Radiogenic Isotope Geochemistry

Altica is a rare first-farming village site in the Basin of Mexico that has survived to modern times. Thus, it provides a glimpse into life during the Early–Middle Formative period. While valuable archaeological information on the village was recovered in excavation, only four burials comprising four individuals were recovered, a very small sample. Two individuals are older-aged females; the third, a middleaged male, was accompanied by prestigious nonperishable goods and indicates that there are status differences even at this early date. The final individual was a young male buried in a deviant manner, suggesting possible foul play. While all individuals have indicators of
periods of poor health, stable isotopes of carbon and nitrogen paint a more complete picture of the types of foods these individuals consumed over their lifetime. Radiogenic strontium isotopes of tooth enamel identify one individual, the young male buried in a deviant manner, as non-native to the Altica region. Thus, there is mystery in the manner of death, but even in this small sample, the wider connections Altica had that are so evident in the artefactual analysis are found in the skeletons. In addition, accelerator mass spectrometry radiocarbon dating provides a chronology of occupation through the people.

Torud-Ahmad Abad magmatic belt is located 175 km east and southeast of Shahrood in the northern part of the Central Iran Structural Zone and includes a thick sequence of Paleocene to middle Eocene volcanic and volca-nosedimentary rocks. This magmatic belt was formed by numerous hypabyssal igneous adakitic domes constituting basaltic andesite, andesite, trachyandesite, dacite, trachydacite, and dacite. The investigated rocks are mainly composed of pyroxene, amphibole, and plagioclase, with minor biotite and opaque minerals. Mineral chemical analysis reveals that plagioclase composition varies from albite to labradorite, clinopyroxene varies from diopside to augite, and amphibole varies from Mg-hastingsite to Mg-hornblende. Amphibole geothermobarometry suggests crystallization temperatures of 850-1050 °C, at 2-6 kbar and the temperature of 920-970 °C, at a pressure of 3-4.5 kbar, which are conditions in agreement with andesite and dacite formation. Clinopyroxene crystallized at temperatures of 1020-1170 °C, at 2-10 kbar, indicating crys-tallization at crustal depths of maximum 30 km for the studied intrusive rocks in the Torud-Ahmad Abad magmatic belt.

Excavations from the La Ventilla 1992-1994 project resulted in the recovery of over 400 individuals across four apartment compounds or frentes, the common household structure at Teotihuacan. Of these compounds, Frente 2 (El Conjunto de los Glifos) has been identified as a higher-status residential community while Frente 3 (El Conjunto de los Artesanos) consisted of lower-status, working-class individuals. Strontium (87Sr/86Sr) isotope ratios from human tooth enamel are examined from over 100 individuals to identify long- and short-distance mobility patterns across Frentes 2 and 3, and to directly test the hypothesis that lower socioeconomic classes of people were more mobile than those of higher status. This poster presents the preliminary isotopic data with more results to follow.

This paper ai on both water balance of the lake and water isotopic composition of H-2 and O-18. According to lake water balance, a water loss of 3,738,905 m³ for the hydrologic year 014, was evaluated. These consistent data favour the opinion that a continuous groundwater outflow from the lake is present and it is conditioned by the intensively
developed fracture system in the lake basement formations. This was also supported by the isotopic analysis (H-2 and O-18) of the sampled waters. Most of water samples taken from hydrologic components of Lake Badovc fall on a linear plot of δ2H versus δ18O showing an isotopic variation typical for waters evaporated from a lake and fits
very well with Global Meteoric Water Line (GMWL), while two rain water samples are isotopically lighter (more negative δ values). Water samples taken from water leakages on the right side of the dam, the piezometer, two wells drilled in the valley downstream of dam, Hajvalia mine gallery and the water flow downstream of the dam, have isotopic composition similar with that of the lake water. Water of Hajvalia mine well shows isotopic composition that falls between that of rain water and lake water.
Considering δ values of rain water (δ2H= -129.6‰, δ18O= -16.56‰) and lake water (δ2H= -67.2‰, δ18O= -9.20‰) and mine water (mixture) (δ2H= -73.3‰, δ18O= 10.15‰) was found that the fraction of rain water in mine water ranges from 6% (according H-2) to 10% (according O-18), while the fraction of lake water in mine water varies from 94% (according H-2) to 90% (according O-18).

