The Tyrrhenian back－arc basin and subduction of the Ionian lithosphere

A deep, narrow, and distorted Benioff zone, plunging from the Ionian Sea towards the southern Tyrrhenian basin, is the remnant of a long and eastward migrating subduction of eastern Mediterranean lithosphere. From Oligocene to Recent, subduction generated the Western Mediterranean and the Tyrrhenian back-arc basins, as well as an accretionary wedge constituting the SouthernAoenninic Arc.In the Tyrrhenian Sea, stretching started in late Miocene and eventually produced two small oceanic areas: the Vavilov Plain during Pliocene (in the centralsector) and the Marsili Plain during Quaternary (in the southeastern sector). They are separated by a thicker crustal sector, called the Issel Bridge. Back-arc exten-sion was rapid and discontinuous, and affected a land locked area where continental elements of various sizesoccurred. Discontinuities in extension were mirrored bychanges in nature of the lithosphere scraped off to form the Southern Apenninic Arc. Part of the tectonic units of the southern Apennines, accreted into the wedge from late Miocene to Pliocene, had originally been laid down on thinned conti-nental lithosphere, which should constitute the deep portion of the present slab. After Plio-cene, only Ionian oceanic lithosphere wassubducted, because the large buoyancy of thewide and not thinned continental lithosphere of Apulia and Africa (Sicily) preserved the seelements from roll back of subduction. After Pliocene, the passively retreating oceanic slabhad to adjust and distort according to the geometry of these continental elements.The late onset of arc volcanism in respect to the duration of extension in the Tyrrhenian-Ionian system may find an expla-nation considering an initial stage of subduc-tion of thinned continental lithosphere. The strong Pleistocene vertical movements that occurred in the whole southeastern system(subsidence in the back-arc basin and upliftin the orogenic arc) may instead be related to the distortion of the oceanic slab.     

The Lagoon of Venice： geological setting,evolution and land subsidence

The paper deals with the geological setting, history and subsidence of the Venetian Plain. Major attention is paid to the Pleistocene-Holocene stratigraphic sequence in the Lagoon of Venice, in relation to its origin that datesback to 6-7 kyr BP. Geological land subsidence, which played an important role in the origin and the evolution of the lagoon, and anthropogenic subsidence, that has recently assumed a major importance for the Venetian environment, are discussed. Considering also the sealevel rise, 23 cm loss in land elevation has occurred in the last century, leading to increased flooding events and environmental problems that require protective works.     

Earthquakes in Italy： past, present and future

Italy has a long-standing tradition of earthquake investi-gations. Seismologists can rely on one of the longest and most detailed records of historical seismic#y, 20 years of homogeneous and reliable instrumental data, systematic and widespread active stress data and a comprehensive database of potential seismogenic sources. Here wed escribe these datasets and discuss how they may help usanticipate the large earthquakes of the future.     

Geology and health：closing the gap

It was discovered several decades ago that the natural geo-environment could substantially impact on the health of animals and humans. However, despite the growth of evidence supporting this discovery, there has not been a close interaction between geoscientists and health scientists in assessing the need to study the various facets of the relationships between human and animal health and air, water, soils and rocks. This book is timely in closing that gap as stated in its title.     

Jurassic--climate and biodiversity： The 6th International IGCP 506 Symposium

August was an intense and busy month for many geologists as the large 33rd IGC meeting was held in Oslo, Norway, from 6 to 14 August. Over 6,000 scientists from 113 countries contributed talks, posters and discussions at the IGC on a broad range of geo- logical topics. The congress was preceded and followed by as many as 30 fieldtrips coveting Scandinavian geology.     

The large-wavelength deformations of the lithosphere： materials for a history of the evolution of thought from the earliest times to plate tectonics

The notable authority on tectonics and the history of geosciences, Professor Celal Sengor from Istanbul, has produced another remarkable book-which, as he tells the reader, grew rapidly from an initial paper into a massive tome. Just as Georges Cuvier liked the idea of ‘bursting the limits of time‘, so Professor Sengor has again ‘burst the limits of a paper‘!     

