辽宁瓦房店50号金伯利岩管深部找矿新进展及成矿模型研究

    Deep exploration of No.50 kimberlite pipe in Wafangdian, Liaoning Province: New advances and metallogenic model

    • 摘要: 50号金伯利岩管是国内极为重要的金刚石矿体,也是辽宁唯一开发利用的大型原生金刚石矿体,因其品位高、品质好而享誉国内外.近年在构造控形认识指导下,于50号岩管周边采用三维构造填图技术、井中物探方法组合、浅层地震技术、钻探工程等手段,开展寻找50号岩管深部隐伏矿体工作,成功在远离50号岩管1 000 m之外、埋藏深度近300 m的地方发现了50-1号金伯利岩管.经过比对认为与50号岩管特征一致,推测是50号岩管被错断的一个断块.根据50号岩管深部找矿最新发现,将其构造背景与岩相学特征相结合,从而建立50号岩管成矿模型.在华北克拉通岩石圈地幔,金伯利岩浆侵入地幔橄榄岩,金刚石伴随着地幔橄榄岩进入金伯利岩浆并促使岩浆迅速上升.岩浆上升至近地表处喷发,伴随气体溶出和膨胀,岩浆迅速冷却固结形成50号金伯利岩管.后期受到推覆构造运动影响,50号金伯利岩管下部发生错断位移,一部分为新发现的50-1号金伯利岩管,而剩余的根部相主体则还未被发现.

       

      Abstract: The No. 50 kimberlite pipe, a diamond orebody of critical importance in China, is the only large-scale primary diamond deposit being exploited in Liaoning Province. It is renowned both domestically and internationally for its high grade and superior quality. Guided by recent insights into structural controls, an exploration project was implemented around No. 50 pipe for hidden ore bodies, utilizing a suite of advanced techniques, including 3D structural mapping, shallow seismic profiling, drilling, and a combination of borehole geophysical methods. This effort successfully led to the discovery of No. 50-1 kimberlite pipe, located approximately 1 000 meters beyond the original No. 50 pipe at a burial depth nearly 300 meters. Comparative analysis confirms that its characteristics are consistent with those of No. 50 pipe, supporting the interpretation that it is a structurally displaced block severed from the major pipe. Building upon this new discovery from the deep-seated exploration, the paper proposes a metallogenic model that integrates its tectonic setting and petrological characteristics. The model posits that within the lithospheric mantle of North China Craton, kimberlitic magmas intruded mantle peridotite. Diamonds, hosted within this mantle peridotite, were incorporated into the kimberlitic magma, facilitating its rapid ascent. Upon reaching sub-surface levels, explosive degassing and volatile expansion triggered rapid cooling and solidification, forming No. 50 pipe. Subsequently, thrust faulting dismembered the original pipe system, displacing a segment now identified as No. 50-1 pipe, while the primary root zone of No. 50 pipe remains undiscovered.

       

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