PETROGRAPHIC AND ISOTOPIC CHARACTERIZATION OF THE MARBLE OF THE ISLAND OF TINOS (GREECE)*

Most outcrops of good‐quality crystalline marble in Mediterranean countries were exploited in Greek and Roman times. Hence, a wide variety of marble is now found in archaeological excavations. The precise determination of the provenance of a marble object is of great archaeological importance, and is now mostly obtained by coupling the petrographic study of a thin section with the analysis of the C and O stable isotopes, or by stereomicroscopy and EPR. The existing databases are considerable but still insufficient, because our knowledge about and study of ancient Mediterranean quarries remain incomplete. The contribution of this research is to add new petrographic and isotopic data on small quarries on the Greek island of Tinos that were exploited in antiquity. This marble belongs to the same geological horizon; it is quite pure, sometimes dolomitic and characterized by a low‐T, high‐P metamorphism that produced a limited recrystallization (MGS varying from 0.64 to 2.50 mm) on marine limestone protoliths. The petrographic features are quite distinctive: the fabric is strongly lineated and often stressed; and the accessory minerals are ubiquitary quartz, ore minerals, graphite and muscovite. As far as the isotopic data are concerned, δ¹³C_PDB varies from 1.1 to 2.7, and δ¹⁸O_PDB from ?1.7 to ?11.4. Both the features and the data have been compared with those of similar marbles used in antiquity, showing that their combination mirrors the fingerprint of the Tinos marble.     

Horticulturists and oxygen ecozones in the tropical and subtropical forests of Southeast South America

We analyse the isotopic values (δ¹³C, δ¹⁵N) of the diet of pre-Columbian horticulturalist populations from tropical and subtropical areas of southeastern South America, belonging to the Guarani and Taquara archaeological units. The data indicate different trends in each one (T?=?4.21; P?=?0.0004), showing a mixed diet with maize consumption in the Guarani samples (δ¹³C_co?=??15.5?±?1.8‰; δ¹³C_ap ?10.4?±?0.8‰) and a depleted one in the Taquara ones (δ¹³C_co ?18.2?±?1.7‰; δ¹³C_ap ?11.9?±?0.9‰), with a significant internal dispersion in both populations. The first population has higher nitrogen values (δ¹⁵N 11.1?±?0.6‰) compared to the Taquara samples (δ¹⁵N 9.3?±?1‰), suggesting a more carnivorous diet. The recognition of these pre-Columbian mixed diets involves the identification of maize cultivation on the Atlantic side of the southernmost area of South America (Parana Delta, 34° SL). Through the analysis of δ¹⁸O we have identified two isotopic ecozones, the first along the Paraná River Valley, with an average value of δ¹⁸O ?3.7?±?0.5‰ (CV?=?13.5%; CI?=??3.83 / ?3.16), and the second one, located in the Planalto of southern Brazil (Araucaria Forest), with a mean value of δ¹⁸O ?1.5?±?0.3‰ (CV?=?16.5%; CI?=??1.69 / ?1.29). The isotopic data (δ¹³C, δ¹⁵N and δ¹⁸O) suggest human movements between these two ecozones.     

Ancient hydrocarbon seeps from the Mesozoic convergent margin of California: carbonate geochemistry, fluids and palaeoenvironments

