年层石笋记录的华北倒三冰期终止期的起始时间和精细结构

自深海氧同位素记录发表以来，冰期终止期的驱动问题就争议不断。近年来发表的具有精确年代控制的中国南方石笋记录跨越了最近6个完整的冰期旋回，为分析冰期终止机理提供了新的年代框架。其中倒三冰期终止期（T-III）与末次冰期终止期（T-I）气候模式最为相似，但也存在细节差异。迄今为止，为数不多的关于T-III的石笋记录都在北纬35度以南，它们记录的千年尺度气候事件的精细结构仍存在显著差异。因此，要能全面了解T-III在不同区域的气候变化模式及T-III与T-I的异同，我们亟需获得中国北方T-III精细结构的记录。申请者获取的北京苦栗树洞的两根可衔接的方解石类石笋几乎跨完整T-III时段，铀系年代精度优于1%，两根石笋都发育清晰年层，无明显沉积间断。因此可以建立精确时标控制的华北T-III高分辨石笋同位素记录，通过年层计数精细刻画该时段千年事件结构，为理解冰期旋回及千年气候波动的成因提供关键证据。

The drive of Ice Age Terminations has long been controversial since the oxygen isotope ratio (δ18O) measurements on marine sediments. In the past few years, the stalagmite record from southern China has established the last 6 ice age cycles with exact timing control, which supplies a new time scale to explore the forcing of terminations. The climate patterns during the antepenult (T-III) and the last (T-I) is largely consistent. Nevertheless, there are still some obvious differences between them in detail. Additionally, the few available stalagmite records covering T-III are all from south of 35 degrees north latitude and the detailed structures of millennial-scale climate changes documented in them are not always consistent. Thus, to fully understand the climate patterns during T-III in various areas and also the similarities and differences during T-III and T-I, we should get the corresponding stalagmite records in northern China. Here we propose the two calcite-stalagmites from Kulishu Cave in Beijing, northern China, which cover most portions of T-III. The preliminary analysis indicates that the precisions of the uranium series dating are better than 1% and both of the stalagmites have very clear laminae with no hiatus. Accordingly, we can establish the high-resolution stable isotope series controlled by precise time scale and then depict the detailed structures of T-III in northern China by laminae-counting. This work will provide a new critical evidence to understand the drives of ice age cycles and the millennial-scale oscillations within them.