Chronostratigraphic Analysis of the Evolution of the Christiana-Santorini-Kolumbo Volcanic Field

2021 ◽  
Author(s):  
Jonas Preine ◽  
Christian Hübscher ◽  
Jens Karstens ◽  
Paraskevi Nomikou ◽  
Timothy Druitt ◽  
...  
Keyword(s):  
Aegean Sea ◽  
Volcanic Field ◽  
Pyroclastic Flows ◽  
Seismic Profiles ◽  
The Past ◽  
Stratigraphic Framework ◽  
Volcanic Chain ◽  
Recent Phase ◽  
Extensive Collection ◽  
Intrusive Activity

<p>The Christiana-Santorini-Kolumbo (CSK) volcanic field in the South Aegean Sea is one of the most active volcanic-tectonic lineaments in Europe, having produced numerous explosive eruptions, catastrophic earthquakes, and disastrous tsunamis in the past 350,000 years. The present-day Santorini caldera is located in the centre of the NE-SW trending CSK field, which extends for more than 60 km from the extinct Christiana volcano in the southwest to the active submarine Kolumbo volcano northeast of Santorini. While the onshore architecture of Santorini has been well studied, little is known about its offshore architecture. Further, the past volcanism of Kolumbo is only known for its last eruption in 1650 AD and that of Christiana is completely unknown. Based on the available onshore datings of the volcanic formations, it has been proposed that volcanism in the CSK field initiated at Christiana, then migrated northeast towards Santorini and later to Kolumbo. This, however, has yet to be confirmed by offshore investigations. To fully constrain and understand the initiation and evolution of volcanism in the CSK field, we combine an extensive collection of high-resolution multichannel and vintage seismic data covering the entire zone.</p><p>With these seismic profiles, we are able to (1) correlate the seismo-stratigraphy of the Christiana basin west of Santorini with that of the Anhydros Basin east of Santorini, (2) identify major phases of extrusive and intrusive activity of individual volcanic vents, and (3) establish a regional chrono-stratigraphic framework in which we chronologically integrate these phases. We conclude that volcanism occurred repetitively during distinct phases of activity, which are separated from each other by periods with little or no volcanic activity. The onset of volcanism occurred without the generation of significant pyroclastic flows and was mainly characterized by shallow intrusions, clearly visible at Christiana, at its neighbouring volcanic cones, and at the southwestern flank of Akrotiri. The next phase saw the formation of the Kolumbo Volcanic Chain in the Anhydros Basin and the formation of sill intrusions in the Christiana Basin, which we find below a chaotic, presumably pyroclastic unit. This was followed by a major regional event on Santorini, during which a thick transparent subunit was deposited in all surrounding basins. The most recent phase was dominated by the volcanoclastic deposits from Santorini’s eruptive cycles and the recent eruption of Kolumbo. Using estimates of sedimentation rates, we convert this chrono-stratigraphic scheme into an approximate timeline, which implies that the initiation of volcanism occurred during Late Pliocene to Early Quaternary - much earlier than revealed by onshore dating.</p>

Westward propagation of thrusts in the external Western Alps (France) reappraised from an updated chronostratigraphy of the Miocene Molasses

2021 ◽  
Author(s):  
Amir Kalifi ◽  
Philippe-Hervé Leloup ◽  
Philippe Sorrel ◽  
Albert Galy ◽  
François Demory ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Foreland Basin ◽  
Western Alps ◽  
Seismic Profiles ◽  
Stratigraphic Framework ◽  
Basin Scale ◽  
Deformation Kinematics ◽  
Westward Migration ◽  
External Part ◽  
Tectonics And Sedimentation

