A new method for high-precision measurements of stable (δ88/86Sr) and radiogenic (87Sr/86Sr) Sr isotope ratios was developed on the MC-ICP-MS using a standard-sample-standard bracketing protocol. By carefully monitor...A new method for high-precision measurements of stable (δ88/86Sr) and radiogenic (87Sr/86Sr) Sr isotope ratios was developed on the MC-ICP-MS using a standard-sample-standard bracketing protocol. By carefully monitoring and controlling the accumulation of the on-peak backgrounds (i.e. the carryover memory) on the instrument, our method can provide an external precision of around 0.010‰ to 0.014‰ for 88/86 Sr measurements. Such precision is comparable to that achieved by double-spike TIMS method (DS-TIMS), and 2-3 times better than those of the previously reported results by MC-ICP-MS without spiking. The results of the standard seawater IAPSO are also identical to those by DS-TIMS. However, our method is more advantageous, efficient and convenient to use for routine Sr isotopic analysis than the DS-TIMS method as there is no need to prepare and calibrate the 84Sr-87 Sr double spike. Using this method, we measured the δ88/86Sr values in a series of international geological rock standards, which show large variability, with the lowest value (0.20‰) registered in JG-2, a terrestrial granite, and the highest value (0.539‰) in UB-N, a serpentinite. This may provide an additional means for isotopic characterization of geological processes, adding a new dimension over the traditional use of radiogenic Sr isotopic ratio 87Sr/86Sr.展开更多
The Erlitou site is located at Yanshi City,Henan Province.This site is a large settlement site of Erlitou culture,and it is dated to 3800-3500 a BP.Five kinds of domestic animals,i.e.,dogs,pigs,sheep,goats,and cattle ...The Erlitou site is located at Yanshi City,Henan Province.This site is a large settlement site of Erlitou culture,and it is dated to 3800-3500 a BP.Five kinds of domestic animals,i.e.,dogs,pigs,sheep,goats,and cattle were found from the site.In this paper,two problems have emerged in studies involving the estimation of local isotope levels and the distinction of migrants from locals.Tooth enamel samples from 17 domestic animals individuals were analyzed for strontium isotope ratio(87Sr/86Sr),by the thermal ionization mass spectrometry,including 10 pigs,5 sheep and 2 cattle.The results show that the mean 87Sr/86Sr ratios of 10 pigs enamel samples were 0.712078,Based on the local strontium isotopes ratio range determined by the mean 87Sr/86Sr ratios ±2 of 10 pig enamel samples(0.712256-0.711900),we found that five sheep and one cattle from the Erlitou site fell well outside the local strontium isotopes ratio range and were considered to be non-local.展开更多
The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widel...The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widely. These disputations among researchers were caused mainly by timeframe selection （sections＇ thickness or data of radiometric ages）, and different stratigraphic boundaries and un-upmost dated ages. This paper examined published ^87Sr/^86Sr data of the Lopingian, and projected them on timescales based on evolutionary and age constrained conodonts fossils. ^87Sr/^86Sr evolution vs fossil constraining timescales was re-established in this period. This research suggests： （1） ^87Sr/^86Sr excursion projects on fossil zones can truly support ^87Sr/^86Sr evolutionary pattern in the period; （2） ^87Sr/^86Sr evolution provides a new approach for stratigraphic research of marine carbonate sections in lieu of biostratigraphic data; （3） ^87Sr/^86Sr stratigraphy works on marine carbonate sections of different sedimentation rates even between different basins; （4） the ^875r/^86Sr data and its shift was dependent on samples materials and chemical treatment methods; （5） the increasing rate of marine water ^875r/^86Sr in the Late Permian is suggested as 5.4× 10^-5/Ma or slightly lower; （6） sedimentation age and its ^875r/^86Sr of the Lopingian marine carbonate suggested as： Dpro=259-（Rs- 0.70695）/5.4×10^-5 （Ma）.展开更多
基金supported by the Chinese Ministry of Science and Technology Special Scheme (2009CB421206 and 2010CB808900)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-138)+1 种基金the National Natural Science Foundation of China (40973008 and 41173006)contribution No.IS-1616 from GIGCAS
