽  
Strike Slip ◽  
Passive Margin ◽  
Late Triassic ◽  
Metamorphic Rocks ◽  
Mountain Areas

Rewarding insights into major crustal lineaments come from the integrated study of well exposed examples. One is the Kyrenia Range, a narrow arcuate lineament of several hundred kilometres in length comprising northern Cyprus and its offshore extension. The Kyrenia Range consists mostly of Mesozoic and Tertiary sedimentary and subordinate volcanic and metamorphic rocks, disposed in four rock groups separated by unconformities recording deformation events. The lineament is dominated by a steeply dipping composite thrust pile located partly along, and partly straddling, the abrupt northward termination of crust similar to the Troodos Igneous Complex at depth. The 200 Ma history of the lineament involved episodic rift, passive-margin, active-margin, strike-slip and uplift phases. The area was rifted off Gondwana in the late Triassic to form a southerly Turkish microcontinent capped by a gently subsiding carbonate platform. After formation of a small ocean basin to the south during the Cretaceous (Troodos ocean), northward subduction began (?Santonian). The first major deformation (D1) is attributed to pervasive (?dextral) strike-slip, which removed the Mesozoic passive margin and brecciated and metamorphosed the remaining platform. In the Maastrichtian and early Tertiary the area subsided and scree breccias were shed from scarps into pelagic carbonate-depositing seas, while bimodal within-plate-type lavas were erupted in an extensional setting influenced by strike-slip. By mid Eocene time, shortening, first evidence by flysch and olistostrome deposition, culminated in strong southward thrusting (D2) and localized metamorphism. Northward subduction south of Cyprus ensued and the range lay in an extensional fore-arc setting in late Eocene and Miocene time. The area then subsided dramatically and accumulated thick turbidite sequences derived from eroding Tauride Mountain areas to the northeast. Faulting and general uplift in the late Miocene was followed by renewed compressional deformation climaxing in mid Pliocene time (D3) with large-scale thrusting and tilting. Pulsed vertical uplift continued through the Quaternary. Similar volcanic and metamorphic rocks formed along the Kyrenia Lineament at intervals. Sedimentary rocks emerge as the most sensitive tectonic setting indicators. Long-lived lineaments like the Kyrenia Range are inherently very complicated, and perceived simple solutions in other cases should be viewed with some scepticism.

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