水平总梯度法在化探异常圈定中的应用:以青海省某地区1∶5万水系沉积物地球化学测量为例

Application of Horizontal Total Gradient Method in Geochemical Exploration Anomaly Setting: The Geochemical Survey of 1∶50 000 Water Sediments in a Certain Area of Qinghai Province as an Example

由于不同地质环境背景值的差异,单纯通过成矿元素含量的差异圈定异常,可能会忽略低值异常和放大高值异常,造成异常与已知矿床不对应的现象。地球化学场是一个连续、可导的场,通过一阶梯度分析可以将不同含量范围的元素含量变化率反映出来,更接近真实的异常情况。以青海省某地区1∶5万水系沉积物测量数据为研究对象,运用水平总梯度法将研究区4107个原始数据进行梯度分析,绘制出Cu、Pb、Zn、Ag单元素水平总梯度异常图,通过与传统方法进行对比,发现水平总梯度法可以将传统方法所忽略的离散、不成规模的小异常更好地呈现出来,而且圈定的异常结果分带性更好,浓集级数变高,浓集中心突出,异常更加明确,与已知的矿床(点)吻合程度更好。因此,水平总梯度法能更好地反映异常信息,比较准确地圈定异常区域,具有很好的应用前景。

Due to the difference in the background values of different geological environments, the determination of abnormalty simply by the difference in the content of ore-forming elements may lead to the ignorance of the abnormalities of low-value anomalies and high-magnification anomalies. This may result in the incorrespondance of anomalies to theknown deposits. The geochemical field is a continuous, steerable field. Through a step analysis, the rate of change of element content in different content ranges can be reflected, which is closer to the real abnormal situation. This paper takes the measurement data of 1∶5 million water system sediments in a certain area of Qinghai Province as the research object and draws the gradient anomaly maps of Cu, Pb, Zn and Ag by gradient analysis. It is found that the horizontal total gradient method can discrete the traditional method. Small anomalies not large in scale are better presented, while the anomalous zoning is better, the concentration series becomes higher, the concentration center is prominent, and the degree of coincidence with known deposits is better. This shows that the horizontal total gradient method can better respond to abnormal information and accurately define the abnormal region, which has a good application prospect.