Given that oceanic basalts form by partial melting of mantle peridotites that rise below mid-ocean ridges, peridotite and basalt should have identical Sr and Nd isotope ratios. We tested this concept on parallel sets of peridotites and basalts sampled from an exposed section of lithosphere representing 20 m.y. of accretion at the Mid-Atlantic Ridge. The 143Nd/144Nd ratios of the basaltic

Strontium isotopes, water chemistry and whole rock chemistry have been used to investigate the evolution of water from its surface meteoric composition into methane-rich groundwater. Previous studies established that co-produced Surat Basin coal seam gas waters from the Walloon Subgroup (Queensland, Australia) are meteoric in origin and are distinct across the main production regions but the dominant hydrochemical processes have yet to be determined. In this study, strontium isotope ratios (87Sr/86Sr) were measured on production waters from 36 coal seam gas wells, 14 sequentially leached host rock samples and 6 whole rock samples to improve understanding of the water-rock reactions that control spatial variability in solute and isotope chemistry.

Strontium isotope ratios of Walloon Subgroup production waters across all production areas are uniformly low in value, ranging from 0.70338 to 0.70456. The majority of values are significantly lower than shallow Walloon formation waters in the recharge zone and extend the lower range of 87Sr/86Sr ratios recorded for Surat Basin groundwaters. These very low 87Sr/86Sr ratios (0.70338) are reached early along the flow paths, within 10 km of the shallow recharge area waters, before then undergoing a gradual increase with flow distance. Mineralogical and geochemical analyses of whole rock samples representing each of the main lithologies across the Walloon Subgroup has identified that the low 87Sr/86Sr ratios are not derived from any one interval but rather the combination of the same few minerals that are present in every unit.

The rapid accumulation of relatively non-radiogenic strontium early in the flow path across all three gas producing regions has been attributed to a combination of fluid-rock interactions occurring within the Walloon Subgroup itself. Initial surface 87Sr/86Sr ratio values are quickly dominated through a combination of processes whereby recharge waters with low Sr concentrations are absorbed onto montmorillonite clays via cation exchange and this combined with weathering of plagioclase causes a re-equilibration of the groundwater to lower 87Sr/86Sr ratios. Strontium ratios then start to slowly increase again with flow distance through silicate weathering of K-feldspars and muscovites, which are present at low levels across the basin. Local geological features such as the Hutton-Wallumbilla fault and the Kogan and Undulla anticlines appear to influence flow paths and consequently water and gas composition.

Production rates of cosmogenic nuclei are modulated by the variation of the magnetic strength of the Sun, while the atmospheric concentrations of theses isotopes are further controlled by many other factors. The atmospheric concentration of several isotopes and the change of solar activity and hence secondary neutron flux has already been proven. The temporal atmospheric variation of the most studied cosmogenic isotopes (14 C, 7 Be and 10 Be) shows a significant correlation with solar cycles. However, since the artificial tritium (radioactive hydrogen isotope, 3 H) input to the atmosphere due to nuclear weapon tests suppressed the expected variations of tritium production rate by three orders of magnitude, the natural variation of tritium in meteoric precipitation could not be detected so far. We have been analysing the tritium concentration of precipitation for more than 13 years. These results suggest a connection between the solar cycle and the tritium content of precipitation. Previous model calculations have shown that the tritium production rate has a periodic variability of 5% during a solar cycle. Due to the dilution effect of the atmospheric moisture, this effect is supposed to be further weakened in the surface precipitation. In the Danube-Carpathian region the natural tritium level in the precipitation is around 5−10 TU. These low concentrations can be accurately measured only since the last 2−3 decades. Moreover, since the 50's the atmospheric thermonuclear bomb tests increased the tritium amount of precipitation by 2-3 orders of magnitude. After its maximum intensity in the early 60's, the so-called bomb peak has already diminished to a stable level, and in the 2000's years it is close to a natural level (~10 TU). In the period of 2001−2014, we have been connuously taking water samples from each precipitation events. Our study shows how the tritium concentration of monthly precipitations depends on the magnetic activity of the Sun. It can be observed that tritium concentration is varying by about 30% around mean value during the 11 years of the solar cycle. This is in accordance with the time series of other cosmogenic isotopes like 7 Be, 10 Be in the precipitation. We found trends in tritium time series for numerous locations worldwide being similar to the variation of secondary neutron flux and sun spot numbers. These variables seem to have similar

