Extreme climate after massive eruption of Alaska's Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom.

The assassination of Julius Caesar in 44 BCE triggered a power struggle that ultimately ended the Roman Republic and, eventually, the Ptolemaic Kingdom, leading to the rise of the Roman Empire. Climate proxies and written documents indicate that this struggle occurred during a period of unusually inclement weather, famine, and disease in the Mediterranean region; historians have previously speculated that a large volcanic eruption of unknown origin was the most likely cause. Here we show using well-dated volcanic fallout records in six Arctic ice cores that one of the largest volcanic eruptions of the past 2,500 y occurred in early 43 BCE, with distinct geochemistry of tephra deposited during the event identifying the Okmok volcano in Alaska as the source. Climate proxy records show that 43 and 42 BCE were among the coldest years of recent millennia in the Northern Hemisphere at the start of one of the coldest decades. Earth system modeling suggests that radiative forcing from this massive, high-latitude eruption led to pronounced changes in hydroclimate, including seasonal temperatures in specific Mediterranean regions as much as 7 °C below normal during the 2 y period following the eruption and unusually wet conditions. While it is difficult to establish direct causal linkages to thinly documented historical events, the wet and very cold conditions from this massive eruption on the opposite side of Earth probably resulted in crop failures, famine, and disease, exacerbating social unrest and contributing to political realignments throughout the Mediterranean region at this critical juncture of Western civilization.

The Herculaneum victims of the 79 AD Vesuvius eruption: a review.

The scientific study of the victims of the 79 AD Vesuvius eruption began with the first discovery in the 1980s of hundreds of skeletons of people who had taken refuge in the suburban area of Herculaneum. Hundreds of human victims were found crowding the beach and a series of waterfront chambers, fixated into a final posture by the first of the deadly incoming pyroclastic currents. The towns of Herculaneum, Pompeii and other Roman settlements up to 20 kilometers away were suddenly hit and overwhelmed by successive ash-avalanches, fast moving clouds of hot volcanic ash and gases known as pyroclastic surges, capable of killing all residents who were not yet evacuated. Given the impossibility of access to the skeletal remains of the Pompeiians locked within the plaster casts and the sparse occasional finds of victims elsewhere, most of the anthropological studies focused on the victims discovered in Herculaneum. The first investigations were carried out to detect the biological and pathological features of these people. More recent multidisciplinary studies on the victims' skeletons and their volcanological context shed light on the dynamic impacts of the 79 AD Plinian eruption on the area around the volcano and on its inhabitants. The effects of the high temperatures of the surges as suffered by the remaining resident population were revealed, with crucial implications for the present-day risk of a similar outcome to around three million people living close to the volcano, including metropolitan Naples.

Dental fluorosis in the Vesuvius towns in AD 79: a multidisciplinary approach.

Background: Endemic fluorosis induced by high concentrations of fluoride in groundwater and soils is a major health problem in several countries, particularly in volcanic areas.Aim: To evaluate the occurrence of dental fluorosis resulting from exposure to high levels of environmental fluoride in 79 AD Herculaneum and close Vesuvius towns.Subjects and methods: The occurrence of dental fluorosis from teeth of the Herculaneum victims of the 79 AD eruption and some individuals from Pompeii (14-37 AD) and Nocera Inferiore (Salerno, IV sec. AD) was detected by means of Particle Induced Gamma-ray Emission technique (PIGE).Results: A clinical and analytical scenario of dental fluorosis resulted from the extreme high fluorine tooth content detected in teeth from Herculaneum and the Vesuvius area inhabitants. The adoption of PIGE technique has proved to be particularly effective in showing moderate as well as milder forms of dental fluorosis, otherwise not clearly detectable by clinical and histological analysis.Conclusions: Morphological, histological and elemental analysis of teeth of the 79 AD Herculaneum population show that in this area fluorosis occurred since Roman times.

First U-Pb zircon ages for late Miocene Ashfall Konservat-Lagerstätte and Grove Lake ashes from eastern Great Plains, USA.

This paper documents the first U-Pb zircon ages for Ashfall Fossil Beds (Nebraska, USA), a terrestrial Konservat-Lagerstätte mass-death assemblage that is arguably the most diverse of its type and age. The Ashfall tephra was correlated with ignimbrites from the Bruneau-Jarbidge volcanic field (12.7-10.5 Ma) in southwest Idaho based on geochemical analysis. The methods and geochemical data supporting the original age assessment of the ash bed, however, were never published, and there has been a persistent misconception that dateable heavy minerals (e.g., zircon) are absent. Notwithstanding, we recovered abundant zircons from Ashfall Fossil Beds, and from an ash bed ~6 km to the southeast at Grove Lake, Nebraska, and analyzed them through LA-ICP-MS. Our new zircon U-Pb age of 11.86 ± 0.13 Ma substantiates correlation of the Ashfall Fossil Beds deposit to tuffs originating from the Bruneau-Jarbidge caldera (~12.7-10.5 Ma). Our U-Pb zircon age of 6.42 ± 0.06 Ma for the Grove Lake ash bed coincides with supervolcanic activity in the Heise volcanic field (6.6-4.3 Ma) in eastern Idaho. These new dates improve age constraints of strata comprising the Ogallala Group and the important paleontological site. Moreover, we find that detrital and airfall zircons are unevenly distributed in the stratified ash beds we describe herein and presumably in similar deposits worldwide. Therefore, a higher-resolution sampling scheme is necessary in such cases.

