scholarly journals Mg-Fe-RICH AMPHIBOLES ASSOCIATED TO PYROCLASTICS FROM SANTORINI ISLAND, SOUTH AEGEAN SEA VOLCANIC ARC, GREECE

2007 ◽  
Vol 40 (2) ◽  
pp. 851
Author(s):  
K. Kitsopoulos
Keyword(s):  
Water Content ◽  
Volcanic Activity ◽  
Volcanic Rocks ◽  
Aegean Sea ◽  
Primitive Mantle ◽  
Mineral Phase ◽  
Volcanic Arc ◽  
Mineral Phases ◽  
Mafic Magmas ◽  
Silicic Magmas

Amphibole bearing volcanic products in Santorini are restricted to the early volcanic activity expressed in the Akrotiri peninsula. This fact distinguishes these early products from the rest of the volcanic rocks of Santorini. The Fe-Mg-rich mineral phases, associated to the Akrotiri silicic pyroclastics which were analysed can be classified as Mg-Fe rich type of amphibole. This type of amphibole has not been reported before in volcanic rocL· from the South Aegean Volcanic Arcr. The presence of such a high Fe-Mg mineral phase in silicic pyroclastics in Santorini is constant with the involvement of primitive, mantle derived, mafic magmas, with some considerable water content, and which have been differentiated, before they are mixed with more silicic magmas at a shallower crustal level.

Automated mineral analysis in TASK8

1990 ◽  
Vol 48 (2) ◽  
pp. 212-213
Author(s):  
William F. Chambers ◽  
Arthur A. Chodos ◽  
Roland C. Hagan
Keyword(s):  
National Laboratory ◽  
Control Program ◽  
Mineral Analysis ◽  
Alamos National Laboratory ◽  
Mineral Phase ◽  
Los Alamos National Laboratory ◽  
California Institute Of Technology ◽  
Mineral Phases ◽  
Letter Code ◽  
Institute Of Technology

TASK8 was designed as an electron microprobe control program with maximum flexibility and versatility, lending itself to a wide variety of applications. While using TASKS in the microprobe laboratory of the Los Alamos National Laboratory, we decided to incorporate the capability of using subroutines which perform specific end-member calculations for nearly any type of mineral phase that might be analyzed in the laboratory. This procedure minimizes the need for post-processing of the data to perform such calculations as element ratios or end-member or formula proportions. It also allows real time assessment of each data point.The use of unique “mineral codes” to specify the list of elements to be measured and the type of calculation to perform on the results was first used in the microprobe laboratory at the California Institute of Technology to optimize the analysis of mineral phases. This approach was used to create a series of subroutines in TASK8 which are called by a three letter code.

scholarly journals Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Activity ◽  
Volcanic Rocks ◽  
Active Tectonics ◽  
Normal Fault ◽  
Aegean Sea ◽  
Northern Margin ◽  
The North ◽  
Eastern Aegean ◽  
Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

scholarly journals Nisyros Volcanic Island: A Geosite through a Tailored GIS Story

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 132
Author(s):  
Varvara Antoniou ◽  
Paraskevi Nomikou ◽  
Dimitrios Panousis ◽  
Effrosyni Zafeirakopoulou
Keyword(s):  
Spatial Data ◽  
Hot Springs ◽  
Volcanic Rocks ◽  
Data Communication ◽  
Aegean Sea ◽  
Volcanic Island ◽  
Eastern Aegean ◽  
Strongly Connected ◽  
Historical Heritage ◽  
Available Information