<p>The fact that the western Alps Miocene foreland basin succession is poorly dated impacts directly our understanding of the deformation kinematics of that part of the external part of the Alpine belt (France). Here we propose a multidisciplinary approach aiming at building a robust tectono-stratigraphic framework of the Miocene deposits at the basin scale (northern subalpine massifs, southern Jura, Royans, Bas-Dauphiné and La Bresse basins). Sr isotopes stratigraphy combined with magnetostratigraphy and biostratigraphy enable sequence stratigraphy subdivisions S1 to S8 between the Upper Aquitanian (-21 Ma) and the Tortonian (-9 Ma) dated with a precision <0.5 Ma. These results highlight four different palaeogeographical domains during the Miocene: (i) the oriental domain with depositional sequences S1a to S3 (~21.3 to 15Ma), (ii) the median domain, in which sequences S2, S3, S4 and S5 occurred (~17.8 to 14Ma), (iii) the occidental domain with sequences S2 to S8 (~17.8 to ~9.5Ma); and (iv) the Bressan domain, in which sequences S6 to S8 are found (~ 11.5 to ~9.5Ma).</p><p>This revised chronostratigraphy was complemented with a structural and tectono-sedimentary study based on new fieldwork data and a reappraisal of regional seismic profiles, allowing to highlight five major faults zones (FZ). It appears that the oriental, median and occidental paleogeographical domains are delineated by FZ1, FZ2 and FZ3, therefore suggesting a strong interplay between tectonics and sedimentation. Evidences of syntectonic deposits and a westward migration of the depocenters impart the following deformation chronology : a Oligocene compressive phase (P1) corresponding to thrusting above FZ1 rooted east (above) Belledonne, which generated reliefs that limited the early Miocene transgression to the east; an Early- to Middle Miocene W-WNW/E-ESE-directed compressive phase (P2) involving the Belledonne massif basal thrust, which between 18.05 +/- 0.15 Ma and 12Ma successively activated the Salève thrust fault, and the FZ2 to FZ5 from east to west. P2 deeply impacted the Miocene palaeogeographical evolution by a rapid westward migration of depocenters in response to the exhumation of piggy-back basins above the growing fault zones; a last Tortonian phase (P3), less well constrained, apparently implied a significant uplift in the subalpine massifs, combined with the activation of the frontal Jura thrust.</p>

scholarly journals Plio-Quaternary history of the Turkish coastal zone of the Enez-Evros Delta: NE Aegean Sea

2001 ◽  
Vol 2 (2) ◽  
pp. 95 ◽  
Author(s):  
B. ALPAR
Keyword(s):  
Late Pleistocene ◽  
Sand Dunes ◽  
Aegean Sea ◽  
Interglacial Period ◽  
Shelf Area ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
Alluvial Deposits ◽  
History Of ◽  
Quaternary History

The Enez-Evros Delta, NE Aegean Sea, is located in one the most important wetlands in the world with its sandy offshore islands, abandoned channel mouths, sand-dunes, shoals, marshlands, saline lagoons and saltpans. It comprises very well developed sedimentary units and a prodelta lying on an older submarine delta. The present day elevations of the middle-late Pleistocene marine terraces indicate a regional tectonic uplift in the area. Due to lack of geophysical and bore hole data and partly due to its strategic position, the structural and stratigraphic features of the submarine extension of the delta are not known in detail. In this paper, Plio-Quaternary history of this delta and its submarine part on the Turkish shelf was explored by using high-resolution shallow reflection seismic profiles. The delta is formed by the alluvial deposits of the Enez-Evros River and shaped by their interaction with the sea. It takes place in front of a large and protected ancient bay which was filled rapidly over millennia. The sediments in the plateau off the river are principally pro-deltaic with muddy areas near the river mouths changing to muddy sand further out. The sea-level changes in Plio-Quaternary were characterised by three different seismic stratigraphic units on the folded Miocene limestone basement. In the late Pleistocene, the shelf area over an Upper Miocene basement was flooded during the Riss-Würm interglacial period, exposed in the Würm glacial stage, and flooded once again during the Holocene transgression.

The Christiana–Santorini–Kolumbo Volcanic Field

Elements ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 171-176 ◽  
Author(s):  
Paraskevi Nomikou ◽  
Christian Hübscher ◽  
Steven Carey
Keyword(s):  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Aegean Sea ◽  
Volcanic Eruptions ◽  
Volcanic Field ◽  
Explosive Eruptions ◽  
Human Populations ◽  
Mass Wasting ◽  
Geological Processes ◽  
Research Activities

The Christiana–Santorini–Kolumbo volcanic field in the South Aegean Sea (Greece) is one of the most important in Europe, having produced more than 100 explosive eruptions in the last 400,000 years. Its volcanic centers include the extinct Christiana Volcano and associated seamounts, Santorini caldera with its intracaldera Kameni Volcano, Kolumbo Volcano, and 24 other submarine cones of the Kolumbo chain. Earthquakes, volcanic eruptions, submarine mass wasting, neotectonics and gas releases from these centers pose significant geohazards to human populations and infrastructures of the Eastern Mediterranean region. Defining the geological processes and structures that contribute to these geohazards will provide an important framework to guide future monitoring and research activities aimed at hazard mitigation.