More than a dozen hydrocarbon seep‐carbonate occurrences in late Jurassic to late Cretaceous forearc and accretionary prism strata, western California, accumulated in turbidite/fault‐hosted or serpentine diapir‐related settings. Three sites, Paskenta, Cold Fork of Cottonwood Creek and Wilbur Springs, were analyzed for their petrographic, geochemical and palaeoecological attributes, and each showed a three‐stage development that recorded the evolution of fluids through reducing–oxidizing–reducing conditions. The first stage constituted diffusive, reduced fluid seepage (CH₄, H₂S) through seafloor sediments, as indicated by Fe‐rich detrital micrite, corroded surfaces encrusted with framboidal pyrite, anhedral yellow calcite and negative cement stable isotopic signatures (δ¹³C as low as ?35.5‰ PDB; δ¹⁸O as low as ?10.8‰ PDB). Mega‐invertebrates, adapted to reduced conditions and/or bacterial chemosymbiosis, colonized the sites during this earliest period of fluid seepage. A second, early stage of centralized venting at the seafloor followed, which was coincident with hydrocarbon migration, as evidenced by nonluminescent fibrous cements with δ¹³C values as low as ?43.7‰ PDB, elevated δ¹⁸O (up to +2.3‰ PDB), petroleum inclusions, marine borings and lack of pyrite. Throughout these early phases of hydrocarbon seepage, microbial sediments were preserved as layered and clotted, nondetrital micrites. A final late‐stage of development marked a return to reducing conditions during burial diagenesis, as implied by pore‐associated Mn‐rich cement phases with bright cathodoluminescent patterns, and negative δ¹⁸O signatures (as low as ?14‰ PDB). These recurring patterns among sites highlight similarities in the hydrogeological evolution of the Mesozoic convergent margin of California, which influenced local geochemical conditions and organism responses. A comparison of stable carbon and oxygen isotopic data for 33 globally distributed seep‐carbonates, ranging in age from Devonian to Recent, delineated three groupings that reflect variable fluid input, different tectono‐sedimentary regimes and time–temperature‐dependent burial diagenesis.     

Thermochemical and bacterial sulfate reduction in the Cambrian and Lower Ordovician carbonates in the Tazhong Area,Tarim Basin,NW China: evidence from fluid inclusions,C, S,and Sr isotopic data

Petrographic features, C, O, S, and Sr isotopes were determined, and fluid inclusions (FI) were analyzed on various stages of vug‐ and fracture‐fillings from the Cambrian and Lower Ordovician reservoirs in the Tazhong area, Tarim basin, NW China. The aim was to assess the origin of pyrite and anhydrite and the processes affecting sulfur during diagenesis of the carbonates. Pyrite from seven wells has δ³⁴S values from ?22‰ to +31‰. The pyrites with low δ³⁴S values from ?21.8‰ to ?12.3‰ were found close to fracture‐filling calcites with vapor‐liquid double‐phase aqueous fluid inclusions homogenization temperatures (FI‐Th) from 55.7 to 73.2°C, salinities from 1.4wt% to 6.59wt% NaCl equiv and δ¹³C values from ?2.3‰ to ?14.2‰, indicating an origin from bacterial sulfate reduction by organic matter. Other sulfides with heavier δ³⁴S values may have formed by thermochemical sulfate reduction (TSR) during two episodes. The earlier TSR in the Middle and Lower Cambrian resulted in pyrites and H₂S having δ³⁴S values from 30 to 33‰, close to those of bedded anhydrite and oilfield water (approximately 34‰). The later TSR is represented by calcites with δ¹³C values as light as ?17.7‰ and FI‐Th of about 120–145°C, and pyrite and H₂S with δ³⁴S values close to those of the Upper Cambrian burial‐diagenetic anhydrite (between +14.8‰ and +22.6‰). The values of the anhydrite are significantly lighter than contemporary seawater sulfates. This together with ⁸⁷Sr/⁸⁶Sr values of anhydrite and TSR calcites from 0.7091 to 0.7125 suggests a source from the underlying Ediacaran seawater sulfate and detrital Sr contribution.     

Changes in fluid pathways in a calcite vein mesh (Natih Formation,Oman Mountains): insights from stable isotopes

