Abstract. Hydroclimate changes have exerted a significant influence on the historical trajectory of ancient civilizations in arid Central Asia where the central routes of the Silk Road have been hosted. However, the climate changes on different timescales and their possible forcing mechanisms over the last millennium remain unclear due to low-resolution records. Here, we provide a continuous high-resolution humidity history in arid Central Asia over the past millennium based on the ∼1.8-year high-resolution multiproxy records with good chronological control from Lake Dalongchi in the central Tian Shan. Generally, the climate was dry during the Medieval Warm Period (MWP) and Current Warm Period (CWP) and wet during the Little Ice Age (LIA), which could be attributed to the influence of the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO). Furthermore, we find that the humidity oscillation was dramatic and unstable at multidecadal to century scales. Especially within the LIA, four wet episodes and three dry periods occurred. The continuous wavelet analysis and wavelet coherence show that the humidity oscillation is modulated by the Gleissberg cycle at the century scale and by the quasi-regular period of El Niño–Southern Oscillation (ENSO) at the multidecadal scale. Our findings suggest that the effect of the solar cycle and the quasi-regular period of ENSO should be seriously evaluated for hydroclimate predictions and climate simulations in arid Central Asia in the future.

<p>The 1500-km-long Kunlun strike-slip fault is one of the largest and most active faults in the Tibetan Plateau. The eastward extrusion of Tibet has generated the 2001 Mw 7.8 Kunlunshan earthquake along the eastern Kunlun fault (elevation ≥ 4500 m) that produced the longest surface rupture yet recorded on land, ~400 km. The knowledge of past earthquake history and long-term fault behavior along the eastern Kunlun fault is still limited by short seismological records. Moreover, suitable sites for paleoseismological trenching are rarely available due to the active freeze-thaw action in such an extreme environment. Lacustrine paleoseismology, exploits lacustrine sediments to retrieve a much longer record of paleoseismic shaking, may shed light on earthquake occurrence and fault behavior along the eastern Kunlun fault.</p> <p>Lake Kusai is bounded by the eastern Kunlun fault in the north, and its north end was once ruptured by the 2001 Mw 7.8 Kunlunshan earthquake. Sedimentary sequence from the lake is characterized by layered sediments, thus an ideal site for lacustrine paleoseismology investigation. A 8.2 m-long core has been drilled from the lake in 2006. <sup>210</sup>Pb/<sup>137</sup>Cs and AMS<sup>14</sup>C dating, and detailed varve counting confirm that the upper 165 cm of the drilled sedimentary sequence is varved and spans the last 2000 years. This sedimentary sequence is therefore ideal for event deposits recognition and high-resolution seismic record reconstruction. We identify sedimentary imprint of the 2001 Mw 7.8 earthquake and another 13 deeper horizons of <em>in situ</em> soft sediment deformations and micro-faults from the sedimentary sequence. The primary data reveals a clustered earthquake recurrence pattern with a mean recurrence interval of ~150 years on the central part of the eastern Kunlun fault.</p> <p> </p> <p><strong>Keywords:</strong> Eastern Kunlun fault; Northern Tibetan Plateau; Lake Kusai; Varved lake sediment; Soft sediment deformation structure; Paleoseismic events.</p>

Climate changes on different timescales and their mechanisms are of great importance in arid Central Asia (ACA). However, the contribution of El Niño−Southern Oscillation (ENSO) to Holocene hydroclimate in ACA on centennial and millennial timescales is limited by records with good age control and high temporal resolution. Here, we present high-resolution X-ray fluorescence (XRF) scanning data of a sediment core from Lake Xiaolongchi in central Tianshan Mountains to reconstruct hydroclimate changes in ACA over the last 8000 years. Our construction exhibits that the climate was dry from 8000 to 5500 cal year BP and wet from 5500 to 0 cal year BP, which resembles ENSO patterns on a millennial timescale. On the centennial timescale, hydroclimate fluctuations with eight wet periods, seven dry periods, and a shift period have a significant 800-year periodicity, coincident with periodic ENSO variance. The positive relationship between 800-year band-pass filtered hydroclimate and ENSO indicates that wet (dry) climate conditions correspond to increased (reduced) ENSO activity. We propose that the spatial pattern of “wet (dry) southern China and ACA, and dry (wet) northern China” during the El Niño-like (La Niña-like) condition may exist during the Holocene on millennial to centennial timescales.

No abstract