Abstract Public health, the protection of the health of populations through community engagement, is a modern specialty originating in post-Industrial Revolution Britain, while environmental geochemistry is of even more recent origin. The influence of geology on health was first recognized in Classical times, although it was later supplanted by the miasma theory of disease. During the Renaissance, medical teaching began to concentrate more on diagnosis and treatment of the sick individual and less on preserving the health of populations. The concept of geology as a determinant of health re-emerged with the growth of scientific knowledge during the Enlightenment period of the eighteenth century. The nineteenth century saw the first identification of trace element deficiency disease and the publication of a textbook of public health which described geological influences on health. Over the next 100 years both public health and environmental geochemistry became established on a firm footing, although as separate disciplines. Recently the public health focus has been on lifestyle choices, but environmental geochemistry remains a potentially powerful partner in the fight to protect health, and there is much scope to enhance collaborative working. The legacy of the pioneers of both public health and geology must not be forgotten.

Abstract The Bosphorus (Istanbul) Strait is a natural strait that connects the Black Sea with the Aegean Sea via the Sea of Marmara and the Dardanelles Strait. It is a 31 km-long and 3.5 km-wide winding channel, with an irregular bottom morphology. It has depressions up to 110 m deep, and two sills with depths of 35 and 58 m in the south and north, respectively. Presently, a two-layer water exchange exists through the strait, with the Mediterranean and Black Sea waters forming the lower and upper layers, respectively. The Bosphorus channel extends as shelf valleys on the Black Sea and Sea of Marmara shelves. However, it operated as a river valley or an estuary during the stadial lowstand periods. The infill sedimentary succession of the Bosphorus channel is up to 100 m thick above the Paleozoic–Cretaceous basement with an irregular topography. The oldest sediments are sandy to muddy fluvial–lacustrine facies of late Pleistocene age, which are preserved only in up to 160 m-deep scoured depressions of the basement. They are overlain by mid–late Holocene estuarine–marine shelly sandy to muddy sediments with patches of bioherms and shelly lag deposits. The Bosphorus outlet areas of the Black Sea and Sea of Marmara are characterized by a submarine fan and a shelf valley, respectively. The fan system in the Black Sea started depositing c. 900 years after the initial vigorous marine water incursion at c. 8.4 14 C ka BP. On the Marmara shelf, extension of the Bosphorus channel is a sinuous shelf valley with a channel–levee complex that was deposited by the Black Sea outflow during 11–10 14 C ka BP. Catastrophic floodings of the Sea of Marmara by torrential Black Sea outflows during the Greenland Interstadial melt-water pulses, as well as the strong Mediterranean current towards the Black Sea during the interglacial periods, were responsible for carving out the Bosphorus channel and the shelf valleys, as well as removing the sediments belonging to the earlier periods.

Abstract The well-known Cenozoic Aegean extensional regime, initiated at c. 25 Ma, thinned the crust so that most of it now lies submerged. North of the western continuation of the North Anatolian Fault the Aegean extensional regime is present in central and southern Bulgaria, northern Greece, Former Yugoslavian Republic (FYR) of Macedonia and eastern Albania. Here the system is exposed on land and offers an opportunity to reconstruct the extensional evolution of the system. The southern Balkan peninsula forms the northern part of the Aegean extensional system; deformation is not as great as in the Aegean, but reconstruction of this part of the extensional regime will provide important constraints on its dynamics. Following a period of arc-normal extension associated with Late Eocene-Late Oligocene magmatism, major lithospheric extension appears have begun between 26 and 21 Ma in northern Greece, involving east-northeast-west-southwest extension east of Mount Olympos, on the Island of Thasos and near Kavala. This period of extension may have been accompanied by a short period of coeval compression north of the arc during Early Miocene time or perhaps a little earlier in the Thrace Basin of northwestern Turkey. Northeast-southwest directed Middle-Late Miocene extension appears to have developed obliquely to the older magmatic arc and migrated northward into southwestern Bulgaria in the Sandanski Graben (and perhaps also into the Mesta and Padesh Grabens) by 16.3–13.6 Ma, and in the Blagoevgrad and Djerman Grabens by c. 9 Ma. Extension in south-western Bulgaria was reorganized by c. 5 Ma and in northern Greece extension on the Strymon Valley detachment fault ended by c. 3.5 Ma, but extension continued on new fault systems. From limited structural and stratigraphic data, it is speculated here that related extension may have also occurred during this time in FYR Macedonia and eastern Albania. This northeast-southwest extension is interpreted to be related to trench roll-back along the northern part of the subduction boundary in the western Hellenides. North-south extension along east-west striking faults in central Bulgaria began only after extension was well underway in northern Greece and the Sandanski Graben of south-western Bulgaria. Within the Sofia Graben, the Sub-Balkan grabens, and grabens to their east, north-south extension began at c. 9 Ma, and may have begun about the same time in the Plovdiv, Zagore and Tundja Grabens of the northern Thracian Basin: north-south extension has continued to the present in these grabens. The cause of the north-south extension is unclear and may be related to trench roll-back along the central part of the subduction zone in the Hellenides, or more local causes of clockwise and counterclockwise rotation of the western Hellenides and western Turkey, respectively. By Late Pliocene time a major erosion surface, the sub-Quaternary surface, was developed over a large area of central Bulgaria creating a major unconformity that marks the beginning of Quaternary deposition in the basinal areas. Many large and small graben-bounding faults in west-central Bulgaria displace this erosion surface and demonstrate the widespread extent of Quaternary north-south extension. North-south extension extended westward, with probably decreasing magnitude, across the older northwest trending graben of southwest Bulgaria (the Simitli and Djerman Grabens) and into eastern FYR Macedonia. During latest Pliocene(?) and Quaternary time, northern Greece developed a complex pattern of northeast-southwest extension associated with northeast to east-west striking right-lateral faults forming transfer faults between more local extensional areas. This system of faults overprinted the older northwest trending extensional faults, such as the Strymon Detachment, and may be related to the propagation of the right-lateral North Anatolian Fault into the north Aegean Sea and formation of parallel faults to its north. These two different tectonic regimes extend into FYR Macedonia, where a third regime of east-west extension in western FYR Macedonia and eastern Albania is present, and where extension may represent the continuation of the east-west extensional regime initiated in Middle-Late Miocene time. Active deformation determined from seismicity and Global Positioning System studies suggest northern Greece, and perhaps southwest Bulgaria and FYR Macedonia, is dominated by north-south extension. This pattern of deformation must have developed as recently as perhaps Late Quaternary time. Except for mountains near the Adriatic Sea all of the mountainous topography in the southern Balkan region may be the result of Miocene-Recent extension.

