Oxygen isotope analysis of bone and tooth enamel phosphate from paleogene sediments: Experimental techniques and initial results (original) (raw)
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The antiquity and decline of the Bronze Age Harappan civilization in the Indus-Ghaggar-Hakra river valleys is an enigma in archaeology. Weakening of the monsoon after ~5 ka BP (and droughts throughout the Asia) is a strong contender for the Harappan collapse, although controversy exists about the synchroneity of climate change and collapse of civilization. One reason for this controversy is lack of a continuous record of cultural levels and palaeomonsoon change in close proximity. We report a high resolution oxygen isotope (δ 18 O) record of animal teeth-bone phosphates from an archaeological trench itself at Bhirrana, NW India, preserving all cultural levels of this civilization. Bhirrana was part of a high concentration of settlements along the dried up mythical Vedic river valley 'Saraswati', an extension of Ghaggar river in the Thar desert. Isotope and archaeological data suggest that the pre-Harappans started inhabiting this area along the mighty Ghaggar-Hakra rivers fed by intensified monsoon from 9 to 7 ka BP. The monsoon monotonically declined after 7 ka yet the settlements continued to survive from early to mature Harappan time. Our study suggests that other cause like change in subsistence strategy by shifting crop patterns rather than climate change was responsible for Harappan collapse.
Journal of Archaeological Science 27, 2000
A new method to isolate phosphate from bones for oxygen isotope analysis was deveJoped and tested. A graphite-reduction technique introduced by O'Neil et al. (1994; Israel Journal oI Earth Sciences 43,203-212) is much simpler and quicker than conventional f1uorination techniques and was refined in this study. Problems that may arise during the preparation of bone tissue with high organic content were solved by adding two steps of pre-treatment to remove organic substances before complete dissolution of the bone. The reproducibility of 1) 18 0 values is very good, not only for commercial silver phosphate (± 0'25%0) and synthetic hydroxyapatite (± 0'22%0) but also for modern and fossil bones with different degrees of preservation (± 0'16%0). Interlaboratory comparisons were made with NIST-120c, NIST-120b, and the University ofMichigan Standard-I. The values for all standards are in good agreement with values obtained both with conventionaJ f1uorination and the graphite-reduction method (1) 18 0 p : 21,7; 20•0; 12•2%0 versus SMOW, respectively). Additionally, the influence of consolidants on the preparation and oxygen isotope analysis was investigated. This investigation was deemed necessary, because fragile and brittle animal remains from archaeological and palaeontological sites are often preserved with these materials before sampIes can be taken for isotopic analysis. Modern and fossil bones of different degrees of preservation were treated with Mowilith, Shellac, Zaponlack, and Ponal, and subsequently, oxygen isotope analyses were performed in the normal way. No measurable effect of these consolidants was observed on the analyses for 1) 18 0 p. The new procedure has been successfully used to analyse oxygen isotope ratios of cattle and pig bones from Holocene archaeological sites in different climate zones. Calculations of the 1) 18 0 vaJues of meteoric water and of mean temperatures using the 1) 18 0 p values illustrate that isotopic compositions ofbones from these terrestrial mammals refleet the climatic conditions of their environment very precisely.
Minerals
Oxygen and carbon isotopes of well-preserved skeletal remains give relevant support to archaeological and environmental reconstructions. However, the preservation of the skeletal remains must be preliminarily checked. About twenty-five years ago, a diagnostic method based on the oxygen isotope ratio in the phosphate, δ(O18/O16)Ph, and carbonate, δ(O18/O16)Carb, of bioapatite of modern mammals was proposed: for well-preserved samples, the δ(O18/O16)Ph and δ(O18/O16)Carb should plot near the regression line δ(O18/O16)Ph on δ(O18/O16)Carb obtained for modern mammals. In the last twenty years, techniques of analysis have changed. In the past, BiPO4 or Ag3PO4 were precipitated from dissolved bioapatite and analysed with the fluorination technique, whereas at present, temperature reduction (HTR) in a glassy carbon reactor with CO release is commonly used. Taking into account the HTR technique, for some modern mammals, we report a new δ(O18/O16)Ph + 1 on δ(O18/O16)Carb + 1 regression line...
