粤北南雄和灯塔盆地“牛肝土”差异性发育的地质成因

Geological mechanism of differential development of“Niugantu”in Nanxiong and Dengta Basin,northern Guangdong Province

粤北地区牛肝土(红层荒漠化)是南方丘陵山地带所面临最突出的生态问题之一。本文通过遥感解译和地质调查验证的手段,对粤北南雄和灯塔盆地牛肝土的空间分布进行了分析。结果显示:南雄盆地牛肝土主要分布于白垩系—古新统的紫红色泥页岩和粉砂质泥岩中,色调突出、纹理清晰,具典型的“鸡爪沟”特征,其分布密度由盆地中心往两侧递减。灯塔盆地中未发现有明显的牛肝土出露,水土流失现象主要发育于白垩系红层和一套第四系的红色坡积物中。研究认为导致南雄和灯塔盆地中牛肝土和类牛肝土差异发育的地质因素可能与盆地岩性、沉积抬升历史、沉积物源差异以及新构造活动有关。研究结果可为粤北红层盆地中牛肝土的成因和生态修复提供基础资料。

The red layer desertification(Niugantu)in northern Guangdong Province is one of the most prominent ecological problems hilly and mountainous region of south China.Based on remote sensing interpretation and geological survey,the spatial distribution of Niugantu in Nanxiong and Dengta Basin(northern Guangdong Province)was analyzed.The results show that the Niugantu in Nanxiong Basin is mainly distributed in the Cretace-Palaeocene purplish red shale and silty mudstone,with prominent color and clear texture,and a typical"chicken's foot ditch"feature,and its distribution density decreases from the center of the basin to both sides.There is no obvi-ous exposure of Niugantu in Dengta Basin,and soil and water loss mainly develop in the red strata of Cretaceous and red slope deposits.It is concluded that the geological factors that lead to the differential development of Niugantu and Leiniugantu in Nanxiong and Dengta basins may be related to basin lithology,sedimentary uplift his-tory,sediment source differences and neo-tectonic activities.The results can provide basic data for the genesis and ecological restoration of Niugantu in the red bed basin of northern Guangdong Province.