We present a structural, microstructural, and stable isotope study of a calcite vein mesh within the Cretaceous Natih Formation in the Oman Mountains to explore changes in fluid pathways during vein formation. Stage 1 veins form a mesh of steeply dipping crack‐seal extension veins confined to a 3.5‐m‐thick stratigraphic interval. Different strike orientations of Stage 1 veins show mutually crosscutting relationships. Stage 2 veins occur in the dilatant parts of a younger normal fault interpreted to penetrate the stratigraphy below. The δ¹⁸O composition of the host rock ranges from 21.8‰ to 23.7‰. The δ¹³C composition ranges from 1.5‰ to 2.3‰. This range is consistent with regionally developed diagenetic alteration at top of the Natih Formation. The δ¹⁸O composition of vein calcite varies from 22.5‰ to 26.2‰, whereas δ¹³C composition ranges from ?0.8‰ to 2.1‰. A first trend observed in Stage 1 veins involves a decrease of δ¹³C to compositions nearly 1.3‰ lower than the host rock, whereas δ¹⁸O remains constant. A second trend observed in Stage 2 calcite has δ¹⁸O values up to 3.3‰ higher than the host rock, whereas the δ¹³C composition is similar. Stable isotope data and microstructures indicate an episodic flow regime for both stages. During Stage 1, formation of a stratabound vein mesh involved bedding‐parallel flow, under near‐lithostatic fluid pressures. The ¹⁸O fluid composition was host rock‐buffered, whereas ¹³C composition was relatively depleted. This may reflect reaction of low ¹³C CO₂ derived by fluid interaction with organic matter in the limestones. Stage 2 vein formation is associated with fault‐controlled fluid flow accessing fluids in equilibrium with limestones about 50 m beneath. We highlight how evolution of effective stress states and the growth of faults influence the hydraulic connectivity in fracture networks and we demonstrate the value of stable isotopes in tracking changes in fluid pathways.     

Fracture-fill calcite as a record of microbial methanogenesis and fluid migration: a case study from the Devonian Antrim Shale, Michigan Basin

The Devonian Antrim Shale is an organic‐rich, naturally fractured black shale in the Michigan Basin that serves as both a source and reservoir for natural gas. A well‐developed network of major, through‐going vertical fractures controls reservoir‐scale permeability in the Antrim Shale. Many fractures are open, but some are partially sealed by calcite cements that retain isotopic evidence of widespread microbial methanogenesis. Fracture filling calcite displays an unusually broad spectrum of δ¹³C values (+34 to ?41‰ PDB), suggesting that both aerobic and anaerobic bacterial processes were active in the reservoir. Calcites with high δ¹³C values (>+15‰) record cementation of fractures from dissolved inorganic carbon (DIC) generated during bacterial methanogenesis. Calcites with low δ¹³C values (13C values between ?10 and ?30‰ can be attributed to variable organic matter oxidation pathways, methane oxidation, and carbonate rock buffering. Identification of ¹³C‐rich calcite provides unambiguous evidence of biogenic methane generation and may be used to identify gas deposits in other sedimentary basins. It is likely that repeated glacial advances and retreats exposed the Antrim Shale at the basin margin, enhanced meteoric recharge into the shallow part of the fractured reservoir, and initiated multiple episodes of bacterial methanogenesis and methanotrophic activity that were recorded in fracture‐fill cements. The δ¹⁸O values in both formation waters and calcite cements increase with depth in the basin (?12 to ?4‰ SMOW, and +21 to +27‰ PDB, respectively). Most fracture‐fill cements from outcrop samples have δ¹³C values between ?41 and ?15‰ PDB. In contrast, most cement in cores have δ¹³C values between +15 and +34‰ PDB. Radiocarbon and ²³⁰Th dating of fracture‐fill calcite indicates that the calcite formed between 33 and 390 ka, well within the Pleistocene Epoch.     

ON THE WHITE AND COLOURED MARBLES OF THE ROMAN TOWN OF CUICUL (DJEMILA,ALGERIA)

This paper reports the results of an archaeometric study of the local and imported marbles found in the Roman town of Cuicul (now Djemila, Algeria), a research project funded by the Sixth Framework Programme of the European Union. Of the few imported coloured lithotypes that have been found, four are of Greek origin and one was imported from Asia Minor. In addition, two other classical Roman coloured stones found on the site are probably of local North African origin (most likely one from Numidia and one from Algeria). With regard to the grey and white marbles employed in the statuary and architecture, petrographic study in thin section and the δ¹³C and δ¹⁸O isotopic data emphasize the frequent use of the local fine‐grained lithotype from Filfila (Skikda) together with imported Greek lithotypes (i.e., Pentelic marble, the dolomitic variety of Thasian marble, and Parian marble from Lakkoi) as well as different varieties of the so‐called ‘greco scritto’, whose provenance in some cases still remains uncertain. In fact, the petrographic and geochemical features of the marbles do not always match those known for the classical ‘greco scritto’ from the quarry of Cap de Garde, near Annaba (Algeria).     

