Volcanism

The felsic lavas of the Bamenda Mountains, in the main part of the Cameroon Volcanic Line, are mainly represented by trachytes, with subordinated benmoreites and alkaline to peralkaline rhyolites. New K–Ar geochronological data define two main volcanic episodes, the first one between 18 and 22Ma, and the second one from 12.5 to 13.5Ma. Geochemical data indicate that these felsic rocks

The impact that volcanic eruptions may have upon environments far from the volcanic source is conventionally assumed to depend on climatic modification by emitted gases. However, recent research has suggested that the damage caused by the direct impact of volcanic gases, mainly H 2SO 4, may be profound. This paper highlights the severity of this mechanism by reference to human sickness and death in France and contiguous with the eruption of the Laki fissure in Iceland in 1783. This work demonstrates the gains which may be made by interdisciplinary teams of researchers and illustrates the valuable knowledge that remains to be revealed by further research in the French historical record. To cite this article: J. Grattan et al., C. R. Geoscience 337 (2005).

The shrinkage of the Lisan Lake (LL) to form the recent Dead Sea (DS) was mainly a result of the reduction of the catchment area from around 157,000 km2 during Late Pleistocene to 43,000 km2 presently. The reduction in the catchment area resulted from the eruption and spread of the basalt flows of Jabal Arab-Druz (JAD), which together with the resulting deposition of thick rock debris and gravels occupied the drainage system. The filling of the pre-basalt drainage system, which used to feed the Dead Sea, with basalts and alluvial sediments blocked the inflows from reaching the Dead Sea. Local base levels along the basalt flow boarders such as Azraq Oasis, Sirhan Basin and Damascus Oasis, and numerous pools and mud flats were created.

Computerized evaluation of Vibroseis similarity test data is the logical consequence of the increasing quality requirements for signal reproducibility and for synchronization of vibrators. The differences in start time and phase as well as an indication of local phasing problems between any two Vibroseis signals can be obtained from an analysis of the difference of their respective phase spectra. This method appears to be accurate and stable with respect to harmonics which usually plague the signals from transducers monitoring the motion of the vibrators'base plates.

Thick silicic tuff sequences and silicic intrusives are found in deep wells drilled at the Muara Laboh and Rantau Dedap Geothermal Fields, Sumatra, Indonesia. Petrographic and petrophysical investigation of cuttings, core, gamma ray and image logs were used to understand the silicic stratigraphic controls on reservoir permeability. Regional geologic constraints and limited U-Pb zircon ages show that silicic explosive volcanism most likely occurred mainly during the Miocene to Plio-Pleistocene, and locally continuing into the Holocene. Wells in both fields show that silicic tuff sequences reach thicknesses of 500 to >1000 meters, and silicic intrusive complexes intrudes to reservoir depths. In Muara Laboh, thick silicic tuffs are found in a basin generated between major strike-slip fault segments. The dominant rock type is variably welded to non-welded silicic ash-flow tuff with a variety of devitrification textures. A long-lived sheared and altered granite-granodiorite-microdiorite intrusive complex representing multiple magmatic episodes (96 to 20 Ma) occurs in the SW sector of the field. In Rantau Dedap, similar silicic tuff sequences are found as caldera fill deposits overlain by debris flows. A weakly altered, poorly deformed granite to granodiorite intrusive complex occurs at depth. The silicic volcanics have high resistivity in image logs, fine fragmental textures (tuffs) to massive textures (intrusives), and high gamma ray counts (65 to 200 API) in both fields. Fracture intensity of the thick silicic tuff sequences increases with welding, primary devitrification, and possibly the thickness and cooling history of individual eruptive units. Major feed zones are associated with faulted lithological contacts and very limited at thick silicic tuffs in Muara Laboh. Fluid entries at Rantau Dedap are most abundant in the relatively thin Upper Rhyolite Tuff and underlying Dacite Tuff, and near the basal contact of the thick Lower Dacite Tuffs with intrusions. Permeable zones are encountered at the margin of the intrusive complexes in both fields.