The volcanic island of Nisyros (Greece) is here presented as it presents unique characteristics being a Quaternary volcano in the eastern Aegean Sea, composed of volcanic rocks, and featuring a central caldera that is surrounded by volcanic domes and thick lavas. Its history is strongly connected to the volcano impressing the visitors with steaming hydrothermal craters, intensive smell of sulfur and fumarolic gases, and hot springs. Due to its morphology and geographical position, its cultural and historical heritage has been unchanged in time, bequeath to the island plenty of churches, monasteries with hagiographic frescoes, castles, caves, and spas. To present the geodiversity, the cultural environment, and the biodiversity of this geosite, a relatively new geographic approach was used, ESRI Story Maps. Being web-based applications, they are widespread as an interactive responsive tool used for spatial data communication and dissemination, by combining thematic 2D and 3D webmaps, narrative text, and multimedia content. Such applications can be an ideal way for presenting the available information of places characterized as geosites or protected areas worldwide, providing quick access to the available information to a broader, non-technical audience, developing the interest, and possibly motivating the public to learn more or visit them.

Deep Structure and Active Tectonics of the South Aegean Volcanic Arc

Elements ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 153-158 ◽  
Author(s):  
Costas B. Papazachos
Keyword(s):  
Deep Structure ◽  
Active Tectonics ◽  
Aegean Sea ◽  
Low Velocity ◽  
Volcanic Arc ◽  
High Attenuation ◽  
Global Positioning ◽  
Back Arc ◽  
The Impact ◽  
Subducting Slab

The seismotectonic setting of the Aegean Sea, based on information from seismicity, neotectonics and global positioning system studies, is characterized by a sharp transition from a compressional outer arc to a complex back-arc, with an approximate north–south extension along the volcanic arc. Seismicity and 3-D tomography studies reveal the geometry of the subducting slab and image the low-velocity/high-attenuation mantle wedge at depths of 50–80 km beneath the volcanic arc where magma is generated. The 1956 Amorgos M7.5 earthquake and the impact from its seismic shaking and landslide-triggered tsunamis are discussed in the context of the regional seismotectonic setting.

scholarly journals The main pulse of the Siberian Traps expanded in size and composition

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
L. E. Augland ◽  
V. V. Ryabov ◽  
V. A. Vernikovsky ◽  
S. Planke ◽  
A. G. Polozov ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Volcanic Rocks ◽  
West Siberia ◽  
Main Pulse ◽  
Environmental Consequences ◽  
Siberian Traps ◽  
Minimum Age ◽  
Area North ◽  
Permian Mass Extinction ◽  
Compositional Diversity

AbstractEmplacement of large volumes of (sub)volcanic rocks during the main pulse of the Siberian Traps occurred within <1 m.y., coinciding with the end-Permian mass extinction. Volcanics from outside the main Siberian Traps, e.g. Taimyr and West Siberia, have since long been correlated, but existing geochronological data cannot resolve at a precision better than ~5 m.y. whether (sub)volcanic activity in these areas actually occurred during the main pulse or later. We report the first high precision U-Pb zircon geochronology from two alkaline ultramafic-felsic layered intrusive complexes from Taimyr, showing synchronicity between these and the main Siberian Traps (sub)volcanic pulse, and the presence of a second Dinerian-Smithian pulse. This is the first documentation of felsic intrusive magmatism occurring during the main pulse, testifying to the Siberian Trap’s compositional diversity. Furthermore, the intrusions cut basal basalts of the Taimyr lava stratigraphy hence providing a minimum age of these basalts of 251.64 ± 0.11 Ma. Synchronicity of (sub)volcanic activity between Taimyr and the Siberian Traps imply that the total area of the Siberian Traps main pulse should include a ~300 000 km2 area north of Norilsk. The vast aerial extent of the (sub)volcanic activity during the Siberian Traps main pulse may explain the severe environmental consequences.