Hydrogeology of the Krafla geothermal system,northeast Iceland

The Krafla geothermal system is located in Iceland's northeastern neovolcanic zone, within the Krafla central volcanic complex. Geothermal fluids are superheated steam closest to the magma heat source, two‐phase at higher depths, and sub‐boiling at the shallowest depths. Hydrogen isotope ratios of geothermal fluids range from ?87‰, equivalent to local meteoric water, to ?94‰. These fluids are enriched in ¹⁸O relative to the global meteoric line by +0.5–3.2‰. Calculated vapor fractions of the fluids are 0.0–0.5 wt% (~0–16% by volume) in the northwestern portion of the geothermal system and increase towards the southeast, up to 5.4 wt% (~57% by volume). Hydrothermal epidote sampled from 900 to 2500 m depth has δD values from ?127 to ?108‰, and δ¹⁸O from ?13.0 to ?9.6‰. Fluids in equilibrium with epidote have isotope compositions similar to those calculated for the vapor phase of two‐phase aquifer fluids. We interpret the large range in δD_EPIDOTE and δ¹⁸O_EPIDOTE across the system and within individual wells (up to 7‰ and 3.3‰, respectively) to result from variable mixing of shallow sub‐boiling groundwater with condensates of vapor rising from a deeper two‐phase reservoir. The data suggest that meteoric waters derived from a single source in the northwest are separated into the shallow sub‐boiling reservoir, and deeper two‐phase reservoir. Interaction between these reservoirs occurs by channelized vertical flow of vapor along fractures, and input of magmatic volatiles further alters fluid chemistry in some wells. Isotopic compositions of hydrothermal epidote reflect local equilibrium with fluids formed by mixtures of shallow water, deep vapor condensates, and magmatic volatiles, whose ionic strength is subsequently derived from dissolution of basalt host rock. This study illustrates the benefits of combining phase segregation effects in two‐phase systems during analysis of wellhead fluid data with stable isotope values of hydrous alteration minerals when evaluating the complex hydrogeology of volcano‐hosted geothermal systems.     

PROVENANCE DETERMINATION OF NEOLITHIC TO CLASSICAL MEDITERRANEAN MARBLES BY STABLE ISOTOPES*

Two stable isotopic data bases for ?¹³C and ?¹⁸O values of marble have been accumulated: (1) 590 analyses from 42 Classical quarries of Greece, western Turkey, Tunisia, and Carrara, Italy, and (2) potential Early Bronze Age (EBA) marble sources in the central Cyclades, comprising 192 analyses from 16 sites on the islands of Paros, Naxos, Ios, and Keros. The data bases include the most important marble occurrences in the eastern Mediterranean and so can be used to source artefacts of any age. Neolithic artefacts found at Franchthi Cave, where no marble occurs locally, have been attributed to the Peloponnese and the Cyclades, direct evidence for early trade. In the Cycladic EBA, Naxos and Keros were the principal marble sources for the abundant artefacts found at Keros. The commercial marble trade in Archaic Greece began in the central Cyclades where the tradition apparently went back some 5000 years, to the Neolithic. Classical Greece and especially Rome expanded the number and locations of commercial marble sources throughout the Mediterranean.     

