摘要
对重磁资料进行综合处理与解释有助于降低多解性、提高解释的可靠性。重磁对应分析法是重磁联合定性解释的一种常用方法,但该方法会受剩磁影响,易产生虚假信息,因而实用性不强。为此,从重力异常二阶垂向导数与归一化磁源强度表达式出发,推导出基于重力二阶垂向导数和归一化磁源强度的重磁泊松公式,提出了一种新的重磁相关性分析方法,并采用噪声扰动提高重磁相关度的有效性。该方法物理意义明确,易于实现,无需化极处理,且受重磁背景场影响小。模型试验表明,常规重磁对应分析法仅在噪声扰动下重磁完全同源时具有良好效果,在重磁非完全同源时会出现虚假信息;新方法能够较好地反映重磁是否同源及同源位置,在复杂情况下也能获得良好的效果。将新方法应用于江西相山铀矿田重磁资料处理和解释,准确地反映了碎斑熔岩、流纹英安岩及花岗斑岩这三类重磁同源性岩石的位置及规模。另外,依据大面积分布的强负相关与强正相关特征推测了古火山喷发的主要岩石类型,并预测了一个碎斑熔岩火山口。同时,相山地区铀矿点主要分布在强正相关与强负相关的过渡带上,进一步揭示了铀矿分布与岩性接触面存在着密切关系。这些研究成果可为相山地区深部铀矿勘查提供数据基础。
Comprehensive processing and interpretation of gravity and magnetic data can be employed to reduce multi⁃solutions and improve geological interpretation reliability.The gravity and magnetic correspondence analysis method is a commonly adopted method for joint quantitative interpretation of gravity and magnetic anomalies.However,the method is affected by remanent magnetization to cause spurious information,and thus the practicality is low.Therefore,this paper derives Poisson’s formula of gravity and magnetic anomalies based on the expressions of the second⁃order vertical derivative of gravity anomaly and normalized source strength of magnetic anomaly.Additionally,a new gravity and magnetic correspondence analysis is proposed,and the effectiveness of the new method can be improved through noise disturbance.This method features clear physical meaning,easy implementation,and no need for reduction to the magnetic pole,and it is less influenced by the background field of gravity and magnetics.The model tests show that the conventional correspondence analysis method only yields sound results when the gravity and magnetics are totally the same source,and spurious information will be produced when the gravity and magnetic sources are different.The proposed method can reflect whether the gravity and magnetic sources are the same source and location and can obtain good results under complex situations.Meanwhile,by applying the new method to pro⁃cess and interpret gravity and magnetic data of Xiangshan uranium orefield in Jiangxi,the location and scale of three types of gravity and magnetic rocks at the same source are accurately reflected,including porphyroclastic lava,rhyodacite,and granite porphyry.Additionally,the main rock types of ancient volcanic eruptions are reflected and an ancient volcanic crater with porphyroclastic lava is inferred on basis of the strong negative and positive correlation characteristics of large⁃scale distribution.The uranium orefields in Xiangshan area are mainly distributed in the transition zone between a strong positive correlation and a strong negative correlation,which further reveals the close relationship between the distribution of uranium orefields and the contact surface of lithology.The results can provide a data basis for exploring deep uranium orefields in Xiangshan.
作者
王彦国
田野
邓居智
葛坤朋
WANG Yanguo;TIAN Ye;DENG Juzhi;GE Kunpeng(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,Jiangxi 330013,China;School of Geophysics and Measurement-Control Technology,East China University of Technology,Nanchang,Jiangxi 330013,China)
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2023年第5期1231-1243,共13页
Oil Geophysical Prospecting
基金
国家自然科学基金项目“江西相山火山盆地及邻区穿地壳三维结构及其铀成矿动力学意义”(42130811)
江西省自然科学基金项目“基于方向tilt梯度张量的三维磁异常解释方法研究”(20212BAB203005)联合资助。
关键词
重力二阶垂向导数
归一化磁源强度
互相关系数
噪声扰动
相山铀矿田
second⁃order vertical derivative of gravity anomaly
normalized source strength
cross⁃correlation coeffi⁃cient
noise disturbance
Xiangshan uranium orefield
