江北砾岩的砾组分析及其测年表明,重庆北碚西师附中剖面的江北砾岩在24.3 kaB.P.至10 kaB.P.期间,总体经历了细→粗→细两个沉积旋回。具体又可以细分为了7个小的粗→细的沉积旋回,在此基础上还叠加了更多更小尺度的粗、细变化,推测这些砾度的变化主要与气候干湿的频繁波动有关。研究发现重庆及其上游地区在24.3 kaB.P.至10kaB.P.期间爆发了7次古洪水,其中22.5 kaB.P.前后沉积了长轴为31 cm的砾石,由此推算此时的古洪水量达到约119 690.783 m3.s-1,为特大洪水量级,表明当时的水动力相当强;重庆及其上游地区在该时期降水强度达到最大,但是该层的厚度较小,推测此次强降水过程时间较短。研究认为,由于砾度有7次粗→细的过程,因此在24.3 kaB.P.至10 kaB.P.期间,重庆及其上游地区应该经历了7次降水多→少的过程,显示了24.3 kaB.P.至10 kaB.P.期间重庆及其上游地区降水强度变化较大。在相对湿润期降水充沛,河流水动力较强,更大砾径的砾石被洪水带至河漫滩或边滩沉积;反之在相对干旱期降水较少,河流水动力较弱,能被带至该地沉积的砾石砾径相对较小,许多细粒砂被带至此地沉积从而在砾岩中形成了许多砂岩或砂砾互层。 The gravel assemblages and their dating in Jiangbei conglomerate show that during the period from 24.3 kaB.P. to 10 kaB.P., the Jiangbei conglomerate in the middle section of Beishi West Beitiao Chongqing Municipality generally experienced two sedimentary cycles of fine → coarse → fine. Specifically, they can be subdivided into seven small and thin sedimentary cycles. Based on this, more and smaller scales of coarse and fine changes are superimposed. It is speculated that the changes of these gravelities are mainly related to the frequent fluctuations of climate wet and dry . The study found that seven ancient floods occurred between 24.3 kaB.P. and 10 kaB.P. in Chongqing and its upper reaches, of which 31 cm long-long gravel was deposited before and after 22.5 kaB.P. The flood volume reached about 119 690.783 m3.s-1, which is a very large flood level, indicating that hydrodynamic power at that time was quite strong. In Chongqing and its upstream areas, precipitation intensity reached the maximum during this period, but the thickness of this layer was small. Heavy precipitation process time is shorter. The study shows that due to the seven coarse → thin processes of gravel, during the period of 24.3 kaB.P. to 10 kaB.P., Chongqing and its upper reaches should undergo seven more → → less precipitation processes, indicating that 24.3 Precipitation intensity in Chongqing and its upper reaches varied greatly from kaB.P. to 10 kaB.P. In the relatively humid period, abundant rainfall, strong hydrodynamic river, larger gravel diameter of the gravel was flood to floodplain or edge beach deposition; the contrary, relatively less precipitation in the relatively dry period, the river hydrodynamic weak, can be brought to the ground The gravel gravel deposited is relatively small and many fine grained sand is deposited there to form interbedded layers of sandstone or gravel in conglomerates.