Metamorphic and basin fluids in quartz–carbonate–sulphide veins in the SW Scottish Highlands: a stable isotope and fluid inclusion study

Metalliferous (Fe–Cu–Pb–Zn) quartz–carbonate–sulphide veins cut greenschist to epidote–amphibolite facies metamorphic rocks of the Dalradian, SW Scottish Highlands, with NE–SW to NW–SE trends, approximately parallel or perpendicular to regional structures. Early quartz was followed by pyrite, chalcopyrite, sphalerite, galena, barite, late dolomite–ankerite and clays. Both quartz–sulphide and carbonate vein mineralisation is associated with brecciation, indicating rapid release of fluid overpressure and hydraulic fracturing. Two distinct mineralising fluids were identified from fluid inclusion and stable isotope studies. High temperature (>350°C) quartz‐precipitating fluids were moderately saline (4.0–12.7 wt.% NaCl equivalent) with low (approximately 0.05). Quartz δ¹⁸O (+11.7 to +16.5‰) and sulphide δ³⁴S (?13.6 to ?1.1‰) indicate isotopic equilibrium with host metasediments (rock buffering) and a local metasedimentary source of sulphur. Later, low‐temperature (T_H = 120–200°C) fluids, probably associated with secondary carbonate, barite and clay formation, were also moderately saline (3.8–9.1 wt.% NaCl equivalent), but were strongly enriched in ¹⁸O relative to host Dalradian lithologies, as indicated by secondary dolomite–ankerite (δ¹⁸O = +17.0 to +29.0‰, δ¹³C = ?1.0 to ?3.0‰). Compositions of carbonate–forming fluids were externally buffered. The veins record the fluid–rock interaction history of metamorphic host rocks during cooling, uplift and later extension. Early vein quartz precipitated under retrograde greenschist facies conditions from fluids probably derived by syn‐metamorphic dehydration of deeper, higher‐grade rocks during uplift and cooling of the Caledonian metamorphic complex. Veins are similar to those of mesothermal veins in younger Phanerozoic metamorphic belts, but are rare in the Scottish Dalradian. Early quartz veins were reactivated by deep penetration of low‐temperature basin fluids that precipitated carbonate and clays in veins and adjacent Dalradian metasediments throughout the SW Highlands, probably in the Permo‐Carboniferous. This event is consistent with paragenetically ambiguous barite with δ³⁴S characteristic of late Palaeozoic basinal brines.     

PALAEOCLIMATIC IDENTIFICATION BASED ON AN ISOTOPE STUDY OF TRAVERTINE FROM THE COPPER AGE SITE AT LOS MILLARES,SOUTH-EASTERN SPAIN*

Remains of an aqueduct from the Copper Age settlement of Los Millares have been studied. The isotope results (—7‰ < δ¹⁸O — 5.3‰) show that the aqueduct was used to transport fresh water at room temperature. The results are inconsistent with the aqueduct being used for hot water transport or as a container for water exposed to evaporation processes. Both isotopic and mineralogical results were useful in identifying the origin and use of building materials and also in determining climatic conditions during the time of the settlement occupation.     

THE PROVENANCE AND TECHNOLOGY OF NEAR EASTERN GLASS: OXYGEN ISOTOPES BY LASER FLUORINATION AS A COMPLEMENT TO STRONTIUM*

The ability to make rapid measurements on small samples using laser fluorination enhances the potential of oxygen isotopes in the investigation of early inorganic materials and technologies. δ¹⁸O and ⁸⁷Sr/⁸⁶Sr values are presented for glass from two primary production sites, four secondary production sites and a consumer site in the Near East, dating from Late Antiquity to the medieval period. δ¹⁸O is in general slightly less effective than ⁸⁷Sr/⁸⁶Sr in discriminating between sources, as the spread of measured values from a single source is somewhat broader relative to the available range. However, while ⁸⁷Sr/⁸⁶Sr is derived predominantly from either the lime‐bearing fraction of the glass‐making sand or the plant ash used as a source of alkali, δ¹⁸O derives mainly from the silica. Thus the two measurements can provide complementary information. A comparison of δ¹⁸O for late Roman – Islamic glasses made on the coast of Syria–Palestine with those of previously analysed glasses from Roman Europe suggests that the European glasses are relatively enriched in ¹⁸O. This appears to contradict the view that most Roman glass was made using Levantine sand and possible interpretations are discussed.     