Given that oceanic basalts form by partial melting of mantle peridotites that rise below mid-ocean ridges, peridotite and basalt should have identical Sr and Nd isotope ratios. We tested this concept on parallel sets of peridotites and basalts sampled from an exposed section of lithosphere representing 20 m.y. of accretion at the Mid-Atlantic Ridge. The 143 Nd/ 144 Nd ratios of the basaltic glasses stay constant, whereas those of the peridotitic clinopyroxenes extend both higher and lower than the basalt ratios, suggesting that the constant isotopic composition of the basalts results from mixing of melts released by pe-ridotites from a broad region of the subridge mantle. The degree of melting undergone by the peridotites correlates inversely with their 143 Nd/ 144 Nd ratios. Small-scale isotopic heterogeneity of the peridotites may result from variable premelting metasomatism in the mantle, mostly during periodic, dynamic, subridge upwelling, possibly superimposed upon time-integrated radioactive decay of ancient heterogeneities.

In tectonically active areas, CO2-rich fluids precipitate travertine deposits along the fault zones. These deposits may also be accompanied by vein-type carbonate injections (dyke or sill) and breccia sediments. In this study, we discuss the preliminary results of geochronological (U-Th), isotopic (13C–18O and 87Sr/86Sr) and geochemical (REE+Y) analyses on samples collected from the Akkaya fissure-ridge and vein-type travertines in the Eskipazar-Karabük region. The Akkaya travertines are located 5 km north of North Anatolian Fault Zone (NAFZ) which is seismically active. Approximately 1 km north of the İmanlar village (Eskipazar), the fissure-ridge travertines and, in a close proximity, detritus-poor bedded travertines cut by a several thin calcite veins are observed. This fissure-ridge travertine with fracture space of about 3 cm and length of 90 m extends nearly in N-S direction and is precipitated from thermal waters leaking from pools at the northern edge where gases are also expelled. At just west, stratigraphically below the fissure-ridge travertine, the İmanlar bedded travertines traversed by a network of calcite veins and associated breccia deposits were found.

U-Th ages of fissure-ridge and vein travertines are 21.1 to 92.9 ka and 0.86 to 29.9 ka, respectively. There are also young injections (e.g. 1.8 ka) cutting the vein-type travertines. 13C and 18O values of travertines are +4.66 to +8.68 (‰ VPDB) and –15.86 to –7.67 (‰ VPDB). 87Sr/86Sr values are quite uniform ranging from 0.707336 to 0.707410. PAAS-normalized rare earth element + yttrium (REE+Y) compositions are quite low. REE patterns of underlying vein-type travertines are about 10 to 50-fold higher than those of fissure-ridge travertine.

Keywords: Akkaya (Eskipazar) travertines, calcite veins, stable (C-O) isotope, radiogenic (U-Th-Sr) isotope, rare earth elements

This study was supported by the TUBITAK project 114Y544.

