安徽宿州栏杆地区金刚石成矿地质条件及成因

Metallogenic Geological Condition and Metallogenesis of Primary Dimaond Deposit in Langan District in Suzhou City,Anhui Province

安徽省宿州市栏杆地区位于华北地台东南缘,近年来在基性岩中发现了原生金刚石,圈定了2个强风化残积型金刚石矿体,辉绿岩为金刚石的主要载体,是我国首次在基性岩中发现原生金刚石,取得了找矿重大突破,经储量评审,已达小型规模。根据栏杆地区的找矿成果,对金刚石矿床地质特征、金刚石形成的地质条件及成因展开了研究。结果表明:(1)该区原生金刚石矿为一种新的成因类型,主要与老寨山辉绿岩岩体有关,与传统认为的超基性的金伯利岩与钾镁煌斑岩为金刚石矿的成矿母岩不同,基性岩为金刚石矿的主要载体;(2)金刚石矿形成的地质条件主要有华北地台长期稳定的克拉通、平缓的沉积盖层、发育有深大断裂及次级断裂的系统、老寨山辉绿岩岩体、大量指示矿物、风化残积作用等;(3)栏杆地区原生金刚石矿的成因可能为捕获成因,即在原生金刚石形成后,被深部近软流圈地幔中已经形成的基性岩浆在上升的过程中捕获,通过郯庐断裂带及其次级断裂带以较快的速度携带至地表,是多阶段、多期次发展的产物。

Langan District in Suzhou City of Anhui Province locates at the southeast part in north China, primaU diamond is found in the basic rock in recent years, two strongly weathered residual type di- amond orebodies are delineated, and diabase is the main carrier of diamond, this is the first time in China for finding primary diamond in the basic rock, great breakthrough has been gained, after mineral reserves review, the small scale can be reached. According to the prospecting achievements of Langan District,the geological characteristics of diamond deposit,the geological conditons and genesis of the diamond deposit are studied. The results show that ：①genesis of the primary diamond deposit is a new genetic type which mainly have relationship with diabase rock mass in Laozhai Mountain, this is not same as the traditional concept that the ultrabasic kimberlite and potassium-magnesium lamprophyre are different fronl the ore- forming parent rocks of diamond deposit,basic rock is the main carrier of diamond deposit ;②the relevant geological conditions of diamond mineralization are mainly for long term stable archean craton in North China Platform, gentle sedimentary cover, development of deep major dislocation and secondary dislocation system, diabase rock mass in the Laozhai Mountain,large number of indicative minerals, effect of weathe-ring and residue etc. ;③metallogenic genesis of the original diamond deposit in Langan Distric may be capture causes,which can be discribed that after the formation of primary diamond, it is captured in the rising process of basic magma formed in the deep mantle near asthenosphere, and it is quickly carried to the surface through Tanlu fracture zone and its secondary fault zone,the diamond deposit in Langan Dis- trict is the outcome of multi-stage and multi-period development.