Geochemistry of Sainte-Marguerite volcanic rocks: implications for the evolution of Silurian–Devonian volcanism in the Gaspé Peninsula

2008 ◽  
Vol 45 (1) ◽  
pp. 15-29 ◽  
Author(s):  
Alan D’hulst ◽  
Georges Beaudoin ◽  
Michel Malo ◽  
Marc Constantin ◽  
Pierre Pilote
Keyword(s):  
Lower Devonian ◽  
Volcanic Rocks ◽  
Magma Source ◽  
Volcanic Arc ◽  
Lower Silurian ◽  
Trace Element Signature ◽  
Arc Setting ◽  
Back Arc ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

The Lower Devonian Sainte-Marguerite volcanic rocks are part of a Silurian–Devonian volcanic sequence deposited between the Taconian and Acadian orogenies in the Gaspé Peninsula, Quebec, Canada. The Sainte-Marguerite unit includes basaltic and dacitic lava flows with calc-alkaline and volcanic-arc affinities. Such affinities are also recorded by the trace-element signature in Lower Silurian and most Lower Devonian volcanic units of the Gaspé Peninsula. However, most of the other Silurian–Devonian volcanic rocks occurring in the Gaspé Peninsula have been previously interpreted to have erupted in an intracontinental setting. A back-arc setting for the Gaspé Peninsula between the Taconian and Acadian orogenies could account for these subduction volcanic-arc signatures, though a metasomatized lithospheric mantle magma source, unrelated to subduction, cannot be excluded. Lower Silurian and Lower Devonian volcanic rocks in the central part of the Gaspé Peninsula show an arc affinity, whereas Upper Silurian and Lower to Middle Devonian volcanic rocks, located in the south and north of the Gaspé Peninsula, respectively, show a within-plate affinity. The Lower Devonian Archibald Settlement and Boutet volcanic rocks of the southern and northern Gaspé Peninsula, respectively, show a trend toward a within-plate affinity. This suggests that within-plate volcanism migrated from south to north through time in an evolving back-arc environment and that the subduction signature of Lower Silurian and Lower Devonian rocks results from a source that melted only under the central part of the Gaspé Peninsula.

scholarly journals Volcanic activity and gas emissions along the South Sandwich Arc

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
Emma J. Liu ◽  
Kieran Wood ◽  
Alessandro Aiuppa ◽  
Gaetano Giudice ◽  
Marcello Bitetto ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Volcanic Activity ◽  
Emission Rate ◽  
Tectonic Setting ◽  
Hydrothermal Systems ◽  
Molar Ratio ◽  
The South ◽  
Gas Emissions ◽  
Volcanic Arc

AbstractThe South Sandwich Volcanic Arc is one of the most remote and enigmatic arcs on Earth. Sporadic observations from rare cloud-free satellite images—and even rarer in situ reports—provide glimpses into a dynamic arc system characterised by persistent gas emissions and frequent eruptive activity. Our understanding of the state of volcanic activity along this arc is incomplete compared to arcs globally. To fill this gap, we present here detailed geological and volcanological observations made during an expedition to the South Sandwich Islands in January 2020. We report the first in situ measurements of gas chemistry, emission rate and carbon isotope composition from along the arc. We show that Mt. Michael on Saunders Island is a persistent source of gas emissions, releasing 145 ± 59 t day−1 SO2 in a plume characterised by a CO2/SO2 molar ratio of 1.8 ± 0.2. Combining this CO2/SO2 ratio with our independent SO2 emission rate measured near simultaneously, we derive a CO2 flux of 179 ± 76 t day−1. Outgassing from low temperature (90–100 °C) fumaroles is pervasive at the active centres of Candlemas and Bellingshausen, with measured gas compositions indicative of interaction between magmatic fluids and hydrothermal systems. Carbon isotope measurements of dilute plume and fumarole gases from along the arc indicate a magmatic δ13C of − 4.5 ± 2.0‰. Interpreted most simply, this result suggests a carbon source dominated by mantle-derived carbon. However, based on a carbon mass balance from sediment core ODP 701, we show that mixing between depleted upper mantle and a subduction component composed of sediment and altered crust is also permissible. We conclude that, although remote, the South Sandwich Volcanic Arc is an ideal tectonic setting in which to explore geochemical processes in a young, developing arc.

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