Quaternary Research, 2004
Oxygen isotope analysis was performed on enamel phosphate of mammalian teeth from archaeological sites Kalli Pachchhim and Dadupur in the central Ganga plain and Charda in the northern Ganga plain. The bulk oxygen isotopic compositions of enamel phosphate from third molars (M3) of Bos indicus individuals belonging to different cultural periods were used to understand the climatic changes during the past 3600 cal yr B.P. Oxygen isotope ratios indicate humid conditions around 3600 cal yr B.P., followed by a trend toward drier conditions until around 2800 cal yr B.P. Then from 2500 to 1500 cal yr B.P. there is a trend toward higher humidity, followed by the onset of a dry period around 1300 cal yr B.P. The study of intratooth y 18 O variations in teeth from different periods demonstrates that the monsoon seasonality was prominent. Spatial changes in the amount of annual rainfall are also reflected in the y 18 O values. Teeth derived from areas with intense rainfall have lighter isotope ratios compared to teeth from regions receiving less rain, but they show similar seasonal patterns. The long-term paleoclimatic variations reflected by fluctuations in bulk y 18 O p values from M3 teeth match well with the regional paleoenvironmental records and show a good correlation to the cultural changes that took place during this time span in Ganga plain.
… in Mass Spectrometry, 2008
Modern and fossil teeth record seasonal information on climate, diet, and migration through stable isotope compositions in enamel and dentine. Climatic signals such as seasonal variation in meteoric water isotopic composition can be recovered through a microscale histology-based sampling and isotopic analysis of enamel phosphate oxygen. The phosphate moiety in bioapatite is particularly resistant to post mortem diagenesis. In order to determine the phosphate oxygen isotope composition of enamel, phosphate must be chemically purified from other oxygen sources in the enamel lattice and matrix, mainly hydroxyl and carbonate ions, and trace quantities of organics.
Oxygen isotopic composition of fossil horse tooth phosphate as a record of continental paleoclimate
Palaeogeography, Palaeoclimatology, Palaeoecology, 1994
Oxygen isotopic, elemental, and X-ray data are presented for a suite of 24 fossil horse teeth from Nebraska ranging in age from 18.2 to 8.5 Ma, to test the use of 6180 of enamel phosphate (61SOeo4) as a quantitative record of continental climate. Modern equid teeth were analyzed to estimate a relationship between 61SOpo4 and environmental water. Multiple samples of seven different fossil species from Burge Quarry, a ~ 12 Ma attritional fossil deposit, indicate that diagenetic overprints exist but can be detected by decreased P concentration and increased crystatlinity relative to modern enamel. Isotopic variation for the pristine samples from Burge Quarry is-I-1.5%o (1~, n = 9), which may represent the resolution of the procedure within a stratigraphic horizon. There are no apparent correlations with body size, hypsodonty, or phylogeny. A range of 7%o in 61SOpo4 occurs over the 10 m.y. interval. A trend towards depleted 61SOpo~ of about 4%0 corresponds to a depletion of up to 6%0 in 61so of precipitation between 18.2 and 8.5 Ma, but the range of variation at Burge is large relative to the climate signal. Our results demonstrate that 61SOeo4 should be useful in quantitatively reconstructing Cenozoic continental paleoclimate on 10 6year timescales. Isotopic variation due to taphonomic bias and the terrestrial rock record will likely obscure higher-order climate signals.
Human tooth enamel carbon and oxygen stable isotope dataset from chalcolithic Inamgaon (India
Data in Brief, 2021
The tooth enamel from the human remains of ten archaeological individuals belonging to a chalcolithic site at Inamgaon, District Pune, Maharashtra, were analysed for stable carbon and oxygen isotope compositions. The human remains of the involved individuals come from three consecutive periods: Period I (160 0-140 0 BC; n = 2), Period II (140 0-10 0 0 BC; n = 4), and Period III (10 0 0-70 0 BC; n = 4). Enamel carbonate of twenty teeth (n = 20), two from each individual, were analysed to understand the inter-and intra-individual variations in isotope ratios across the three habitational periods. The acquired dataset will help in understanding isotope baseline values for the region in the prehistoric context. The subsequent research works in the region can reuse our data in collation with other datasets for comparative investigations.
Oxygen isotope variations of phosphate in mammalian bone and tooth enamel
Geochimica Et Cosmochimica Acta, 1995
About eighty specimens from ten different species of mammals, collected from different areas under different climatic and environmental conditions, were measured for the oxygen isotopic composition of their bone and tooth phosphate. The equations relating these values to the mean oxygen isotopic composition of local meteoric water were also derived. The same equation can be used for goats, roe-bucks, and mouflons, despite the biological differences among these species. Measurements were made on about fourty different specimens of rabbit and hare from Europe, Africa, and Canada, but in this case the data obtained clearly show no direct relationship between the oxygen isotopic composition of local meteoric water and the isotopic composition of the skeletal phosphate. However, there seems to be an inverse relationship between the relative humidity of the studied areas and the δ 18O(PO43−) of the skeletal phosphate, thus suggesting the use of fossil bones of these mammal species as recorders of palaeoenvironmental relative humidity. Finally, a new equation was derived for the isotopic scale for horses, on the basis of all the previous data and of a few newly obtained results.