Sách Updates in volcanology – a comprehensive approach to volcanological problems - Edited by Francesco S

Multiscale Seismic Tomography Imaging of Volcanic Complexes

Updates in Volcanology – A Comprehensive Approach to Volcanological Problems
Edited by Francesco Stoppa

Contents
Preface IX
Part 1 Field Methods in Volcanology 1
Chapter 1 Hydrovolcanic vs Magmatic Processes in Forming Maars and
Associated Pyroclasts: The Calatrava -Spain- Case History 3
F. Stoppa, G. Rosatelli, M. Schiazza and A. Tranquilli
Chapter 2 An Overview of the Monogenetic Volcanic Fields of
the Western Pannonian Basin: Their Field Characteristics and
Outlook for Future Research from a Global Perspective 27
Károly Németh
Chapter 3 Quaternary Volcanism Along
the Volcanic Front in Northeast Japan 53
Koji Umeda and Masao Ban
Part 2 Large Igneous Provinces 71
Chapter 4 Origin, Distribution and Evolution
of Plume Magmatism in East Antarctica 73
Nadezhda M. Sushchevskaya, Boris V. Belyatsky
and Anatoly A. Laiba
Chapter 5 Bimodal Volcano-Plutonic Complexes in the Frame of Eastern
Member of Mongol-Okhotsk Orogenic Belt, as a Proof
of the Time of Final Closure of Mongol-Okhotsk Basin 99
I. M. Derbeko
Chapter 6 Hotspot Concept: The French Polynesia Complexity 125
Claudia Adam
Chapter 7 Magmatectonic Zonation of Italy:
A Tool to Understanding Mediterranean Geodynamics 153
Giusy Lavecchia and Keith Bell
Part 3 Applied Volcanology 179
Chapter 8 Identification of Paleo-Volcanic
Rocks on Seismic Data 181
Sabine Klarner and Olaf Klarner
Chapter 9 Multiscale Seismic Tomography
Imaging of Volcanic Complexes 207
Ivan Koulakov


