【摘要】 中亚黄土对研究亚洲内陆干旱化、亚洲粉尘来源、亚洲季风和西风环流变化以及两者在中亚相互作用历史均具有重要意义。中亚南部帕米尔高原不同地貌面上广泛发育有厚约1～2 m的风成黄土沉积,文章对高原东北部瓦恰盆地的两个黄土剖面进行了细颗粒石英光释光测年。结果表明,瓦恰盆地黄土样品石英光释光信号主要源于325℃热释光信号所对应陷阱电子,以快速组分为主。每个样品分别采用石英光释光信号标准生长曲线法(SGC)和全球石英光释光标准生长曲线法(gSGC)获得的等效剂量与其单测片再生剂量法(SAR)实测等效剂量值在误差范围内是一致的,说明SGC法与gSGC法适用于瓦恰盆地的黄土测年。两个剖面黄土样品石英SAR法光释光年龄界于4.7～14.3 ka,沉积速率由早期的0.11 mm/a加速至全新世的0.15～0.18 mm/a。据沉积速率估算剖面1黄土堆积于17.2 ka至2.7 ka之间,主要堆积于末次冰盛期末至全新世晚期,且远比其所在地貌面要年轻。本研究为进一步开展帕米尔高原黄土古环境研究提供了年代框架。更多还原

【Abstract】 Loess deposited in Central Asia bears great significance for investigating the history of aridification in Inner Aisa, the provenance of Asian dust, the variation of Asian monsoon and the Westerly and their interplay. Aeolian loess deposits, with a thickness of 1 ～ 2 m, are widely deposited on the Pamir Plateau, which is located in the south of Central Asia. In this study, the chronology framework of two loess sections in Waqia Basin located in the northeast of Pamir Plateau is established by employing the fine-grained quartz(fgQ) luminescence dating technique.Section 1 loess(37°31′24″N, 75°39′59″E; elevation for 3782 m)is 1. 8 m thick and located on the top of glacialfluvial deposit on the south bank of Waqia River, 5 loess samples collected from this section. 26 km to the north of section 1,section 2 loess(37°34′47″N, 75°40′01″E; elevation for 3475 m) is 1. 2 m thick and deposited on the T3 terrace on the southwest bank of Waqia River, 3 loess samples collected from this section. The optically stimulated luminescence( OSL) signal of the fgQ is dominated by the fast component and originates from the electron traps responsible for the 325 ℃ thermoluminescence( TL) peak. The equivalent doses determined by using both the conventional standardized growth curve(SGC) and global standardized growth curve( gSGC) methods are consistent with each other within uncertainties, and it indicates that both two methods are applicable to loess deposits in Waqia Basin. The OSL ages determined by single aliquot regenerative( SAR) dose protocol suggest that the aeolian dust is deposited between 14. 3 ka and 4. 7 ka for these two sections. The sedimentation rate increases from0. 11 mm/a at the early stage to 0. 15～0. 18 mm/a during the Holocene. According to the accumulation rate, the section 1 loess is deposited between 17. 2 ka and 2.7 ka, mainly from the late glacial to Late Holocene, much younger than the surface it deposited. This study provides a preliminary chronological framework for reconstructing the paleoenvironment by using loess deposited on the Pamir Plateau.更多还原