THE PLECOPTERA OF WESTERN MONTANA

1939 ◽  
Vol 71 (10) ◽  
pp. 208-211 ◽  
Author(s):  
Gordon B. Castle
Keyword(s):  
Aquatic Insects ◽  
Western Montana ◽  
The Past ◽  
Extensive Collection

The streams and lakes of western Montana offer a variety of habitats for species of aquatic insects but heretofore extensive collection and study of these forms has not been undertaken. During the past two years collections of both nymphs and adults have been made on several streams. The Plecoptera in these collections include the undescribed nymphs of Nemoura cinctipes Banks and several species which have not been reported for Montana.

Coastal Changes in South Wales—The Excavation of an Old Beach

1933 ◽  
Vol 70 (12) ◽  
pp. 541-549 ◽  
Author(s):  
Leonard S. Higgins
Keyword(s):  
Surface Conditions ◽  
The Past ◽  
South Wales ◽  
History Of ◽  
Recent Phase ◽  
Coastal Changes ◽  
East And West

While investigating the problem of coastal changes in South Wales, and examining 1 the area of the Merthyr Mawr Warren (Fig. 1) for this purpose, the differences, observable in the surface conditions to-day, and evident in the records of the past, between the areas east and west of a line approximating to the Burrows Well stream, suggested that the relatively recent physical history of the two sections of the area had not been similar. The greater width in the east suggested recent accumulation in this section, and the presence of what appeared to be successively formed littoral dunes pointed to a relatively recent phase of prograding, while the topography made it possible that these changes were related to the mouth of the River Ogmore.

scholarly journals ATLANTIS IN SPAIN IV

2017 ◽  
Vol 43 (1) ◽  
pp. 126
Author(s):  
S.P Papamarinopoulos
Keyword(s):  
Building Material ◽  
Simulation Experiment ◽  
Optimal Solution ◽  
Aegean Sea ◽  
The Other ◽  
Southern Spain ◽  
Statistical Criterion ◽  
The Past ◽  
Geological Age ◽  
Main City

Many analysts in the past faced Atlantis’ main city with the same way they faced his idealised concentric cities which he described in his dialogues. However, Atlantis’ concentric city has a marked difference which is recognisable if the analyst has geological knowledge. For instance the concentric scheme, the geothermal springs and the black, white and red rocks correspond in volcanogenic, impactogenic and diapeirogenic craters. It is known that building material from rocks existing in the vicinity of the two first, from the three, types of craters have been used in the past. It is also known that cities have been developed both on volcanogenic craters such as Santorin in the Aegean Sea, or on impactogenic craters such as in Nordlichen in Germany and in Yemen’s capitol respectively. A simulation experiment was carried out exactly in the platonic geomorphological conditions assuming that the concentric scheme could be of impactogenic origin. The result showed that such multi-ringed crater exhibits the platonic characteristics presented in Critias. However, such solution is not unique because the other two types of craters have not been tested yet. The statistical criterion which may be applied in all three simulations in the described platonic environment will decide by itself which is the most optimal solution between all three. Many experts who know nothing about Plato’s views about science and mythology can not differentiate between genuine and fabricated myths utilised by Plato. Most of them do not understand that the multiringed crater called Atlantis too by Plato is revealed in the ancient myths prior to Plato and was placed by these writers West of the Gibraltar Straits. Philostratus, in Roman times, is the only Greek writer who described its geological nature in detail and presented its position in Southern Spain. That crater Geryonis was associated with Heracles’ visit in Iberia. In the latter’s sea environment there are several submerged gigantic diapeirogenic craters and a small one visible even today in Andalucía’s. The geological age of the submerged craters, in Cadiz, precedes the prehistoric Greeks’ and Iberians’ presence in the area. One of them possibly became the object of observations of prehistoric Greek mariners who passed Heracles’ Pillars and it was interpreted as Poseidon’s act. These Greek mariners were accustomed to interpret craters in the Aegean Sea such the Nisyros’, for instance, one as Poseidon’s act too.

scholarly journals Aspects of the petrology and geochemistry of the Huckleberry Ridge Tuff, Yellowstone

2021 ◽  
Author(s):  
◽  
Elliot Swallow
Keyword(s):  
Numerical Models ◽  
Volcanic Field ◽  
Fall Deposit ◽  
Magmatic System ◽  
Magmatic Complex ◽  
Isotopic Compositions ◽  
Stratigraphic Framework ◽  
System 2 ◽  
Geochemical Investigation ◽  
System 1