Isotopic Reconstruction of the Late Longshan Period (ca. 4200–3900 BP) Dietary Complexity before the Onset of State‐Level Societies at the Wadian Site in the Ying River Valley,Central Plains,China

During the late Longshan period (ca. 4200–3900 BP) settlements on the Central Plains of China underwent a diversification in food production technologies, which set the stage for rapid economic and social development. The introduction of novel domesticates such as rice, wheat, cattle, and sheep not only provided more food choices, but also changed ideas concerning land use, farming techniques, and the use and mobilization of large scale labor forces. To better understand the contribution that these new dietary items and practices made to shaping the late Longshan period societies, a stable isotope ratio study of humans (n = 12) and animals (n = 42) was conducted at the late Longshan period site of Wadian. The human δ¹³C and δ¹⁵N values are clustered into two distinct groups. One group of nine individuals (δ¹³C = −9.9 ± 0.7‰; δ¹⁵N = 7.5 ± 0.5‰) had a predominately C₄ diet based on millet grains with little protein input from the domestic animals. The other group of three individuals (δ¹³C = −14.3 ± 0.8‰; δ¹⁵N = 10.2 ± 0.3‰) had a mixed C₃/C₄ diet of millets and rice and were consuming sheep and cattle. The animals also displayed dietary diversity with the pigs (δ¹³C = −11.3 ± 2.5‰; δ¹⁵N = 6.9 ± 1.0‰, n = 10) and dogs (δ¹³C = −10.1 ± 1.0‰; δ¹⁵N = 7.2 ± 1.1‰, n = 7) having mostly a C₄ plant based diet (millets). In contrast, the cattle (δ¹³C = −12.8 ± 2.1‰; δ¹⁵N = 7.6 ± 0.7‰, n = 9), sheep (δ¹³C = −16.7 ± 0.9‰; δ¹⁵N = 7.6 ± 0.1‰, n = 2), and cervids (δ¹³C = −20.8 ± 0.9‰; δ¹⁵N = 5.0 ± 1.2‰, n = 10) had diets with a greater contribution from C₃ sources such as rice and wild plants. The discovery that humans and animals had different subsistence patterns indicates dietary complexity at Wadian and that rice agriculture, and cattle and sheep husbandry practices were already an important part of the local economy by the late Longshan period in the southern region of the Central Plains of China. Copyright © 2015 John Wiley & Sons, Ltd.     

The sources and formation processes of brines from the Lunnan Ordovician paleokarst reservoir,Tarim Basin,northwest China

The most important petroleum exploration target in the Tarim Basin, northwest China, is the paleokarst reservoir. To understand the source and evolution of brine in this type of reservoir, a total of 37 formation‐water samples were collected from the Middle‐Lower Ordovician paleokarst reservoir in the Lunnan oilfield. The δD‐δ¹⁸O correlation and Cl/Br ratios reflect the mixture of two fluids: meteoric water and evaporated seawater. The different degree of mixture divided samples into two groups. Group 1 samples, from deep strata (5150–6667 m.b.s.l.) in the east of the field, with elevated δD (?53.5 to ?38.0‰), δ¹⁸O values (0.66–5.99‰), and lower Cl/Br ratios (336–478 for Cl/Br, except LN634‐1 and LN631‐1) were formed by evaporation of seawater plus a small contribution from meteoric water. Group 2 samples, from shallow strata (5038–6067 m.b.s.l.), in the west of the field, have contrasting features (?59.6 to ?48.5‰ for δD, ?0.47 to 2.17‰ for δ¹⁸O, and 501 to 871 for Cl/Br), which reflect a mixture of evaporated seawater with a high proportion of meteoric water. Both of the fluid types exchanged oxygen isotope with minerals. The investigation into cation composition reveals that, before entering into the current reservoir, waters suffered albitization of plagioclase; moreover, meteoric water dissolved evaporites and seawater experienced dolomitization. A mixing trend showed by strontium isotopes (0.709801–0.711628) gave further evidence for the mixture of two fluid types. Based on the correlation of geological history with our data, two infiltration models of meteoric waters can be constructed. According to the chemical and isotopic compositions of the waters, an east fluid regime (Group 1) and a west fluid regime (Group 2) have thus been defined. Better understanding of the subsurface fluid movement patterns may be helpful for the local exploration.     

