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对山西娘子关绵河不同阶地上沉积的泉钙华进行了高精度的230Th定年和碳氧稳定同位素组成测定。结果发现,绵河II级阶地沉积的娘子关泉钙华的最老年龄在407～466ka,远老于早前通过钙华中的石英砂热发光法(TL)获得的年龄,即绵河II级阶地上的娘子关泉钙华是在中更新世MIS12/11阶段形成的,而非原来认为的是晚更新世的产物。由此推测,绵河III级阶地娘子关泉钙华形成的年代更早,可能是中更新世的MIS14/13阶段。230Th测年获得的绵河I级阶地顶部的钙华形成于5ka前,即是在全新世中期以前形成的。结合钙华规模及其碳氧稳定同位素组成分析进一步发现,上述绵河三级阶地上的娘子关泉钙华均主要是湿热气候下的产物。然而,自II级阶地钙华形成至今,气候总体上在向干冷方向发展,泉域植被则呈现退化的趋势。
High-precision 230Th dating and carbon-oxygen stable isotopic compositions of spring travertine deposited on different terraces in Niangziguan, Shanxi were carried out. The results showed that the oldest age of the Niangziguan spring travertine deposited in the Mianhe II terraces ranged from 407 to 466 ka, much older than that obtained from the quartz sand thermoluminescence (TL) The terrestrial Niangziguan Travertine was formed during the Middle Pleistocene MIS12 / 11, rather than the product of the late Pleistocene. It can be inferred that the formation of Mianzuan uplifting travertine in Mianhe III terrace is earlier in age, probably during MIS14 / 13 stage of Middle Pleistocene. The travertine formed at the top of the Mianhe I terrace in the 230Th dating was formed before 5 ka, which was formed before the mid-Holocene. Combined with the travertine scale and its carbon and oxygen stable isotopic composition analysis, it is further found that the Niangziguan Travertine on the third terrace of Mian River are mainly the products under moist and hot climates. However, since the formation of stage II travertines to the present, the climate generally develops in a dry and cool direction, and the vegetation in the spring area tends to degenerate.