Preface
Volcanism witnesses every major change of our planet and other planets.
In Advances in Volcanology, scientists from highly active volcanic countries, such as
Japan, Italy, and New Zealand, as well as others from Germany, Portugal, and Russia,
debate less commonplace themes. Topics from classic field volcanology, including
practical problems with volcanic stratigraphy in oil exploitation, to the most modern
techniques related to tomographic studies are discussed. The question about the role
of hydro-volcanism as a modifying factor versus juvenile gases as the primary engine
of volcanism is discussed in full. The complex geodynamic meaning of the large
basaltic province versus large alkaline provinces is analyzed by means of large scale
examples, using geochemical, tectonic, and stratigraphic demonstrations. Tectonic
modification related to collisional-extensional volcanic environments, which puzzle
structural geologists, is also considered. This is germane to a modern conception of
volcanology as a typical multi-scale, multi-method discipline.
Field methods in volcanology
Chapter 1 by Stoppa, Rosatelli, Schiazza, and Tranquilli, and chapter 2 by Németh
provide excellent examples to understand the volcanic facies and the distribution of
monogenetic volcanoes that cluster in intra-continental settings. Large monogenetic
volcanic fields in western Hungary and central Spain are presented in detail with the
aim of characterizing their pyroclastic successions and chemistry, and inferring their
eruptive mechanisms. In Chapter 3, Umeda and Ban provide a compilation of the
distribution of 139 volcanic centres depicting eruption style, magma compositions, and
eruptive volume related to change from the condition of a neutral stress regime with low
crustal strain rate to compression along major thrust faults associated with uplift in a
volcanic front. It is widely assumed that magma cannot rise so easily in compressional
settings, and the distribution of volcanic centres is controlled mostly by local extensional
dislocations and gravitational instability. However, in this chapter, the reason why an
increase in erupted magma volume may be related to the subduction rate and to the
lowering of differential stress by thermal effects is discussed.
Large igneous provinces
Volcanism is spread and distributed well at the surface of the Earth in the form of
large plumes that last for long geological periods, affecting big areas. For several years,
this concept has been debated, and the existence of the plumes themselves is
questioned. Thus, the following chapters are devoted to this problem.
In Chapter 4, Sushchevskaya, Belyatsky, and Laiba show that remote volcanic
provinces, which are interpreted as the manifestation of the Karoo–Maud plume in
Antarctica and Africa, have a considerable duration and multistage character.
Derbeko, in chapter 5, depicts the bimodal petrochemical series of the Mongol-
Okhotsk orogenic belt in the interval 119 – 97 Ma. The mantle source composition is
characterized by trace element enrichment/depletion in terms of LILE/HFSE ratios and
related to their tectonic position. Adam, in Chapter 6, and Lavecchia and Bell, in
Chapter 7, consider a large-scale analysis of regional geochemistry, volcanology, and
tectonics of famous igneous provinces, such as those of the Mediterranean and French
Polynesia regions, which is discussed in a broad comparative analysis that brings us
back to the mystery of the planet dynamics. French Polynesia is characterized by a
great concentration of volcanism on the South Pacific Superswell. The description of
this area provides a fairly accurate image of the mantle underneath this region,
demonstrating that a direct link exists between the mantle convection and the surface
observation, and can bring new insight to the plume debate. In Chapter 7, Lavecchia
and Bell take inspiration from the Mediterranean potassic series paradoxes, due to a
peculiar coexistence, sometimes within the same location and at the same age, of SiO2-
oversaturated rock-types (calcalkaline to high-K calcalkaline products and, more
rarely, leucite-free lamproites) and of SiO2-undersaturated potassic to ultra-potassic
rock-types (leucite-phonolites to leucitites, melilitites, and kamafugites) and Na-rich
series. Strangely enough, volcanic products, although clearly belonging to the same
magmatotectonic domain, the Mediterranean wide-rift basin, are attributed in the
literature to contrasting geodynamic environments. The first of these being anorogenic
and intra-plate, and the second being orogenic and subduction-related. The discussion
mainly concerns the nature of the metasomatic component, which might result from
pressure-related dehydration of the subducting slabs, or from upwelled deep mantle
components. When not a priori forced to fit all the available multidisciplinary source
elements within a subduction view, other interesting scenarios can be opened, which
also allows a unifying interpretation of the overall Mediterranean and peri-
Mediterranean magmatism.
Applied volcanology
Chapter 8 by Klarner and Klarner makes us aware of the role of pyroclastics and
epiclastics when exploring hydrocarbon reservoirs. These rocks may produce practical
problems, due to complex diagenetic overprints and lateral seals or migration barriers,
which produce both positive and negative impacts on the petroleum system. It is
therefore essential to understand the distribution of volcanics in the vicinity of the
reservoir. In Chapter 9, Koulakov demonstrates the capacity of tomographic methods
for studying magma sources in different areas of volcanic provinces at different scales.
Tomographic data are considered in a multidisciplinary context together with
geological, geophysical, and geochemical data.
All the authors stress that modern volcanology is a young science, but the interest in
volcanoes is perhaps as old as human beings. It is thus necessary to place the
arguments presented in this book in a historical light, which will help readers to
understand the basis of many volcanological arguments.
A fundamental step in volcanological history was the eruption of Vesuvius in 79 AD.
Mount Vesuvius became active after a secular resting, and it destroyed Pompeii and
other neighbouring towns. Pliny the Elder (c. 23 AD – 79 AD), led primarily by his
curiosity for natural history, tried to get close to the volcano, but lost his life during the
final phase of the eruption. However, his nephew Pliny the Younger (c. 61–114 AD)
provided the first direct accurate description of a volcanic eruption. Paradoxically, this
eruption, which marks the maximum advance of knowledge of volcanoes, was the last
opportunity for the discussion of these topics before the medieval stagnation. For two
millennia, scientists continued to place emphasis on the lava effusions, neglecting the
explosive processes. The resumption of studies in volcanology ideally coincided with
the formation of Monte Nuovo (1538) in the Phlegraean Fields. Although a relatively
small-scale eruption, it brought into question almost all of the medieval dogmas on the
creation of the Earth. The eruption of Vesuvius in 1631 came after centuries of
stagnation, and prompted European scientists to come to the first formulation of the
modern geological theories. From that point on until the beginning of 1900, Vesuvius,
with its continuous activity and its proximity to the city of Naples, a capital of arts and
culture, was considered the prototype of all volcanoes. Aristotle said that man,
because of his limited perception of the flow of events, erroneously attributes to
disasters and the power to change the course of nature, when in fact, they are part of a
constantly changing Earth (Meteorologica, Book II). Catastrophism, the theory
adopted by Christianity, dominated Western countries’ thinking for many centuries.
Extreme isolation and harsh living conditions prevented visits by scholars or the birth
of scientific schools in areas outside of an active volcanic continental Europe. For these
reasons, the current dispute between the various scientific communities continued,
until recently, to be based on an unrepresentative number of more strategically placed
volcanoes, such as Vesuvius.
With Newton’s influence, the focus slowly shifted to the idea of a planet resulting
from the balance of constantly active forces. During the eighteenth century, the
dispute between Neptunists and Plutonists offered the opportunity to break the
deadlock that was already present in Aristotle's thoughts concerning the dichotomy
between fire (central heat, actualistic, and evolutionary vision of the earth) and water
(diluvian vision, catastrophic, and "chemical” volcanism). The sudden formation of
Ferdinandea Island, in the Strait of Sicily in 1831, dispelled the last doubts about the
nature of the volcanic phenomena. For these reasons, Italy is considered the cradle of
volcanology.
The geologists of the nineteenth century had a clearer view of the fact that volcanism
was not randomly distributed or conditioned by local phenomena. However, this view
of the global distribution of volcanism was not aware of the existence of volcanic mid
ocean ridges and African rift volcanoes, which were still very poorly understood.
Substantial progress has occurred in our century. The vision of volcanism is now
framed in the global tectonic theory, although not always completely circumscribed by
a lithosphere formed of plates. Some eruptions have been of great importance for the
impetus given to the progress of volcanological studies: the eruptions of Krakatau in
the Sunda Strait in 1883, Mount Pelée in Martinique in 1902, Bezimianny Kamchakta in
1956, and St Helens in the Cascades Range in 1980.
Nowadays, volcanology is trying to escape from the extreme fragmentation and
specialization that has occurred in recent years. It is rapidly gaining renewed interest
among geologists and geophysicists. Its global significance becomes clearer when one
tries to tackle the open questions that geology still poses. It is understood that only
comprehensive and comparative study of large volcanic provinces and their
peculiarities can form a consistent picture of the dynamics of the planet. Advances in
Volcanology is a good opportunity to open our minds about volcanoes and the
problems with their interpretation in a multicultural world-wide approach.
Prof. Francesco Stoppa
Earth Sciences Department, Gabriele d'Annunzio University, Chieti,
Italy