文摘A new method for high-precision measurements of stable (δ88/86Sr) and radiogenic (87Sr/86Sr) Sr isotope ratios was developed on the MC-ICP-MS using a standard-sample-standard bracketing protocol. By carefully monitoring and controlling the accumulation of the on-peak backgrounds (i.e. the carryover memory) on the instrument, our method can provide an external precision of around 0.010‰ to 0.014‰ for 88/86 Sr measurements. Such precision is comparable to that achieved by double-spike TIMS method (DS-TIMS), and 2-3 times better than those of the previously reported results by MC-ICP-MS without spiking. The results of the standard seawater IAPSO are also identical to those by DS-TIMS. However, our method is more advantageous, efficient and convenient to use for routine Sr isotopic analysis than the DS-TIMS method as there is no need to prepare and calibrate the 84Sr-87 Sr double spike. Using this method, we measured the δ88/86Sr values in a series of international geological rock standards, which show large variability, with the lowest value (0.20‰) registered in JG-2, a terrestrial granite, and the highest value (0.539‰) in UB-N, a serpentinite. This may provide an additional means for isotopic characterization of geological processes, adding a new dimension over the traditional use of radiogenic Sr isotopic ratio 87Sr/86Sr.
基金supported by National Science and Tech-nology Program of China (Grant No.2006BAK21B03)
文摘The Erlitou site is located at Yanshi City,Henan Province.This site is a large settlement site of Erlitou culture,and it is dated to 3800-3500 a BP.Five kinds of domestic animals,i.e.,dogs,pigs,sheep,goats,and cattle were found from the site.In this paper,two problems have emerged in studies involving the estimation of local isotope levels and the distinction of migrants from locals.Tooth enamel samples from 17 domestic animals individuals were analyzed for strontium isotope ratio(87Sr/86Sr),by the thermal ionization mass spectrometry,including 10 pigs,5 sheep and 2 cattle.The results show that the mean 87Sr/86Sr ratios of 10 pigs enamel samples were 0.712078,Based on the local strontium isotopes ratio range determined by the mean 87Sr/86Sr ratios ±2 of 10 pig enamel samples(0.712256-0.711900),we found that five sheep and one cattle from the Erlitou site fell well outside the local strontium isotopes ratio range and were considered to be non-local.
基金This research was supported by National Basic Research Program of China （Grant No. 2011CB808905）, National Natural Science Foundation of China （Grant Nos. 41227801, 41273004, and 412003028）, Knowledge Innovation Program of the Chinese Academy of Sciences （Grant No. KZCW2-YW-Q08-4） and Instrument Developing Project of the Chinese Academy of Sciences （Grant No. YZ201433）. We thank anonymous reviewers for their generous helps to improve the manuscript, and also appreciate members of experimental paleontology research group for their stimulating discussions and constructive suggestions.
文摘The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widely. These disputations among researchers were caused mainly by timeframe selection （sections＇ thickness or data of radiometric ages）, and different stratigraphic boundaries and un-upmost dated ages. This paper examined published ^87Sr/^86Sr data of the Lopingian, and projected them on timescales based on evolutionary and age constrained conodonts fossils. ^87Sr/^86Sr evolution vs fossil constraining timescales was re-established in this period. This research suggests： （1） ^87Sr/^86Sr excursion projects on fossil zones can truly support ^87Sr/^86Sr evolutionary pattern in the period; （2） ^87Sr/^86Sr evolution provides a new approach for stratigraphic research of marine carbonate sections in lieu of biostratigraphic data; （3） ^87Sr/^86Sr stratigraphy works on marine carbonate sections of different sedimentation rates even between different basins; （4） the ^875r/^86Sr data and its shift was dependent on samples materials and chemical treatment methods; （5） the increasing rate of marine water ^875r/^86Sr in the Late Permian is suggested as 5.4× 10^-5/Ma or slightly lower; （6） sedimentation age and its ^875r/^86Sr of the Lopingian marine carbonate suggested as： Dpro=259-（Rs- 0.70695）/5.4×10^-5 （Ma）.
