鞍本古陆块图像识别方法研究

发布时间：2018-10-21 09:23

【摘要】：古陆块不仅可以用来指示地壳演化历史,而且与铀多金属成矿关系密切,识别古陆块的研究具有重要的理论和实际意义。目前对古陆块特征及识别方法的研究仍限于从地质角度展开,例如岩石地球化学、同位素年代学等方面,还没有开展地学综合特征和识别技术方法研究。华北陆块是我国最大的古老陆块,其北部边缘包含有许多相对较小的块体。鞍本古陆块是华北陆块地壳演化较早,成熟度较高的地区,3800Ma就有了原始古陆的记录。该地区除发现了我国著名的鞍山式铁矿和有色金属矿床外,还产出了我国最古老的3075铀矿床。本文以鞍本古陆块的辽东地区为例,尝试利用地球物理和遥感等多源信息来刻画古陆块的特征,通过引入分形几何、变差函数等概念,探讨古陆块的遥感—地球物理识别流程和技术方法,为古陆块的识别提供新思路。本文首先通过资料的调研,分析总结古陆块的地质特征,在此基础上先利用地球物理信息研究古老变质岩的磁性特征、中酸性岩浆岩的重力特征和钾质花岗岩的放射性特征;然后利用遥感图像信息研究区分古老变质岩和基性岩体、变质岩与沉积岩、酸性喷出岩与侵入岩以及不同时代岩体的识别技术和方法;最后利用地理信息系统空间分析方法圈定既具有古老深变质岩类,又具有古老钾质花岗岩体分布的区域作为古老地块。本文取得的主要研究成果如下:(1)通过对鞍本地区57种主要岩石的磁化率分析,发现太古界变质岩的磁化率平均值为27871.5×10-6,明显大于下元古界平均值1614.27×10-6,更显著高于其它时代的沉积变质岩,但低于基性火山岩。在此基础上,利用磁异常来识别和圈定太古界变质岩和基性火山岩分布范围。(2)通过区内岩石密度参数分析,发现区内花岗岩类的密度为2.56 g/cm3~2.59g/cm3,处于全部岩石的低值区,并利用重力异常来识别和圈定中酸性侵入岩体范围。(3)钾质花岗岩体的放射性特征明显,与其它地层岩性相比,钾质花岗岩体的钾含量较高,且铀钍比值较低。(4)与区内各地质单元对比发现,酸性岩浆岩(侵入岩和喷出岩)的铀、钍、钾含量较高,因此可以利用航空放射性数据,通过选取合适阈值提取酸性岩浆岩。(5)酸性侵入岩(花岗岩)和喷出岩(流纹岩)遥感图像不仅目视特征不同,多重分形谱也存在差异,侵入岩的多重分形谱比喷出岩具有更好的对称性和更小的多重分形谱展布区间。(6)不同时代花岗岩体由于形成时间、经历活动期次等差异,造成其纹理复杂程度和发育特征不同,时代较老的花岗岩比新花岗岩具有更宽的多重分形谱展布区间。(7)变质岩类由于其遥感图像独有的栉状、梳状水系,明显区别于沉积岩与岩浆岩的目视特征,而且在变差分析中表现为更小的长、短轴变程。(8)根据古陆块的地质含义和本文得到的遥感地球物理特征,初步建立了古陆块的识别流程,并用于鞍本古陆核的识别,同时探讨分析了古陆块与铀成矿的关系。
[Abstract]:The ancient land block not only can be used to indicate the history of crustal evolution, but also closely related to uranium polymetallic mineralization, and it is of great theoretical and practical significance to identify the study of ancient land masses. At present, the research on the characteristics and identification methods of ancient land blocks is still limited to the development of geological angle, such as rock geochemistry, isotope geochemical exploration, etc. North China land block is the largest ancient land block in China, its northern edge contains many relatively small blocks. The ancient land block of saddle is a region with early crustal evolution and higher maturity in North China, and 3800Ma has the record of primitive ancient land. In addition to the discovery of the famous iron ore and non-ferrous metal deposit in our country, this area also produces the oldest 3075 coal mine in our country. In this paper, we attempt to describe the characteristics of ancient land blocks by using multi-source information such as geophysical and remote sensing as an example. By introducing the concepts of fractal geometry, variation function and so on, this paper discusses the process and technique of remote sensing and geophysical recognition of ancient land blocks. and provides a new idea for the identification of the ancient land block. Based on the investigation of data, this paper summarizes the geological characteristics of ancient land blocks, and then uses the geophysical information to study the magnetic characteristics of the old metamorphic rocks, the gravity characteristics of the acidic magmatic rocks and the radioactive characteristics of the potassium granite. Then using the remote sensing image information to study the identification techniques and methods for distinguishing the old metamorphic rock and the basic metamorphic rock, the metamorphic rock and the sedimentary rock, the acidic jet rock and the intrusive rocks as well as the different times rock mass, and finally using the spatial analysis method of the geographical information system to delineate the ancient deep metamorphic rocks. and also has the area of the distribution of the ancient potassium granite body as an ancient parcel. The main results obtained in this paper are as follows: (1) By analyzing the magnetic susceptibility of 57 main rocks in saddle region, it is found that the average magnetic susceptibility of the metamorphic rocks in the Taigu boundary is 27871. 5 Mt. 10-6, which is significantly higher than that of the sedimentary metamorphic rocks of the other times. but lower than that of volcanic rocks. On this basis, magnetic anomalies are used to identify and delineate the distribution range of metamorphic rocks and volcanic rocks in Taigu. (2) Through the analysis of rock density parameters in the region, it is found that the density of granite in the region is 2.56g/ cm3 ~ 2.59g/ cm3, which is in the low value area of all rocks, and uses gravity anomaly to identify and delineate the range of acid intrusive rock mass. (3) The radioactive characteristic of the potassium granite body is obvious, and the potassium content of the potassium granite body is high compared with other formation lithology, and the uranium content ratio is lower. (4) Compared with the geological units in the region, it has been found that the uranium, potassium and potassium contents of acidic magmatic rocks (intrusive rocks and ejected rocks) are high, so that the aviation radioactivity data can be used to extract the acidic magmatic rocks by selecting appropriate thresholds. (5) The remote sensing images of acidic intrusive rocks (granite) and ejected rock (rhyolite) not only have different visual characteristics, but also differ in multiple fractal spectra. The multiple fractal spectra of intrusive rocks have better symmetry and smaller multiple fractal spectrum distribution intervals than those of sprayed rock. (6) In different times, the granite bodies have different texture complexity and development characteristics due to the formation time and the active time, and the older granite has a wider multi-fractal spectrum distribution interval than the new granite. (7) Metamorphic rocks are distinguished from the visual characteristics of sedimentary rocks and magmatic rocks because of their unique topography and comb-like water system. (8) According to the geological meaning of the ancient land block and the remote sensing geophysical characteristics obtained in this paper, the identification process of the ancient land block was preliminarily established, and the relationship between the ancient land block and uranium mineralization was also discussed.
【学位授予单位】：核工业北京地质研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P619.14;P627

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