<p>Silicic (i.e. dacitic-rhyolitic) magmatic systems have the potential to generate large, explosive caldera-forming eruptions which have global effects and consequences. How, and over what timescale, magma accumulates and is stored in the upper crust are key aspects in understanding such systems and their associated hazards. The absence of such eruptions in the historical record, however, has forced understanding of these systems to be developed through numerical models or the study of the deposits in the geological record. Numerical models primarily focus on the long-term generation but instantaneous eruption of single magma (i.e. melt-dominant) bodies. In contrast, the stratigraphic and geochemical nature of eruption deposits often show features more consistent with complex magmatic systems comprising multiple melt-dominant bodies that may have formed rapidly but erupted episodically. Further studies of past eruption deposits are valuable, therefore, in reconstructing silicic magmatic systems and highlighting the nature of melt-dominant body generation and storage.  To this end, this thesis examines the 2.08 Ma, ∼2,500 km³ Huckleberry Ridge Tuff (HRT), Yellowstone Plateau volcanic field (YPVF), U.S.A, the deposit of the first and largest of three caldera-forming eruptions in the YPVF. The HRT comprises an initial fall deposit followed by three ignimbrite members (A, B and C) with a second fall deposit between members B and C. Despite emanating from an archetypal silicic volcanic field, minimal previous work has been undertaken on the geochemical nature of the HRT but it is thought to conform to traditional, unitary magma body ideas. A revised stratigraphic framework, detailing an episodic and prolonged initial fall deposit, identification of a weeks-months time gap between members A and B, and a similar but longer years-decades hiatus in activity between members B and C provides the context for this geochemical investigation. A large sample suite representative of the diverse range of physical characteristics of clasts and material found in the HRT was analysed. In situ micro-analysis of matrix glass (major and trace elements) and crystals (major elements) in the initial fall deposit are coupled with major and trace element, and isotopic compositions of single silicic clasts (i.e. pumice/fiamme) from all three ignimbrite members, supplemented by in situ analysis of their crystals and groundmass glass. These data are used to reconstruct the silicic magmatic system. Furthermore, major and trace element, andisotopic compositions of rare mafic (i.e. basaltic to andesitic) material found in members A and B provide an insight into the thermal and chemical drivers of HRT silicic volcanism.  This macro- and micro-analytical investigation using multiple techniques reveals remarkable complexity within the large-scale HRT magmatic complex. Four geochemically distinct magmatic systems are differentiated on single clast elemental and isotopic characteristics that are further reflected in crystal and glass compositions. Two of these systems (1 and 2) were active in the initial fall deposit and member A. Magmatic system 1 is volumetrically dominant in the HRT and is characterised by moderate-high Ba single clast (450-3540 ppm) and glass (100-3360 ppm) compositions, in contrast to the distinctly low-Ba (≤250 ppm single clast, <65 ppm glass Ba contents) magmatic system 2. Both these magmatic systems exhibit clustered glass compositions, indicating multiple, laterally-adjacent melt-dominant bodies were present, and shared moderate isotopic compositions (e.g. ⁸⁷Sr/⁸⁶SrAC = 0.70950-0.71191) are explicable by a multi-stage partial melting-fractional crystallisation petrogenesis. The time break between members A and B is associated with mixing and mingling within magmatic system 1, related to a renewed influx of mafic material, and a cessation of activity of system 2, which is absent from member B. The time break between members B and C reflects significant changes within the magmatic complex. Magmatic system 2 is rejuvenated and melt-dominant bodies associated with two new magmatic systems (3 and 4) are formed, with at least system 3 comprising multiple bodies. These latter two magmatic systems strongly differ in their elemental characteristics (system 3: high SiO₂ [75-78 wt% SiO₂]; system 4: dacite-rhyolite [66-75 wt% SiO₂]). Despite this, they have similar and highly radiogenic (e.g. ⁸⁷Sr/⁸⁶SrAC = 0.72462-0.72962) isotopic compositions indicating shared extensive incorporation of Archean crust. They also contrast in their relation to mafic compositions, with system 4 associated with olivine tholeiitic compositions erupted prior to and following the HRT in the YPVF. In contrast, system 3, like systems 1 and 2, is associated with high-Ba, high-Zr mafic compositions found co-erupted in HRT members A and B. These compositions are similar to lava flows erupted further west at the Craters of the Moon field, and are interpreted as representing partial melts from regions in the lithospheric mantle enriched by high-T, P fluids emanating from the subducted Farallon slab.  Overall, the HRT magmatic complex was remarkably heterogeneous. Two contemporaneous mafic root zones drove four silicic magmatic systems, episodically active throughout the eruption. At least three of these systems comprised multiple laterally-adjacent melt-dominant bodies. Intra-eruption time breaks are associated with broad-scale reorganisation of the magmatic complex. This complexity highlights the utility of a detailed, systematic, multi-technique geochemical investigation, within a stratigraphic framework, of the deposits of large silicic caldera-forming eruptions, and breaks new ground in the understanding of such systems.</p>

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