CARBON AND OXYGEN ISOTOPIC RATIOS: A DATA BASE FOR CLASSICAL GREEK AND ROMAN MARBLE

An isotopic data base of δ¹³C and δ¹⁸O analyses of 528 samples collected from 39 classical Greek and Roman quarries of Turkey, Greece, Italy and Tunisia has been accumulated. The discriminative possibilities of the data base vary from quarry to quarry. Most quarries have a distinctive pattern for either or both variables, but some have more than one grouping. The data also overlap for many quarries preventing a unique provenance assignment. If the alternatives are known so that the total pool of possible sources is reduced, the data base can then discriminate and assign a provenance for most classical marble artifacts.     

Oxygen isotopes in cellulose identify source water for archaeological maize in the American Southwest

Maize (Zea mays) was a primary food crop for aboriginal societies of the arid American Southwest. Water used for maize production in these arid zones could have come from precipitation and runoff during the summer monsoon, from perennial streams and springs, or from stored soil water fed by snowmelt. The oxygen stable isotope ratio (δ¹⁸O) of summer and winter precipitation on the Colorado Plateau naturally differ by more than 10‰ providing a powerful tool for distinguishing winter- from summer-derived water sources used in cultivation of maize. We investigated whether variation in δ¹⁸O of potential source waters is preserved in the δ¹⁸O of cellulose (δ¹⁸O_cellulose) of maize cobs by growing four aboriginal and one modern maize variety in pots irrigated with water of known δ¹⁸O composition. The δ¹⁸O_cellulose values of cobs ranged from 26.8 to 36.4‰ (averaged within varieties) and were highly correlated with δ¹⁸O values of the source irrigation water (−15.8 to −8.2‰). Cob δ¹⁸O_cellulose from five archaeological sites on the Colorado Plateau in southeastern Utah ranged from 27.3 to 34.6‰, closely matching the range of values observed in experimental plants. A δ¹⁸O_cellulose model developed originally for tree rings was parameterized and applied to the archaeological maize cobs. The model indicated that monsoonal precipitation accounted for 0–20% of the moisture for archaeological cob samples from a site adjacent to a perennial stream and 43–98% for samples from an upland site, more distant from a perennial water source. These results reveal the potential for using δ¹⁸O_cellulose to investigate prehistoric irrigation practices and source water used for maize production in the American Southwest.     

Multi-Isotope Investigations for Scientific Characterisation and Provenance Implication of Banded Travertines from Tripolis Antique City (Denizli–Turkey)

The coloured stones used in buildings and monuments were an indicator of power and wealth during the ancient times. In this study, Tripolis city samples have been compared with Tripolis quarry samples in order to recognise the provenance of the banded travertine blocks in the ancient city. The banded travertine samples have similar mineral compositions and mainly consist of calcite with minor amounts of dolomite, aragonite, clay and iron oxide minerals. These results are also supported by CRS studies. Calcite is in the form of needle-shaped crystals ranging between 0.163–1.418?mm (in city) and 0.303–1.270?mm (in quarry). Tripolis banded travertine samples show the similar compositional spread in terms of major oxide, trace elements. δ¹³C_V-PDB values of banded travertines range from 1.93 to 5.25‰ (in city) and 2.99 to 3.99‰ (in quarry), δ¹⁸O_V-PDB values change between (?16.93)–(?10.08) ‰ and (?15.93)–(?13.01)‰, respectively. The U–Th radiometric ages are determined between ～267 and 9?ka in Tripolis city samples and ～350 and 2?ka in Tripolis quarry samples. The minero-petrographic, geochemical, C–O and U–Th isotope results fairly matched with each other. It seems highly probable that the banded travertines in Tripolis city were extracted from the Tripolis quarry, which is located at the northeast of the antique city with a distance of 3?km.     

