【作者】 徐向珍；

【导师】 赵磊；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2006， 硕士

【摘要】 本文是赵磊教授承担的由肖序常院士负责的国家地质调查局“西昆仑构造演化与矿产”项目中的矿产部分。工作区为地质研究程度很低的塔里木地台和田西北部。据资料统计,新疆和田地区从1945年到1996年已发现八颗金刚石,但经多次金刚石找矿工作,仅获一粒尚有争议的镁铝榴石(后经测定为铁铝榴石)。本论文主要从矿物学角度,进行判别、论证,并联系大地构造、航磁物探等情况,从而达到评价金刚石成矿地质条件,指明金刚石找矿方向之目的。 运用现代的先进仪器电子探针EPMA-1000,对石榴石、铬尖晶石类、辉石、橄榄石、钛铁矿等水系重砂矿物进行了详细研究,从整体的指示矿物组合来看,研究区缺乏镁铝榴石、镁钛矿,而铬尖晶石类矿物相对丰富,这是钾镁煌斑岩指示矿物所特有的特点。另外,通过对重砂指示矿物的分析,确定以榴辉岩型的地幔捕虏体为主,橄榄岩型地幔捕虏体为辅。结合以上两点,说明金刚石寄主岩可能是钾镁煌斑岩。 利用辉石地质温压计,反演了本区地幔热状态,工作区地幔温度过高,压力过低,可能不利于金刚石的形成。 综合考虑研究区航磁异常情况与地质构造演化。金刚石产于第三纪河流沉积阶地内,其原生矿应生成于第三纪之前,当时地势北高南低,河流走向由北向南;而铁克里克断隆抬升和河流反向,是在晚第三纪或其后发生的。所以,金刚石原生矿应位于金刚石出土点的北部地区。 最后,本文对金刚石成矿地质条件作出评价,指明金刚石找矿方向。更多还原

【Abstract】 This paper is part of the National Geological Survey Project "The evolution of the western Kunlun and minerals", which is held by Zhao Lei. The degree on geological research is very low in northwest Hetian Area of Tarim Platform. According to the relevant records, 8 diamonds had been found from 1945 to 1966 in Hetian area of Xinjiang;but only one disputable pyrope had been found through repeatedly diamond prospecting. In this paper, basing on the exhaustive study of the natural heavy minerals, taking the conditions of geotectonic evolution and aeromagnetic survey into account, the author tries to assess the diamond geological conditions and points out the way of diamond prospecting.Through electron microprobe analytical technique, garnets, chromites, pyroxenes, ilmenites and olivines are qualitatively and quantitatively studied in this paper. According to the index mineral assemblage, this area lacks of pyrope and geikielitem, while chromspinellide is very rich: which is the distinctive feature of lamproite. In addition, the eclogitic xenolith predominates the mantle xenoliths, and the peridotitic xenolith is secondary. So the native rock of diamond in this area may be lamproite.The mantle thermal state of studied area is calculated through geothermometers and geobarometers. The mantle temperature is high, but the pressure is too low to form diamonds.The aeromagnetic anomaly and the geotectonic evolution are also taken into account. Diamonds are found in Tertiary stream deposit terraces, so the original diamond ores should be formed before Tertiary period when north area was higher than south area and the rivers ran from north to south. It was in late-Tertiary or after this period that Tiekelike block was uplift and the rivers flow direction was reversed. So, primary diamond deposit should be in the north of the locations where diamonds have been found.Finally, this paper makes an assessment on mineralization geological conditions of diamonds and points out the way of diamond prospecting.更多还原