New advances in the study of Alpine glaciations

The European Alps is the birthplace of glaciology and in particular Quaternary glaciology and for over one hundred years has been a model region for studying mountain glaciations. In this paper, we review the achievements from this region, which will benefit glaciological studies of the Tibetan Plateau, China. According to new evidences of glaciofluvial de- posits discovered in valleys and forelands of the Alps, researchers have progressed from an original four Pleistocene gla- ciations to seven glaciations： Biber, Donua, Gtinz, Haslach, Mindel, Riss and WOrm. The earliest one Biber possibly oc- curred between the Pliocene and Pleistocene, but the chronology before Riss is still in doubt. Recent years, Riss and Wtirm glaciations have been supported by a large numbers of cosmogenic exposure dating. In particular, cosmogenic nuclide exposure dating has been carried out for different moraine boulders in numerous valleys, which reveals a series of climatic change events, and they are comparable to post-glacial age records of northern Europe. The advancement of glaciological studies in the Alps is important in promoting glaciological research in the Tibetan Plateau.

The morphological characteristics of glacial deposits during the Last Glaciation, taking the Parlung Zangbo River Basin as an example

Moraine morphology is a valuable indicator of climate change. The glacial deposits of ten valleys were selected in the Parlung Zangbo River Basin, southeastern Tibetan Plateau, to study the glacial characteristics of the Last Glaciation and the climate change processes as revealed by these moraines. Investigation revealed that a huge moraine ridge was formed by ancient glacier in the Marine Isotope Stage 2 （MIS2）, and this main moraine ridge indicates the longest sustained and stable climate. There are at least two smaller moraine ridges that are external extensions of or located at the bottom of the main moraine ridge, indicating that the climate of the glacial stage before MIS2 was severer but the duration was relatively shorter. This distribution may reflect the climate of MIS4 or MIS3b. The glacial valleys show multi-channel, small-scale moraine ridges between the contemporary glacial tongue and the main moraine ridge. Some of these multi-channel mo- raine ridges might be recessional moraine, indicating the significant glacial advance during the Younger Dryas or the Heinrich event. The moraine ridges of the Neoglaciation and the Little Ice Age are near the ends of the contemporary glaciers. Using high-precision system dating, we can fairly well reconstruct the pattern of climate change by studying the shape, extent, and scale characteristics of glacial deposits in southeastern Tibet. This is valuable research to understand the relationship between regional and global climate change.

阿拉善沙漠物源和输沙带研究进展及其对“三北”工程风沙口治理的启示

位于内蒙古西部的阿拉善高原分布着中国面积第二、第四大的巴丹吉林沙漠、腾格里沙漠,是中国北方粉尘的重要源区,也是西北路风沙进京的重要通道。这两大沙漠目前已被纳入新“三北”工程河西走廊-塔克拉玛干沙漠边缘阻击战的重点治理区域,斩断两大沙漠“握手”、锁边固沙是本区的治理难点。为了给“三北”工程风沙口治理和相关基础研究提供全面深入的参考,回顾了对两大沙漠物源和围绕雅布赖山形成的“握手”输沙带的重要研究进展,并提出了未来应围绕风沙源区和传输机制、锁边林草建设和防护林退化机制以及发挥风能资源优势等方面开展科研创新,以科技攻关带动“三北”工程攻坚,为打赢“三北”工程三大战役提供支撑。

“三北”工程山水林田湖草沙“皮”“毛”兼治的生态治理新理念

过去10年来,中国创造性提出并发展了山水林田湖草沙系统治理、综合治理、源头治理、全域治理等生态治理新理念,实现了从单一要素治理到多要素一体化治理、从九龙治水到流域统筹的转变。在“三北”等重点生态工程建设实践中,如何统筹土地要素(生态用地)和植被要素(生产力)的生态治理仍然存在困难。分析了山水林田湖草沙7类要素特征的独特性,提出“三北”工程山水林田湖草沙“皮”“毛”兼治的理念,介绍了“皮”“毛”兼治的典型区和典型案例,为未来沙区开展荒漠化综合防治和“三北”等重点生态工程建设提供了新的思考。

Impact Craters with Circular and Isolated Secondary Craters on the Continuous Secondaries Facies on the Moon

On airless bodies such as the Moon and Mercury, secondary craters on the continuous secondaries facies of fresh craters mostly occur in chains and clusters. They have very irregular shapes. Secondaries on the continuous secondaries facies of some Martian and Mercurian craters are more isolated from each other in distribution and are more circular in shape, probably due to the effect of target properties on the impact excavation process. This paper studies secondaries on the continuous secondaries facies of all fresh lunar complex craters using recently-obtained high resolution images. After a global search, we find that 3 impact craters and basins on the Moon have circular and isolated secondaries on the continuous secondaries facies similar to those on Mercury： the Orientale basin, the Antoniadi crater, and the Compton crater. The morphological differences between such special secondaries and typical lunar secondaries are quantitatively compared and analyzed. Our preliminary analyses suggest that the special secondaries were probably caused by high temperature gradients within the local targets when these craters and basins formed. The high-temperature of the targets could have affected the impact excavation process by causing higher ejection angles, giving rise to more scattered circular secondaries.

Evidence for glaciation predating MIS-6 in the eastern Nyainqêntanglha Range, southeastern Tibet

Southeastern Tibet is one of the most glaciated regions on the Tibetan Plateau both at present and during the Quaternary. Numerical dating of glacial deposits has allowed the establishment of a provisional chronology of Quaternary glacial fluctuations in this region, with the oldest glaciation(Guxiang Glaciation) occurring in marine oxygen isotope stage 6(MIS-6).During our recent field investigations, a morphostratigraphically older lateral moraine than that of the Guxiang Glaciation has been first identified, which is ~500–600 m above the Guxiang Glaciation moraine and discontinuously preserved on valley shoulders in the Bodui Zangbo River valley, eastern Nyainqêntanglha Range in southeastern Tibet. Considering the moraine is best preserved at Nitong Village, here we name the glacier advance which deposited the moraine as "Nitong Glaciation". Using electron spin resonance(ESR) technique, we dated the Nitong Glaciation moraine to 506.3±60.4 ka. Taking into account the age error and climatic conditions, we consider it most likely that the Nitong Glaciation occurred during MIS-12, although it might had happened sometime earlier.