In the last twenty years, archaeological excavations and public works have uncovered new information about the stratigraphy of Lake Albano maar and the results have engaged researchers in a discussion
about the real occurrence of volcanic activity and consequent CO2 release and lake overflow. A key question remains regarding how far in the past this activity can be dated. On the bias of a multidisciplinary approach called geomythology, this poster sheds light on a much-debated issue concerning the supposed volcanic activity of Lake Albano maar (Colli Albani – Rome) in Antiquity. In fact, Latin and Greek sources speak of the marvel of the spillover of Lake Albano in 398 BC during the
war against Veio and the hub of the modern debate turns on whether to put confidence in it or not. Latin mythology provides evidence that the Romans somehow preserved the memory of the geological nature
of the lake: the overflowing of the lake was perceived as a punishment from Neptune; during Volcanalia, real fishes were thrown into the fire and bronze ones were offered as sacrifice on Mount Albano. The
recurring image of the fire in the water is remarkable for its repeated occurrence. Even though there is still need to prove the veracity of events reported by ancient sources, it is undeniable that Romans were
indeed aware of the volcanic origin of the lake - and that they may have witnessed some sort of manifestation related to the volcano. Mythology can suggest an interpretation of events which are only
partially recorded, thus leading to understand that the Romans were aware of the link between fire and water in the Colli Albani region and that it was possible to find both in the lake, where gas exhalation
was the product of the two elements.

Shoreline and shelf-edge trajectories describe the migration through time of sedimentary systems, using geomorphological breaks-in-slope that are associated with key changes in depositional processes and products. Analysis of these trajectories provides a simple descriptive tool that complements and extends conventional sequence stratigraphic methods and models. Trajectory analysis offers four advantages over a sequence stratigraphic interpretation based on systems tracts: (1) each genetically related advance or retreat of a shoreline or shelf edge is viewed in the context of a continuously evolving depositional system, rather than as several discrete systems tracts; (2) subtle changes in depositional response (e.g. within systems tracts) can be identified and honoured; (3) trajectory analysis does not anticipate the succession of depositional events implied by systems-tract models; and (4) the descriptive emphasis of trajectory analysis does not involve any a priori assumptions about the type or nature of the mechanisms that drive sequence development. These four points allow the level of detail in a trajectory-based interpretation to be directly tailored to the available data, such that the interpretation may be qualitative or quantitative in two or three dimensions. Four classes of shoreline trajectory are recognized: ascending regressive, descending regressive, transgressive and stationary (i.e. nonmigratory). Ascending regressive and high-angle (accretionary) transgressive trajectories are associated with expanded facies belt thicknesses, the absence of laterally extensive erosional surfaces, and relatively high preservation of the shoreline depositional system. In contrast, descending regressive and low-angle (nonaccretionary) transgressive trajectories are associated with foreshortened and/or missing facies belts, the presence of laterally extensive erosional surfaces, and relatively low preservation of the shoreline depositional system. Stationary trajectories record shorelines positioned at a steeply sloping shelf edge, with accompanying bypass of sediment to the basin floor. Shelf-edge trajectories represent larger spatial and temporal scales than shoreline trajectories, and they can be subdivided into ascending, descending and stationary (i.e. nonmigratory) classes. Ascending trajectories are associated with a relatively large number and thickness of shoreline tongues (parasequences), the absence of laterally extensive erosional surfaces on the shelf, and relatively low sediment supply to the basin floor. Descending trajectories are associated with a few, thin shoreline tongues, the presence of laterally extensive erosional surfaces on the shelf, and high sediment supply to basin-floor fan systems. Stationary trajectories record near-total bypass of sediment across the shelf and mass transfer to the basin floor.

Gerhard Bosinski, Martin Street & Michael Baales (eds., 1995): The Palaeolithic and Mesolithic of the Rhineland. In: Wolfgang Schirmer (ed.): Quaternary field trips in Central Europe. 14th int. INQUA-Congress Berlin 1995. Vol. 2. München, 829-999.