A hypothesis of sudden body fluid vaporization in the 79 AD victims of Vesuvius.

In AD 79 the town of Herculaneum was suddenly hit and overwhelmed by volcanic ash-avalanches that killed all its remaining residents, as also occurred in Pompeii and other settlements as far as 20 kilometers from Vesuvius. New investigations on the victims' skeletons unearthed from the ash deposit filling 12 waterfront chambers have now revealed widespread preservation of atypical red and black mineral residues encrusting the bones, which also impregnate the ash filling the intracranial cavity and the ash-bed encasing the skeletons. Here we show the unique detection of large amounts of iron and iron oxides from such residues, as revealed by inductively coupled plasma mass spectrometry and Raman microspectroscopy, thought to be the final products of heme iron upon thermal decomposition. The extraordinarily rare preservation of significant putative evidence of hemoprotein thermal degradation from the eruption victims strongly suggests the rapid vaporization of body fluids and soft tissues of people at death due to exposure to extreme heat.

Radiocarbon analysis of modern olive wood raises doubts concerning a crucial piece of evidence in dating the Santorini eruption.

Charred olive wood is abundant in the archaeological record, especially around the Mediterranean. As the outermost ring closest to the bark is assumed to represent the latest time that the tree was alive, the radiocarbon date obtained from the outermost rings of an olive branch buried during the Santorini volcanic eruption is regarded as crucial evidence for the date of this cataclysmic event. The date of this eruption has far reaching consequences in the archaeology of the Aegean, Egypt and the Levant, and the understanding of their interconnections. We analyzed the radiocarbon concentrations in cross-sections from a modern olive tree trunk as well as from a living branch, and obtained near-annual resolution dates using the radiocarbon "bomb peak". In both cases we show that radiocarbon dates of the last formed wood along the circumference are not chronologically homogenous, and can differ by up to a few decades. Thus the outermost wood layer does not necessarily represent the date of the last year of growth. These findings challenge the interpretation of the results obtained from dating the olive branch from the Santorini volcanic eruption, as it could predate the eruption by a few decades. In addition, our results are also significant for any future studies based on archaeologically preserved olive wood.

A 36,000-Year-Old Volcanic Eruption Depicted in the Chauvet-Pont d'Arc Cave (Ardèche, France)?

Among the paintings and engravings found in the Chauvet-Pont d'Arc cave (Ardèche, France), several peculiar spray-shape signs have been previously described in the Megaloceros Gallery. Here we document the occurrence of strombolian volcanic activity located 35 km northwest of the cave, and visible from the hills above the cave entrance. The volcanic eruptions were dated, using 40Ar/39Ar, between 29 ± 10 ka and 35 ± 8 ka (2σ), which overlaps with the 14C AMS and thermoluminescence ages of the first Aurignacian occupations of the cave in the Megaloceros Gallery. Our work provides the first evidence of an intense volcanic activity between 40 and 30 ka in the Bas-Vivarais region, and it is very likely that Humans living in the Ardèche river area witnessed one or several eruptions. We propose that the spray-shape signs found in the Chauvet-Pont d'Arc cave could be the oldest known depiction of a volcanic eruption, predating by more than 34 ka the description by Pliny the Younger of the Vesuvius eruption (AD 79) and by 28 ka the Çatalhöyük mural discovered in central Turkey.

Timing and climate forcing of volcanic eruptions for the past 2,500 years.

Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.

Methanogenic burst in the end-Permian carbon cycle.

The end-Permian extinction is associated with a mysterious disruption to Earth's carbon cycle. Here we identify causal mechanisms via three observations. First, we show that geochemical signals indicate superexponential growth of the marine inorganic carbon reservoir, coincident with the extinction and consistent with the expansion of a new microbial metabolic pathway. Second, we show that the efficient acetoclastic pathway in Methanosarcina emerged at a time statistically indistinguishable from the extinction. Finally, we show that nickel concentrations in South China sediments increased sharply at the extinction, probably as a consequence of massive Siberian volcanism, enabling a methanogenic expansion by removal of nickel limitation. Collectively, these results are consistent with the instigation of Earth's greatest mass extinction by a specific microbial innovation.

Evaluating marine diets through radiocarbon dating and stable isotope analysis of victims of the AD79 eruption of Vesuvius.

