沉积物的光释光测年和对沉积过程的指示意义

OPTICAL DATING OF SEDIMENTS FROM CHINA AND ITS IMPLICATION FOR DEPOSITIONAL PROCESSES

应用光释光测年技术测量了位于陕西、河南、湖北和安徽等地9个剖面的49个沉积物样品，这些样品的光释光信号都是以快组分为主，等效剂量预热坪区和剂量复原实验结果也表明这些样品都适合应用单片再生剂量法测量其等效剂量。根据测量的光释光年龄数据和样品的埋深，建立了各剖面的年龄一深度曲线和函数，通过它们推算出了各剖面的长期堆积速率，并据此指出了可能的沉积环境变化。在取样的深度范围内，所测剖面的堆积速率从0．02mm／a到2．58mm／a，并显示一般风成黄土的堆积速率要比水成堆积物的堆积速率要慢。所测样品的年龄从0．2±0．01ka到53．8±4．7ka。在9个剖面中，有两个自然剖面发生了长时期的沉积间断。在有文化层的剖面中，文化层下部地层的年代明显老于文化层和上部地层的年龄，文化层中沉积物的光释光年龄也可以用来指示文化层的堆积情况。另外，对两个剖面也进行了14C定年，结果显示沉积物全样的14C测年值得进一步研究。

In this paper,optical dating techniques were applied to date 49 samples from 9 localities in Shaanxi, Shanxi, Henan, Hubei, and Anhui provinces, China, and they are Tuqiaoliang section （ 37 ° 34′ 16.7″N, 109 ° 09′05.0″） , Taizitan section, Dayanghecunxi section （ 34°48′39.2″N, 112°24°31.5″E ） , Dayanghecun section （ 34°48 ′35.7″N, 112°24′41.0″E）,Wadian section （34°11′17.2″N, 113024° 17. 7″E）,Lingjiatan section （31°27′38. 9″N, 118°02′52.9″E ）, and Qujialing sections of QJL07-A （ 30°49′59.2″N, 112°54′09.3″E ）, QJL07-B （ 30050° 15.7″N, 112°54′09.3″E）, C DZC （30°48′18.4″N, 112°51′41.9″E ）. The luminescence properties of these samples such as their OSL signals dominated by fast component, preheat plateau and dose recovery tests show that they are suitable for equivalent dose measurements using the single-aliquot regeneration-dose protocol. Based on the optical ages obtained and the burial depth of dated samples, the age-depth curve and function were obtained for each section. The long-term accumulation rate for each section was calculated using the age-depth function, and the change in depositional environments was inferred for each locality based on the accumulation rate and optical ages. Within sampling depth, accumulation rate ranges from 0.02mm/a to 2. 58mm/a for these sections, and a significant erosional/depositional hiatus is identified for two natural sections. The optical ages of the dated samples range from 0.2 ±0.01ka to 53.8 ±4.7ka,and they are in stratigraphic order except for the section in Shanxi Province. This section was considered as rapidly deposited sediments. For sections interbedded with cultural layer,the sediments from the underlying sediments are too older than both the cultural layer and the overlying sediments. Furthermore, the optical ages of the sediments from the cultural layer also provide information for the accumulation of cultural deposits. In addition, radiocarbon dating was also carried out on two sections. The results show that the radiocarbon dating of bulk samples requires further investigation.