沙漠成因及演變

1、會計(jì)學(xué)1沙漠成因及演變沙漠成因及演變l 河成說：河成說：俄B.A.奧布魯切夫，與康申理論相反，運(yùn)用地層與地貌比較方法研究認(rèn)為，卡拉庫姆沙漠由于古阿姆河沖擊作用的結(jié)果。后被其他學(xué)者證實(shí)。李?；舴遥≧ichthofen，F(xiàn)erdinand von，18331905年）， 局限性：上述假說均針對某一區(qū)域、某一范圍局限性：上述假說均針對某一區(qū)域、某一范圍而提出。實(shí)際沙漠成因非常復(fù)雜，很難用一種而提出。實(shí)際沙漠成因非常復(fù)雜，很難用一種理論或假說概括理論或假說概括地帶性干旱地帶性干旱 非地帶性干旱非地帶性干旱 1.1.干旱氣候與沙漠干旱氣候與沙漠海風(fēng)向背：極地、赤道氣候穩(wěn)定；中緯度地區(qū)，撒哈拉部分地區(qū)東北

2、信風(fēng)控制、華南海洋性氣候。非地帶性干旱非地帶性干旱 非地帶性干旱非地帶性干旱 1.1.干旱氣候與沙漠干旱氣候與沙漠洋流影響：大陸東側(cè)暖流、西側(cè)寒流加利福尼亞沙漠、秘魯、智利南部沿海沙漠、南非西海岸和北非沙漠。1.1.干旱氣候與沙漠干旱氣候與沙漠地形影響：雨影沙漠。智利、秘魯沙漠非地帶性干旱非地帶性干旱 Aeolian activity prevailed before 8.3 ka, and a unified Ulan Buh Paleolake containing the modern Jilantai Salt Lake covered the northern desert duri

3、ng 7.87.1 ka ago. The paleolake shrank and broke apart after 6.5 ka ago. Thereafter, the paleolake evolved into the modern UBD and Jilantai Salt Lake. The Ulan Buh desertlake evolution was likely due to the climate changes in the monsoon-influenced region during the earlymiddle Holocene （11500）.Zhao

4、 et al. Palaeogeography, Palaeoclimatology, Palaeoecology 331 332 (2012) 3138Sedimentary analysis reveals that continuous eolian sand started by 0.9 Ma, marking the initial formation of theTengger Desert; and the domination of eolian sand in the strata with similar characters of the modern desert ap

5、peared by 0.68 Ma, indicating expansion of the Tengger Desert. Our analysis suggests the uplift of Tibetan Plateau in the mid-Pleistocene probably played the main role for this drying event and desert formation, while global cooling may strength the arid environment of the proximal deserts.Li et al.

6、 Quaternary Science Reviews 85 (2014) 85-98Figure 1D indicates that initiation of windblown silt accumulation at Sanju occurred at 5.3 Ma, suggesting shifting sand dunes prevailed in the Tarim Basin by at least 5.3 Ma ago, as they do today.Sun et al. Science 312（2006）1621HunshandakeA study documente

7、d a threshold event ca. 4,200 years ago in the Hunshandake Sandy Lands of Inner Mongolia, northern China, associated with groundwater capture by the Xilamulun River. This process initiated a sudden and irreversible region-wide hydrologic event that exacerbated the desertification of the Hunshandake,

8、 resulting in post-Humid Period mass migration of northern Chinas Neolithic cultures. The research suggested Chinese civilization maybe rooted in the marginal areas in the north, rather than in the middle reaches of the Yellow River.Yang et al. PNAS 112 (2015)702706 Xilamulun River地帶性干旱地帶性干旱 Figure 1D indicates that initiation of windblown silt accumulation at Sanju occurred at 5.3 Ma, su