The stable carbon (δ(13) C) and nitrogen (δ(15) N) isotope values of bone collagen are frequently used in paleodietary studies to assess the marine contribution to an individual's diet. Surprisingly, the relationship between stable isotope these values characteristics and the percentage of marine foods in diet has never been effectively demonstrated. To clarify this relationship, the stable isotope values and radiocarbon dates of nine humans and one sheep from Herculaneum, all who perished simultaneously during the AD 79 eruption of Vesuvius, were determined. Significant differences were found in the radiocarbon dates which are attributable to the incorporation of "old" carbon from the marine reservoir. The magnitude of the observed differences was linearly correlated with both δ(13) C and δ(15) N values allowing the response of each isotope to increasing marine carbon in collagen to be independently verified. Regression analyses showed that for every 1‰ enrichment in δ(13) C and δ(15) N, 56 years and 34 years were added to the radiocarbon age, respectively. Predictions of the maximum marine reservoir age differed considerably depending on which stable isotope was considered. This discrepancy is attributed to some degree of macronutrient scrambling whereby nitrogen from marine protein is preferentially incorporated in collagen over marine carbon. It is suggested that the macronutrient scrambling explains the observed relationship between δ(13) C and δ(15) N from Roman coastal sites and should be considered when interpreting any diet which is not dominated by protein. Nevertheless, without knowing the degree of macronutrient scrambling in different dietary scenarios, the accuracy of dietary reconstructions is severely compromised.

Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life.

The Isua Supracrustal Belt, Greenland, of Early Archean age (3.81-3.70 Ga) represents the oldest crustal segment on Earth. Its complex lithology comprises an ophiolite-like unit and volcanic rocks reminiscent of boninites, which tie Isua supracrustals to an island arc environment. We here present zinc (Zn) isotope compositions measured on serpentinites and other rocks from the Isua supracrustal sequence and on serpentinites from modern ophiolites, midocean ridges, and the Mariana forearc. In stark contrast to modern midocean ridge and ophiolite serpentinites, Zn in Isua and Mariana serpentinites is markedly depleted in heavy isotopes with respect to the igneous average. Based on recent results of Zn isotope fractionation between coexisting species in solution, the Isua serpentinites were permeated by carbonate-rich, high-pH hydrothermal solutions at medium temperature (100-300 °C). Zinc isotopes therefore stand out as a pH meter for fossil hydrothermal solutions. The geochemical features of the Isua fluids resemble the interstitial fluids sampled in the mud volcano serpentinites of the Mariana forearc. The reduced character and the high pH inferred for these fluids make Archean serpentine mud volcanoes a particularly favorable setting for the early stabilization of amino acids.

Human corpses as time capsules: new perspectives in the study of past mass disasters.

Looking at the corpses of past natural catastrophes can change completely the conception of how to study human bone remains. The recovery of the Herculaneum victims of the 79 AD Vesuvius eruption was an opportunity for me to adopt a new approach in the study of human skeletons and their context of discovery. During two years of field work, my first aim was to investigate the effects of pyroclastic surges on people and things. The conservation of skeletons and their replacement by fiberglass casts were also provided. This "field laboratory" has developed into a palaeoforensic investigation of the mass disaster caused by the 79 AD natural event. Field and laboratory research, later extended to Pompeii plaster-cast corpses, were also carried out on the victims' remains, footprints, huts and objects found in the sites buried by the prehistoric "Avellino pumices" eruption (3780 ± 100 BP). The new results obtained from the study of the causes of death of people hit by pyroclastic surges produced by past Vesuvius eruptions have proved essential in hazard evaluation in the Neapolitan district and other volcanic areas.

The legacy of Pompeii and its volcano.

On August 24, AD 79, a terrible eruption of Mount Vesuvius deranged life in beautiful Pompeii and killed thousands of men, women, and children. They were restored to us by the fact that Mount Vesuvius, with its rain of ashes, proved to be a skilled sculptor, preserving the shape and even the wrinkles in the clothes the Pompeians wore while trying to escape during the day of the tragedy. The detailed description of Plinius the Younger and modern static studies of the eruptive residues have made it possible to reconstruct with great accuracy the various phases of the eruption that took place 2000 years ago, including the hours and days during which the phenomena first became obvious. Today, almost 2000 years later, Pompeii has reawakened and risen from its sepulcher of ashes thanks to the excavations initiated under King Charles III of Bourbon in 1748. Excavations proceeded slowly under the Bourbons, with the aim of enriching the Bourbon Museum of Naples rather than of classifying the ruins and placing them into a historical context. Under Joachim Murat, interest in the town planning and architecture of the uncovered cities reemerged, especially with respect to Pompeii. In 1860, however, with the establishment of the Kingdom of Italy, the excavations, now under the direction of archaeologist Giuseppe Fiorelli, were provided new impetus and, finally, a scientific basis. Today, the excavations are giving us back extraordinary evidence concerning the culture, the everyday life, the habits, the architecture, and the wonderful frescoes of the Roman cities of southern Italy, making possible the statement that Pompeii is "the most alive of the dead cities."