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在位于川滇菱形地块的西昌西南大德里向斜两翼的白垩系红色砂岩内采集古地磁学定向样品９６个（１２个采点），进行了古地磁学研究．研究结果表明，西昌晚白垩世末期的古地磁偏角为５．９°，古地磁倾角为４５．８°，古地磁极位置为北纬８４．７°，东径１９３．３°．将该数据与作者前期研究结果对比，则可见自楚雄至元谋，进而至西昌，其古地磁偏角逐渐靠近正北，而古地磁极纬度渐次升高．这反映了川滇菱形地块内的断块呈自西南至东北逐渐减弱的顺时针旋转特征，而这一古地磁学特征又揭示了川滇菱形地块断裂的右行走滑性质．
In the Cretaceous red sandstone located in the syncline of Dadili, Xichang, located in the Sichuan-Yunnan rhombus block, 96 samples (12 sampling points) of paleomagnetic geology were collected for paleomagnetic study. The results show that the paleomagnetic declination angle is 5.9 ° in the late Cretaceous of Xichang, the dip angle of paleomagnetic dip is 45.8 °, the paleomagnetic pole position is 84.7 ° N and the east diameter is 193.3 °. Comparing this data with the author's previous research results, it can be seen that from Chuxiong to Yuanmou and then to Xichang, the declination angle of paleomagnetic declination gradually approaches the north while the paleomagnetic pole latitude gradually increases. This shows that the fault block in the Sichuan-Yunnan rhombic block has a clockwise rotation feature that gradually weakened from southwest to northeast, and this paleomagnetic feature reveals the right-lateral slip fault of the Sichuan-Yunnan rhombic block fault.