A comprehensive review of hydrocarbons and genetic model of the sandstone‐hosted Dongsheng uranium deposit,Ordos Basin,China

The Dongsheng uranium deposit, the largest in situ leach uranium mine in the Ordos Basin, geometrically forms a roll‐front type deposit that is hosted in the Middle Jurassic Zhiluo Formation. The genesis of the mineralization, however, has long been a topic of great debate. Regional faults, epigenetic alterations in surface outcrops, natural oil seeps, and experimental findings support a reducing microenvironment during ore genesis. The bulk of the mineralization is coffinite. Based on thin‐section petrography, some of the coffinite is intimately intergrown with authigenic pyrite (ore‐stage pyrite) and is commonly juxtaposed with some late diagenetic sparry calcite (ore‐stage calcite) in primary pores, suggesting simultaneous precipitation. Measured homogenization temperatures of greater than 100°C from fluid inclusions indicate circulation of low‐temperature hydrothermal fluids in the ore zone. The carbon isotopic compositions of late calcite cement (δ¹³C_VPDB = ?31.0 to ?1.4‰) suggest that they were partly derived from sedimentary organic carbon, possibly from deep‐seated petroleum fluids emanating from nearby faults. Hydrogen and oxygen isotope data from kaolinite cement (δD = ?133 to ?116‰ and δ¹⁸O_SMOW = 12.6–13.8‰) indicate that the mineralizing fluids differed from magmatic and metamorphic fluids and were more depleted in D (²H) than modern regional meteoric waters. Such a strongly negative hydrogen isotopic signature suggests that there has been selective modification of δD by CH₄±H₂S±H₂ fluids. Ore‐stage pyrite lies within a very wide range of δ³⁴S (?39.2 to 26.9‰), suggesting that the pyrite has a complex origin and that bacterially mediated sulfate reduction cannot be precluded. Hydrocarbon migration and its role in uranium reduction and precipitation have here been unequivocally defined. Thus, a unifying model for uranium mineralization can be established: Early coupled bacterial uranium mineralization and hydrocarbon oxidation were followed by later recrystallization of ore phases in association with low‐temperature hydrothermal solutions under hydrocarbon‐induced reducing conditions.     

CATHODOLUMINESCENCE OF WHITE MARBLES: AN OVERVIEW*

Identifying the source area of white marbles has long been a problem in archaeology. To address this problem, about 1000 samples from known Classical quarrying areas in Greece, Italy and Turkey were analysed using cathodoluminescence. Twenty-one cathodomicrofacies were recognized, each of which generally characterizes a given area. In cases where the cathodomicrofacies is common to more than one area, δ¹³C and δ¹⁸O signatures provide an effective complementary dataset which allows additional distinctions. Determination keys for the 21 cathodomicrofacies observed are proposed based upon their principal cathodoluminescence colour, and their stable isotopic signature.     

BIOARCHAEOLOGICAL ANALYSIS OF SUBSISTENCE AND HEALTH AT THE LAKE GEORGE SITE,MISSISSIPPI (22YZ557)

Abstract

Bioarchaeological investigations of subsistence and health were conducted on a skeletal population from the Lake George site (22YZ557), a large prehistoric settlement in the lower Yazoo basin of west-central Mississippi. Subsistence is inferred from oral health indicators (including dental caries, calculus, periodontal disease, abscesses, antemortem tooth loss, and macrowear) and stable carbon and nitrogen isotope ratios from bone collagen and apatite. Health is inferred from nonspecific indicators (including cranial porous lesions, enamel hypoplasias, and Harris lines). The sample includes 25 adults and 25 subadults, all of which date to the Coles Creek period (A.D. 700–1200). Frequencies of all pathological conditions are reported for the entire sample and divided by sex and age for adults. Results indicate a heavy pathology load at Lake George, but one that is not dissimilar to other Coles Creek populations. Isotope values indicate a diet that included primarily C3 plants (δ¹³C_Col = ?21.03‰, δ¹³C_Ap-Diet = ?22.06) and terrestrial protein (δ¹⁵N = 9.72‰). The sources of nonspecific pathologies are attributed to stressors associated with increasing population density and cultural complexity that occurred during the Coles Creek period.