扎赉诺尔坳陷带砂体特征及找铀矿方向分析

Characteristics of sand bodies in Zalailuoer depression and analysis of uranium exploration direction

扎赉诺尔坳陷带内诸凹陷具有不同的沉积特征和砂体特点,查干诺尔和克鲁伦凹陷砂体形成于粗粒冲积扇和扇三角洲沉积体系,砂体厚度变化大,相变快,有机质含量低,顶底板均不发育;呼伦湖凹陷以小型三角洲平原相砂体为主,具有较稳定的泥砂岩结构,有机质含量高,砂体厚度和横向延伸较稳定,但砂体铀含量较低;胡列也吐凹陷砂体以辫状河三角洲体系产出为主,砂体厚度大,延伸稳定,底板发育,顶板发育不完全,砂体铀含量高。扎赉诺尔坳陷带各凹陷砂体的不同特点,决定了它们具有不同的找矿潜力。通过砂体综合条件对比分析,笔者认为胡列也吐凹陷和克鲁伦凹陷砂体铀成矿条件较好,呼伦湖凹陷次之,查干诺尔凹陷较差。

Each sag in Zalailuoer depression has its own characteristics of sedimentary system and sand bodies. The sand bodies in Chaganluoer sag and Kelulun sag are formed in fan and delta sedimentary system with coarse grain sediments. The thickness of sand bodies varies very much and their facies change very fast, having a low content of organic materials and poorly developed upper and botton mud set. Sand bodies in Hulunhu sag mainly formed in small delta with relatively stable mud-sand-mud structure and high content of organic materials. The sand bodies are stable in thickness and lateral spreading, but sand bodies have low uranium content. Sand bodies in Huleyetu sag mainly formed in braided delta sedimentary system and with a relatively thick sand body. The distribution of sand bodies is stable and the bottom mud set is well developed, but the upper one is poorly developed. Its sand bodies have a high uranium content. Different characteristics of sand bodies of each sag in Zalailuoer depression result in different potential of uranium ore formation. On the basis of comprehensive contrast, the authors arrive the conclusion that Huleyetu sag and Kelulun sag has fairly good condition of uranium metallogency. Hulunhu sag has less good condition and Caganluoer sag are not favorable for uranium formation.