Überblick zum Paläolithikum und Mesolithikum (mit kurzen Fundstellenbeschreibungen) aus dem Rheinland, d.h. vom Hochrhein (Baden und Elsass-Lothringen) bis zum Niederrhein einschließlich der angrenzenden Mittelgebirgslandschaften.

Overview on important Palaeolithic to Mesolithic sites in the "Rhineland" - from the Upper Rhine valley of SE France and Baden to the Lower Rhine Embayment with adjacent upland Areas.

A new category of large-scale volcanism, here termed Snake River (SR)-type volcanism, is defined with reference to a distinctive volcanic facies association displayed by Miocene rocks in the central Snake River Plain area of southern Idaho and northern Nevada, USA. The facies association contrasts with those typical of silicic volcanism elsewhere and records unusual, voluminous and particularly environmentally devastating styles of eruption that remain poorly understood. It includes: (1) large-volume, lithic-poor rhyolitic ignimbrites with scarce pumice lapilli; (2) extensive, parallel-laminated, medium to coarse-grained ashfall deposits with large cuspate shards, crystals and a paucity of pumice lapilli; many are fused to black vitrophyre; (3) unusually extensive, large-volume rhyolite lavas; (4) unusually intense welding, rheomorphism, and widespread development of lava-like facies in the ignimbrites; (5) extensive, fines-rich ash deposits with abundant ash aggregates (pellets and accretionary lapilli); (6) the ashfall layers and ignimbrites contain abundant clasts of dense obsidian and vitrophyre; (7) a bimodal association between the rhyolitic rocks and numerous, coalescing low-profile basalt lava shields; and (8) widespread evidence of emplacement in lacustrine-alluvial environments, as revealed by intercalated lake sediments, ignimbrite peperites, rhyolitic and basaltic hyaloclastites, basalt pillow-lava deltas, rhyolitic and basaltic phreatomagmatic tuffs, alluvial sands and palaeosols. Many rhyolitic eruptions were high mass-flux, large volume and explosive (VEI 6–8), and involved H2O-poor, low-δ18O, metaluminous rhyolite magmas with unusually low viscosities, partly due to high magmatic temperatures (900–1,050°C). SR-type volcanism contrasts with silicic volcanism at many other volcanic fields, where the fall deposits are typically Plinian with pumice lapilli, the ignimbrites are low to medium grade (non-welded to eutaxitic) with abundant pumice lapilli or fiamme, and the rhyolite extrusions are small volume silicic domes and coulées. SR-type volcanism seems to have occurred at numerous times in Earth history, because elements of the facies association occur within some other volcanic fields, including Trans-Pecos Texas, Etendeka-Paraná, Lebombo, the English Lake District, the Proterozoic Keewanawan volcanics of Minnesota and the Yardea Dacite of Australia.

The recent discovery of the direct link between Deccan volcanism and the end-Cretaceous mass extinction also links volcanism to the late Maastrichtian rapid global warming, high environmental stress, and the delayed recovery in the early Danian. In comparison, three decades of research on the Chicxulub impact have failed to account for long-term climatic and environmental changes or prove a coincidence with the mass extinction. A review of Deccan volcanism and the best age estimate for the Chicxulub impact provides a new perspective on the causes for the end- Cretaceous mass extinction and supports an integrated Deccan-Chicxulub scenario. This scenario takes into consideration climate warming and cooling, sea-level changes, erosion, weathering,ocean acidification, high-stress environments with opportunistic species blooms, the mass extinction, and delayed postextinction recovery.
The crisis began in C29r (upper CF2 to lower CF1) with rapid global warming of 4 °C in the oceans and 8 °C on land, commonly attributed to Deccan phase 2 eruptions. The Chicxulub impact occurred during this warm event (about 100–150 k.y. before the mass extinction) based on the stratigraphically oldest impact spherule layer in NE Mexico, Texas, and Yucatan crater core Yaxcopoil-1. It likely exacerbated
climate warming and may have intensifi ed Deccan eruptions. The reworked spherule layers at the base of the sandstone complex in NE Mexico and Texas were deposited in the upper half of CF1, ~50–80 k.y. before the Cretaceous-Tertiary
(K-T) boundary. This sandstone complex, commonly interpreted as impact tsunami deposits of K-T boundary age, was deposited during climate cooling, low sea level, and intensified currents, leading to erosion of nearshore areas (including Chicxulub
impact spherules), transport, and redeposition via submarine channels into deeper waters. Renewed climate warming during the last ~50 k.y. of the Maastrichtian correlates
with at least four rapid, massive volcanic eruptions known as the longest lava flows on Earth that ended with the mass extinction, probably due to runaway effects. The kill mechanism was likely ocean acidifi cation resulting in the carbonate
crisis commonly considered to be the primary cause for four of the five Phanerozoic mass extinctions.

