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We present a crustal thickness and Vp/Vs map of Northeast and North China based on a compilation of receiver function H-k analysis published in the literature. Our compilation shows that the crust in the area has an average thickness of 35.9±5 km. The thinnest crust is found in the eastern and southern flank of the Songliao Basin (28∼35 km), North China plain and Songliao Basin (30∼35 km), while the thickest crust is found in the Yanshan-Taihang orogon and Ordos basin (40∼55 km). The average crustal Vp/Vs ratio is about 1.76±0.05 for the North China and Northeast China region, which maybe related with the lithospheric thinning in the eastern China. The highest Vp/Vs (> 1.83) are found in the Shanxi garben, Changbai Volocno and Zhangjiakou-Datong, indicating high ambient crustal temperatures or wide-spread intra-crustal melting. The existence of anticorrelation between Vp/Vs and the crustal thickness for Da Hinggan Ling area maybe related with tectonic thicken of felsic crust. No clear correlation is observed between the crustal thickness and Vp/Vs for Songliao basin and adjacent area, implying that complex tectonic evolution process took place in Songliao basin.

Lithium separation technique for three reference materials has been established together with precise determination of lithium isotope using a Neptune multi collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). The solutions of lithium element standard reference materials, potassium, calcium, sodium, magnesium and iron single element, were used to evaluate analytical methods applied. Three separate stages of ion-exchange chromatography were carried out using organic cation-exchange resin (AG 50W-X8). Lithium was enriched for the three stages using different eluants, which are 2.8 M HCl, 0.15 M HCl and 0.5 M HCl in 30% ethanol, respectively. The columns for the first and second stages are made of polypropylene, and those for the third stage are made of quartz. Total reagent volume for the entire chemical process was 35 mL for three reference materials. The recovery yielded for the three stages is 98.9-101.2% with an average of 100.0%, 97.6-101.9% with an average of 99.9%, and 99.8-103.3% with an average of 100.6%, respectively. The precision of this technique is conservatively estimated to be ±0.72-1.04‰ (2σ population), which is similar to the precision obtained by different authors in different laboratories with MC-ICP-MS. The δ7 Li values ( 7 Li/ 6 Li relative to the IRMM-016 standard) determined for andesite (AGV-2) and basalt (BHVO-2) are 5.68‰ (n=18), 4.33‰ (n=18), respectively. The δ7 Li value ( 7Li/6Li relative to the L-SVEC standard) determined for IRMM-016 is -0.01‰ (n=15). All these analytical results are in good agreement with those previously reported. In addition, the results for the same kinds of samples analyzed at the MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, are consistent with those obtained at the Plasma Laboratory, University of Maryland, within analytical uncertainty. According to these experiment results, it is concluded that this proposed procedure is a suitable method for determining the lithium isotopic composition of natural samples.