Abstract Late Miocene igneous rocks of Samos, in the southeastern Aegean Sea, comprise monzodiorite and minor granite of the Katavasis complex, trachyte and rhyolite of the Ambelos volcanic centre, and bimodal basalt–rhyolite at basin margins. Six new K–Ar ages, together with existing geochronology and biostratigraphy, show that the Katavasis complex and Ambelos centre date from 10–11 Ma and basalt–rhyolite from 8 Ma, correlating with cooling ages for the Katavasis complex and an unconformity in the basin fill. Monzodiorite, granite, trachyte and basalt all have similar radiogenic isotopes. Monzodiorite and basalt have similar trace element compositions and could result from 5–10% partial melting of enriched garnet lherzolite in the subcontinental lithosphere. Variations in trace elements suggest that trachyte and monzodiorite evolved by fractional crystallization from a parental magma similar to the younger basalt. The Katavasis and Ambelos rocks were synchronous with regional extension and listric faulting, which created opportunities for mid-crustal magma chambers and magma fractionation. Basalt extrusion was synchronous with the onset of north–south strike-slip faulting, which permitted more rapid transfer of magma to the surface. Late Miocene strike-slip faulting propagated from north to south in western Anatolia and the southeastern Aegean Sea, providing pathways for different types of mantle melts.

Over recent decades, numerous studies have highlighted the importance of opal, chalcedony and quartz varieties, chiefly in volcanic, but also in metamorphic and sedimentary environments. The focus is to define accurately their structures, composition and properties, as well as to identify the factors controlling the formation and the ageing of different forms of silica. In the field of archaeological sciences efficient discriminants are the bases from which the origin and provenance of materials may be traced. Substantial efforts were made in the attempt to combine geochemical, mineralogical, petrographic and geological features with archaeological and archaeometric information. However the results show that data integration is complicated, and several unanswered questions remain. On the one hand, archaeological research has focused on technological and ethnographic aspects, mainly concerning use-wear and heat-treatment studies. Mineralogical characterization has often been limited to the identification of the material, frequently by Raman microspectroscopy alone. On the other hand, the Earth sciences have provided basic mineralogical, crystal-chemical and geological knowledge, but failed to provide a systematic data collection of sources and their geochemistry. As a consequence, large gaps persist in the identification of archaeological opals, chalcedonies and quartz varieties, and in the geographic mapping of possible sources. In this context, the present review aims to summarize the current academic debate on such issues, possibly to encourage further work in the field. After a brief introduction to terminology, the structure of opals, their colours and properties are discussed, followed by an introduction to silica dissolution/precipitation and opal-formation processes. The next section reviews the information available on use of opals and provenance from historical sources, mainly Pliny the Elder, followed by a short list of ancient and modern opal supply areas, together with a (necessarily incomplete) summary of the geological and geochemical information. The discussion then encompasses chalcedony, agate and chalcedony varieties (carnelian, sard, onyx, sardonyx, chrysoprase, Cr-chalcedony, ‘gem silica’ or ‘chrysocolla chalcedony’ and heliotrope), following the same scheme as was adopted for opals. Terminology, distinguishing features, formation conditions, information derived from Pliny’s books, past and current supply areas and, finally, archaeometric provenance issues are addressed for each type of material. As for chalcedony, a comprehensive note on moganite has been included. The next section focuses on chert, flint and jasper. Given the large amount of materials available on this topic, the present review must necessarily be considered introductory and partial. The discussion aims to provide useful indications on how to distinguish chert from flint and chert from jasper; secondly, the information provided by Pliny and the archaeometric state of the art on these materials is reviewed. The last section examines quartz varieties: hyaline quartz (rock crystal), milky quartz, smoky quartz, rose and pink quartz, amethyst, citrine, prasiolite and blue quartz. An exhaustive mineralogical discussion on quartz is beyond the scope of this review; conversely a review of the historical information is provided, together with a brief list of major supply areas, a summary of the archaeometric studies performed on these materials, as well as an indication of the geological literature which can be used proficiently for provenance studies.