ABSTRACT

The Hunder Dunes occur in the Shyok valley, Ladakh region, north-western India. These barchanoid and transverse dunes consist of sand reworked from the seasonally exposed beds of the river. Wind direction is strongly uni-modal from the northwest and is controlled by valley orientation. We observed small (10–20 m long, 5–10 m wide, and up to 1.5 m high) ellipsoidal mesas in the swales between dunes, composed of sand deflated from the Shyok River system. The mesas have a tiered, wedding cake appearance with concave upper surfaces. We interpret these mesas as inverted swale deposits consisting of stacked cycles of sediment. The cycles range from 40 to 50 cm in thickness and are composed of a from bottom to top, deposits of prior dunes, high energy fluvial deposits with climbing ripples, pool sediments with symmetrical wave ripples, and desiccation-cracked mud drapes over the ripples indicating final drying out of the pool. Up to four cycles of deposition were present in the mesas. The inverted swales are being both exhumed from beneath and buried underneath migrating dunes. Inverted swale deposits provide a record of historical depositional processes and biological communities active at the site.

摘要

兴隆沙丘（Hunder Dunes）发生在印度西北部拉达克地区的Shyok山谷。这些沙丘和横沙丘由经季节性暴露的河床重修而成的沙子组成。风向从西北强烈呈单峰态，受谷向控制。我们在沙丘之间的小溪中观察到了小椭圆形台面（长10–20 m，宽5–10 m，最高1.5 m），椭圆形的台面由Shyok河水系排出的沙子组成。台面具有分层的婚礼蛋糕外观，并具有凹入的上表面。我们将这些台地解释为由堆积的沉积物循环组成的倒置的沼泽沉积物。循环的厚度从40到50厘米不等，由下至上，先有沙丘的沉积物，高能的河流沉积物（具有爬升的波纹），对称波状波纹的池沉积物，干裂的泥浆覆盖在涟漪上，表明游泳池最终干drying了。台面中存在多达四个沉积周期。倒立的鲸鱼既从沙丘下面挖出，又被埋在沙丘下。倒置的鲸鱼沉积物提供了该地点历史沉积过程和活跃的生物群落的记录。