罗湖1孔概况介绍

国家科学技术部和中国科学院联合支持的“中国大陆环境钻探计划”资助下, 2002 年 7 月在云南高原的鹤庆盆地实施了湖心钻探, 获得了 737.72 m连续湖泊沉积岩心。本次钻探首次在国内采用内衬管取心的方法，确保了岩心不受外力作用而发生扭曲、变形，全井取心率高达 96.7%。所获得的 665.83m 岩心除底部37m为河床沉积外，其余岩心全部为连续的湖相沉积，岩性为灰色、灰绿色、灰褐色粘土和粉沙质泥，层理清晰，是我国迄今为止最长之一，也是理想的研究环境演化的湖泊沉积岩心之一。钻孔岩心在岩性特征上表现为 3个大的沉积旋回: 下部 (665.83-372.66m)、中部 (372.66-195.45m) 和上部 (195.45.45-0m) 都是从含砾石泥沙层到粉砂质粘土和粘土的沉积旋回。 鹤庆盆地(26°27′~26°46′N, 100°08′~100°17′E)为一构造断陷盆地, 位于青藏高原东南边缘部位, 属滇西北横断山余脉. 盆地四周被高山环绕, 周围山峰海拔均在 2500m 以上, 紧邻鹤庆盆地的东西两侧是连续而较高峻的山地, 南面山地稍低, 而北面是相隔约40 km的玉龙雪山(5596m), 由此鹤庆盆地形成了一个完整的山间盆地. 盆地面积约 144 km2, 呈南北长条形展布, 与构造带走向一致, 南北长约 22km, 东西宽约5~10 km, 地势低平, 海拔2193~2240 m, 北高南低, 坡度约 1°~3°. 盆地四周有小溪、小河汇入, 中部低洼地积水形成草海, 现在湖水变浅. 盆地东部有发源于玉龙雪山的漾弓河自北向南流过, 出盆地后折向东流入金沙江, 成为金沙江水系。 盆地位于西南季风区, 夏季主要受来自孟加拉湾的暖湿气流影响, 冬季受南支西风急流控制, 另外还兼受青藏高原局地气候的影响, 因此具有夏暖湿、冬温干的气候特点。1月均温 8℃, 7月均温 21℃, 年均温 13.5℃. 1 月平均降水量 2.4 mm, 7月为 229.3 mm, 年降雨量在900~1000 mm之间, 主要集中在夏季, 占全年降雨量的 80%~90%。

The Heqing Basin (26°27′–26°46′N, 100°08′–100°17′E) is a structural fault basin in northwestern Yunnan Province, which is in southwestern China. The basin is located at the southeastern margin of the Tibetan Plateau and belongs to the Hengduan Mountains. The basin is surrounded by mountains that are higher than 2500 m a.s.l. Eastern and western mountains closely adjacent to the basin are higher and steeper than the southern ones, while on the northern side of the basin are the Yulong Mountains (5596 m a.s.l.), about 40 km from the basin. Thus, the Heqing Basin is a closed intermontane basin. The basin covers an area of c. 144 km2, is c. 22 km long from north to south and c. 5–10 km wide from east to west, and stretches narrowly from north to south consistent with the direction of the tectonic fault. The topography of the basin is low and flat, with an altitude of 2193–2240 mand a decreasing gradient of 1–3° from north to south. The basin receives water from streams and rivers around it. The Yanggong River, which lies in the eastern basin and originates in the Yulong Mountains, flows across the Heqing Basin from north to south and then flows out of the basin toward the east into the Jinsha River (Fig. 1). The Heqing Basin lies in the southwest Asian monsoon region affected mainly by the warm-humid airflow from the Indian Ocean and Bengal Bay in summer and by the south-branch westerly in winter and is also affected by the local climate of the Qinghai–Tibet Plateau. Thus, the climate of the Heqing region is warm-wet in summer and mild-dry in winter. The mean annual temperature in the basin is 13.5 °C, with average monthly temperatures in July and January of 21 °C and 8 °C, respectively. The average annual precipitation ranges from 900 to 1000 mm, with an average of 2.4 mm in January and 229.3 mm in July, and most of the precipitation is concentrated in summer, which has 80%–90% of the annual precipitation. The HQ drilling core lies in the southwest corner of Yunhe Town at the center of the Heqing Basin (26°33′43.1″ N, 100°10′14.2″ E) and the altitude of the surface sediments is 2190 m a.s.l. (Fig. 1). The 737.72-m-long core is composed of almost continuous lacustrine sediment, except for 17 m of conglomerates in the lowest part of the core. The core lithology is mostly green-grey and grey-brown mud or fine-sand mud. There is clear lamination through the whole core, with abundant plant debris and snail shells.