Thermoluminescence dating of the orkutsay loess section in Tashkent region, Uzbekistan, Central Asia
Thermoluminescence dating of the orkutsay loess section in Tashkent region, Uzbekistan, Central Asia
复制标题
DOI：
10.1016/0277-3791(95)00056-9
复制
发表时间：
1995
影响因子：
4
通讯作者：
L. Zhou;A. Dodonov;N. Shackleton
中科院分区：
文献类型：
--
作者：
L. Zhou;A. Dodonov;N. Shackleton
20世纪70年代，中亚黄土的年代学研究采用了热释光测年（TL）方法，当时的年代估计范围从20 ka到800 ka以上。这对中亚黄土地层学和古气候重建造成了重大误解。我们提出了一个新的热释光研究的黄土剖面在乌兹别克斯坦的塔什干地区的Orkutsay。9个样品分布在一个大的地层间隔产生明显的TL年龄范围从20万年到134万年。我们解释我们的热释光结果参考最近的热释光测年研究黄土从其他地区。我们认为我们的TL年龄估计再生方法被低估。一个单一的TL年龄为92.8 ka的总漂白法获得的黄土下面的第一个pedocomplex（PC 1）的末次间冰期也显着年轻于预期。我们把这种低估归因于实验室光漂白引起的灵敏度变化和TL信号的不稳定性。我们的结论是，目前的TL技术在这项研究中所采用的不能提供一个可靠的绝对年代PC 1以下的序列，甚至不能提供一个相对年代PC 2以下的黄土。对于Orkutsay部分，测年极限约为130 ka。本研究结果表明，以前的中亚黄土年代学的基础上早期TL研究是不成立的。
The chronology of loess in Central Asia was investigated by means of thermoluminescence dating (TL) in the 1970s, when age estimates ranging from 20 ka to over 800 ka were taken as providing an absolute chronology. This has caused major misinterpretation of Central Asian loess stratigraphy and palaeoclimatic reconstruction. We present a new TL study of a loess section at Orkutsay in the Tashkent Region, Uzbekistan. Nine samples spreading over a large stratigraphic interval yield apparent TL ages ranging from 20 ka to 134 ka. We interpret our TL results with reference to recent TL dating studies of loess from other regions. We consider most of our TL age estimates obtained by the regeneration method to be underestimated. A single TL date of 92.8 ka obtained by the total bleach method for loess just below the first pedocomplex (PC 1) of the last interglacial is also significantly younger than expected. We attribute the underestimation to sensitivity change induced by the laboratory optical bleach and instability of the TL signal. We conclude that the current TL techniques as employed in this study cannot provide a reliable absolute chronology for the sequence below PC 1 and cannot provide even a relative chronology for the loess below PC2. For the Orkutsay section the dating limit is around 130 ka. The results of this study suggest that the previous Central Asian loess chronology based on early TL studies is not valid.