ÖZ Tektonik olarak aktif olan bölgelerde CO 2 'çe zengin akışkanlar fay zonları boyunca yüze-ye ulaşarak traverten çökeltirler. Ayrıca bu çökeller içerisinde damar şeklinde (dayk veya sil benzeri) gelişen karbonat enjeksiyonları ve bunlara eşlik eden breş çökellerine de rastlanır. Bu çalışmada Eskipazar-Karabük bölgesindeki Akkaya sırt tipi ve damar travertenlerinden toplanan örnekler üzerinde gerçekleştirilmiş jeokronolojik (U-Th), izotopik (δ 13 C–δ 18 O ve 87 Sr/ 86 Sr) ve jeokimyasal (NTE+Y) analizlerin ön sonuçları tartışılmıştır. Akkaya travertenleri, sismik olarak oldukça aktif olan Kuzey Anadolu Fay Zonunun yaklaşık 5 km kuzeyinde yer alır. Eskipazar-İmanlar köyünün 1 km kuzeyinde sırt tipi traverten ve bunun hemen batısın-da kalsit damarları içeren detritik materyal barındırmayan tabakalı travertenler oluşmuştur. Çatlak açıklığı 3 cm, sırt ekseni K–G doğrultusunda ve uzunluğu 90 m olan söz konusu sırt tipi traverten kuzey ucunda içinden gaz çıkışlarının olduğu havuzlardan sızan sıcak sulardan güncel olarak çökelmektedir. Bunun hemen batısında, stratigrafik olarak sırt tipi travertenin altında, İmanlar tabakalı travertenleri ve bunları kesen damar travertenler ve bunlarla ilişkili breş çökelleri bulunmaktadır. Damar ve sırt tipi travertenlerin U-Th yaşları sırasıyla 21.1ile 92.9 bin yıl ve 0.86 ile 29.9 bin yılarasında değişmektedir. Damar tipi travertenleri kesen ve yaşları 1.8 bin yıla kadar inen genç enjeksiyonlarda tespit edilmiştir. Travertenlerin d 13 C değerleri +4.66 ile +8.68 (‰ VPDB) ve d 18 O değerleri de –15.86 ile –7.67 (‰ VPDB) arasındadır. 87 Sr/ 86 Sr oranları ise oldukça tekdü-ze olup 0.707336'dan 0.707410'a kadar değişmektedir. PAAS'e göre karşılaştırılmış nadir toprak element + itriyum (NTE+Y) bileşimleri oldukça düşüktür. Ancak tabanda yer alan da-mar tipi travertenler üzerlerindeki sırt tipi travertenlere göre yaklaşık 10-50 kat daha zengin bir element deseni sunarlar. Bu çalışma TÜBİTAK 114Y544 kod nolu proje tarafından desteklenmektedir. Anahtar Kelimeler: Akkaya (Eskipazar) travertenleri, kalsit damarları, duraylı (CO) izotop, radyojenik (U-Th-Sr) izotop, nadir toprak elementleri