Age and rock type, regional distribution and structural setting of volcanic and plutonic manifestations from the western Mediterranean basin and peripheral orogens during the past 30 Ma are examined. Distinct magmatic phases (which range tentatively between 30 and 15, 15 and 9, 8 and 6, 5 and 2, 2 and 1.5, and finally between 1.5 and 0 Ma) exhibit a large variety of rock types which reflect complex processes of
backarc and arc extension related with convergence between the European and the African–Ionian–Adriatic plates. The overall length of a complex plate boundary zone increased with time from ca. 1400 to 2500 km along-strike. Widespread, extension-related orogenic products were emplaced subsequent to distinct convergent processes which led to formation of the Hercynian, Alpine and Apenninic orogens.
Attenuation of the ‘Alpine’ area was initiated with eruption of plutonic and volcanic rocks of acidic calcalkaline
composition and of volcanics of tholeiitic (subalkaline) affinity. Tholeiites were probably linked to faster rates of intra-orogenic extension reaching the stage of oceanic opening in the south Tyrrhenian sea. In addition, localized small-volume eruptions of ultrapotassic rocks (lamproites) accompanied thinning
and stretching of the Alpine orogenic wedge. Intraplate Na-alkaline manifestations are widespread in the passive margins and in foreland areas. Overall, the episodic progression of magmatic activity in the western Mediterranean reflects complex geodynamic processes of retreating subduction, spreading and crustal attenuation which were preceded in time by continent-continent collision in the entire area. # 2002
Elsevier Science Ltd. All rights reserved.

A simple filter is developed which transforms VLF-EM real magnetic field transfer functions into apparent resistivities. It is based on the relationship between the horizontal derivative of the surface electric field and the vertical magnetic field at the surface of a two-dimensional earth model. The performance of this simple autoregressive filter is tested for modelled and real survey data. The technique yields profiles of apparent resistivity very similar, both in magnitude and in wavelength, to those which would have been obtained using VLF-EM resistivity measurements or d.c. resistivity profiling. This low-pass filter has the advantage of reducing high-wavenumber noise in the data; therefore only the major features of the VLF-EM profile are displayed.

В статье рассматривается роль и значимость импактных событий в активизации геотектонических процессов и их место в современной теории тектоники плит. Приводится краткий обзор и история развития современной геотектонической теории, указываются новые предполагаемые причинно-следственные процессы в описываемых событиях.

Περίληψη:
Η παρούσα προπτυχιακή διπλωµατική εργασία µε τίτλο «ΣΥΓΚΡΙΤΙΚΗ ΜΕΛΕΤΗ ΕΠΙΛΕΓΜΕΝΩΝ ΓΕΩΛΟΓΙΚΩΝ ∆Ι∆ΑΚΤΙΚΩΝ ΕΓΧΕΙΡΙ∆ΙΩΝ: ΗΦΑΙΣΤΕΙΟΤΗΤΑ ΚΑΙ ΘΕΡΜΟΤΗΤΑ ΣΤΟ ΕΣΩΤΕΡΙΚΟ ΤΗΣ ΓΗΣ», έχει ως σκοπό την ανάλυση και µελέτη γεωλογικών διδακτικών εγχειριδίων - καταρχάς γενικότερα στο σύνολό τους και έπειτα ειδικότερα όσον αφορά την ηφαιστειότητα και θερµότητα στο εσωτερικό της γης - στηριζόµενοι στην µεθοδολογία των Μαρία ∆ρακοπούλου, Κωνσταντίνου Σκορδούλη και Κρυσταλλία Χαλκιά όπως προτάθηκε στο έργο τους «Ανάλυση στοιχείων ιστορίας της επιστήµης στα σχολικά εγχειρίδια φυσικής της πρωτοβάθµιας εκπαίδευσης κατά τον «20ο αιώνα», τροποποιηµένη και παραµετροποιηµένη όπου κρίνεται σκόπιµο ώστε να µεγιστοποιείται το όφελος από την χρήση τους.