Geological features of Larderello－Travale and Mt.Amiata geothermal areas （southern Tuscany, Italy）

This paper summarises the geological features of the Larderello-Travale and Monte Amiata areas, where the world‘s most ancient exploited geothermal fields are located. In both geothermal areas, three regional tectonostratigraphic elements are distinguished, from the top: (a) Late Miocene-Pliocene and Quaternary,continental to marine sediments; (b) the Ligurian and Sub-Ligurian complexes, which include remnants of the Jurassic oceanic realm and of the transitional area to the Adriatic margin, respectively; (c) the Tuscan Unit(Tuscan Nappe), composed of sedimentary rocks rang-ing in age from Late Triassic to Early Miocene. The sub-stratum of the Larderello and Monte Amiata areas isreferred to as the Tuscan Metamorphic Complex. This ismainly known through drilling of geothermal wells. This complex is composed of two metamorohic units: the upper Monticiano-Roccastrada Unit and the lower Gneiss Complex. The Monticiano-Roccastrada Unit consists of(from top to bottom): the Verrucano Group,the Phyllite-Quartzite Group and the Micaschist Group.The Gneiss Complex consists only of pre-Alpine poly-metamorphic gneiss. The Tuscan Metamorphic Complexis affected by contact metamorphism by Plio-Quater-nary granitoids and their dy ke swarms. Hydrothermal phenomena still occur in both geothermal fields. The Larderello-Travale and Mt. Amiata geothermal fields are located in the inner Northern Apennines, in an area that has been subject to extension since the ?Early-Mid-dle Miocene. Two main extensional events are well expressed in the structures of the geothermal areas. The first extensional event (?Early-Middle Miocene) deter-mined the tectonic delamination of the Ligurian Units and Tuscan Nappe. The second extensional event (LateMiocene-Present) is characterized by high-angle nor-mal faults bounding the Neogene tectonic depressions of southern Tuscany.     

The basement complexes in Italy, with special regards to those exposed in the Alps： a review

Most of the sedimentary rocks occurring in Italy are post-Carboniferous. All what lies below is considered basement, mostly metamorphic or igneous. Understand-ing the pre-Carboniferous evolution depends on the reconstruction of the sedimentary, metamorphic and igneous evolution of the basement. In general, the base-ment sedimentary protoliths were Lower to Middle Pale-ozoic siliciclastic rocks, while the igneous protolithsbelong to an Ordovician cycle. The prevailing metamor-phism,from very-low grade to granulite facies, is Variscan. It was followed by the formation of large amounts of granitic melts.     

Four centuries of geological travel： The search for knowledge on foot, bicycle, sledge and camel

The greater ease of travel in the twentieth century led Raymond Priestley, geologist to Ernest Shackleton＇s 1907-1909 Antarctic expedition, in discussing a University of Melbourne geology excursion to the gold mining area of Daylesford in September 1937, to record： ＂the new method of doing geology with a motor bus while very efficient is not as energetic as the old. It is true we see as much in a day as we used to see in the old days in a week,     

Crustal thickening in an active margin setting （Philippines）： The whys and the hows

A synthesis of crustal thickness estimates was made recently utilizing available field, geochemical, seismicity, shear wave velocity and gravity data in the Philippines. The results show that a significant portion of the Philippine archipelago is generally characterized by crust with a thickness of around 25 to 30 kilometers. However, two zones, which are made up of a thicker crust (from 30 to 65 km) have also been delineated. The Luzon Central Cordillera region is characterized by thick crust. Another belt of thickened crust is observed in the Bicol-Negros-Panay-Central Mindanao region. This paper examines the interplay of tectonic and magmatic processes and their role in modifying Philippine arc crust. The processes, which could account for the observed crustal thicknesses, are presented. The contributions of magmatic arcs as compared to the contribution of the emplacement and accretion of ophiolite complexes to crustal thickness are also discussed.