The geochemical characteristics (major & trace elements including REE) are studied on the granitic rocks from NW of Ladakh batholith region that emplaced in the western part of Leh area around the Trans-Himalaya of Ladakh district, Jammu & Kashmir (NW India). The major element geochemistry reveals that these granitic rocks display a broad spectrum of SiO content (54.50 wt%-75.80 wt%). The oxide of K O, Al O , MgO & Fe O shows negative correlation with SiO probably shows the fractionation of biotite during the process of crystallization. The oxide of CaO & TiO2 shows positive correlation that coupled with their negative correlation with SiO most probably reflects the fractionation of Sphene (CaTiSiO). The fractionation of apatite is also indicated by the positive correlation with CaO & P O and their negative correlation with SiO. The classified diagram between Molar Al O / (CaO+Na O+K O) vs Molar Al O / (Na O+K O) shows that all samples covered peraluminous region. The total alkali diagram of (Na O+K O) wt% vs SiO (wt %) shows that all samples covered the region of granite, quartz diorite & diorite. The samples plot between K O (wt %) vs SiO (wt %) shows high to medium –K (calc-alkaline) series. All these intrusive rock shows enrichment in LILE (K, Rb, Ba, & Th) and LREE (Ce) relative to the HFSE (Ta, Nb, Hf, Zr, Sm, Y, & Yb). The Chondrite-normalized REE patterns for the studied granitic rocks such as LREE & MREE and HREE's are moderately fractionated & have moderate negative Eu anomalies. In the Nb Vs Y and Rb-(Y+Nb) diagrams, all intrusive rocks fall into the VAG (volcanic-arc granite) field in order to characterize tectonic environment for the granitic rocks. The Al O /TiO vs CaO/Na O diagram & Rb/Ba vs Rb/Sr plots are used for identifying the source of melts parental to peraluminous granites. The variations that observed in granitoid are not only by partial melting but also depend on various processes like migration of melts, magma mixing, assimilation & fractional crystallization. Geochemical studies indicate strong peraluminous behavior with high content of SiO , K O/ Na O ratio that suggest the characteristics of S-type granite. Most of the granitoid samples indicate their volcanic-arc nature but some of them shows syn-collisional tectonic setting as well. 2 2 2 3 2 3 2 2 5 2 5 2 2 3 2 2 2 3 2 2 2 2 2 2 2 2 3 2 2 2 2 2 Plain Language Summary The major element geochemistry of these granitic rocks shows SiO content (54.50 wt%-75.80 wt%). The oxide of K O, Al O , MgO & Fe O shows negative correlation with SiO probably shows fractionation of biotite during the process of crystallization. The oxide of CaO & TiO2 shows positive correlation that coupled with their negative correlation with SiO most probably reflects the fractionation of Sphene (CaTiSiO). The classified diagram between Molar Al O / (CaO+Na O+K O) vs Molar Al O / (Na O+K O) shows that samples covered peraluminous region. The total alkali diagram of (Na O+K O) wt% vs SiO (wt %) shows that all samples covered the region of granite, quartz diorite & diorite. All these intrusive rock shows enrichment in LILE (K, Rb, Ba, & Th) and LREE (Ce) relative to the HFSE (Ta, Nb, Hf, Zr, Sm, Y, & Yb). The Chondrite-normalized REE patterns for the studied granitic rocks such as LREE & MREE and HREE's are moderately fractionated & have moderate negative Eu anomalies. In the Nb Vs Y and Rb-(Y+Nb) diagrams, all intrusive rocks fall into the VAG (volcanic-arc granite) field. Geochemical studies indicate strong peraluminous behavior with high content of SiO , K O/ Na O ratio that suggest the characteristics of S-type granite. 2 2 2 3 2 3 2 2 5 2 3 2 2 2 3 2 2 2 2 2 2 2 2

A B S T R A C T Large amounts of mineral dust are exported from North Africa across the Atlantic Ocean, impacting the atmosphere and ocean during transport and after deposition through biogeochemical processes. In order to characterize the isotopic signature of dust from different seasons and years, in relation to their bulk particle size, and to obtain a general idea of its provenance, Saharan dust was collected using subsurface sediment traps moored in the tropical North Atlantic Ocean in 2012–2013, and by shipboard aerosol collection during three transAtlantic research cruises in 2005, 2012 and 2015. The samples were analysed for radiogenic Strontium (Sr), Neodymium (Nd), and Hafnium (Hf) isotopes, rare earth element (REE; La-Lu) abundances and particle size. In addition, soil sediments from Mauritania, a potential source area, were analysed and compared to the Atlantic dust samples. The results indicate no relation between Sr and Nd isotopic compositions and dust particle size. In contrast, Hf isotopic compositions show a strong relation with particle size, associated to the so-called zircon effect. We explored alternative sources of lithogenic particles to the sediment traps such as Amazon River sediments. Our results reveal that the sediment-trap samples bear distinctly different geochemical signatures from sediments from the Amazon Basin and Amazon River tributaries, and confirm that the primary source of lithogenic particles is northern Africa. The collected dust samples show close relations to African dust aerosols collected at Barbados and samples from the Bodélé Depression, although differences between seasons are observed, which we relate to differences in source areas.