ABSTRACT:
In this particular thesis which is entitled as “COMPERATIVE STUDY OF SELECTED GEOLOGICAL TEXTBOOKS: VOLCANISM AND HEAT INSIDE EARTH”, the aiming goal is analyzing and studying selected textbooks of geology - first generally in total and then especially in volcanism and heat inside earth - based to methology of Maria Drakopoulou, Constantinos Skordoulis and Crystallia Chalkia as referenced in “Critical Analysis of School Science Textbooks” and configured to meet the requirements of geological science.

The numerical multilayered mapping at 1/50 000 of the area of activity of the Cap-Vert to the west of the
16°40’W meridian, provides Senegal with her first geological maps at this scale. The multilayered mapping
fully developed on the Geographical Information System (GIS) presents layers of topography, substratum
geology, geology of cover formations, aquifers hydrogeology, aquifer potential, piezometry,
hydrogeochemistry, aquifer vulnerability, underground invasion by brackish waters, listing of mines and
quarries, mineral resources’ potential and ground occupation.
The numerical multilayered mapping at 1/20 000 of the Cap-Vert peninsula, to the west of the 17°10’W
meridian, updates the geological maps by Elouard, Hébrard et al. (1976). However, the new dispensation
proposes different maps for the solid geology and for the soft cover. Additional layers concern: aquifer
contamination by nitrates and pesticides, susceptibility to the phenomena of swelling and shrinking soils, and
geotechnical ability.
Observation points from archives, boreholes and field operations have been stored in the GIS, where they
can easily be consulted along with the relevant information, documentation, sketches and pictures. The GIS
is a dynamic, interactive tool with its layers ready for continuous updating.
Geometrical modelling of the volcanic and sedimentary formations reveals an unsuspected dense faulting
system on the eastern side of the peninsula.
Present building above potentially risky areas, on the western coast of the peninsula, is bound to draw a
renewed attention to geotechnics in the foreseeable future.

This short communication aims at providing an updated report on degassing activity and ground deformation variations observed during the ongoing (2012-2019) Campi Flegrei caldera unrest, with a particular focus on Pisciarelli, currently its most active fumarolic field. We show that the CO 2 flux from the main Pisciarelli fu-marolic vent (referred as "Soffione") has increased by a factor > 3 since 2012, reaching in 2018-2019 levels (>600 tons/day) that are comparable to those typical of a medium-sized erupting arc volcano. A substantial widening of the degassing vents and bubbling pools, and a further increase in CO 2 concentrations in ambient air (up to 6000 ppm), have also been detected since mid-2018. We interpret this escalating CO 2 degassing activity using a multidisciplinary dataset that includes thermodynamically estimated pressures for the source hydrothermal system, seismic and ground deformation data. From this analysis, we show that degassing, deformation and seismicity have all reached in 2018-2019 levels never observed since the onset of the unrest in 2005, with an overall uplift of ~57 cm and ~448 seismic events in the last year. The calculated pressure of the Campi Flegrei hydrothermal system has reached ~44 bar and is rapidly increasing. Our results raise concern on the possible evolution of the Campi Flegrei unrest and reinforce the need for careful monitoring of the de-gassing activity at Pisciarelli, hopefully with the deployment of additional permanent gas monitoring units.