广东大亚湾西北部新发现铀矿点及找矿远景讨论

New discovery of uranium ore spot and prospecting discussion in north western Dayawan,Guangdong province.

2003年在广东大亚湾西北部新发现了一处火山岩型铀矿点,经刻槽取样分析,铀矿石品位高达0.459%。该处铀矿物成份主要是沥青铀矿和次生铀矿物,前者 UO_2最高为94%,Al_2O_3<1%,P_2O_5含量变化大,按照 P_2O_5含量可分两组,其一变化于2.23%～2.57%,另一组变化于17.96%～19.95%;次生铀矿物含 UO_3大约为60%左右,Al_2O_3在1.6%～3.0%之间,P_2O_5变化于10%～15%。对含矿岩石及围岩进行了岩石学和地球化学研究,结果表明,出露的岩石主要为流纹质岩石,与著名的相山矿田的岩石类型相似。岩石具有高的 LREE/HREE 值,Eu 负异常并不普遍。从主、微量元素及稀土元素特征来看,含矿岩石及围岩差别不大,总特征与一般的钙碱性火山岩相似。新发现的铀矿化带范围虽然不大,但含矿岩石铀品位高,所处构造环境与相山铀矿田的某些矿床有一定的相似性,是值得注意和进一步工作的地区。

A volcanic rock-type uranium ore-spot was discovered with airborne gama-ray spectrometry in north-western Dayawan , Guangdong Province in 2003. The ore grade of mineralization zone is up to 0. 459% in ditch sampling analyses. Uranium minerals of the ores are uraninite and altering uranium minerals. The Uraninite has high UO2 （ maximum about 94% ） , low Al2O3 （ 〈 1% ） and variable P2O5 contents. Two groups can be subdivided according to P2O5 contents, one ranges between 2. 23% and 2. 57% , another between 17.96% and 19.95%. The altering uranium minerals contain UO3 about 60% , 1.6% to 3.0% in Al2O3 and 10% to 15% in P2O5. Ores-host rocks for ore spot have the characteristics as follows, they are mainly rhyolites and in the TAS diagram, similar to those in ＂Xiangshan Uranium Ore Field＂. Whole rocks composition between ores and wall rocks in this area does not show great distinction. The ores and wall rocks in ore spot have similar REE and traces elements, essentially the characteristics of geochemistry similar to those of calc-alkaline volcanic rocks. They have higher LREE/HREE ratios and slightly negative Eu anomalies. Although the scale of the uranium mineralization zone is not larger enough, the content of uranium ores is higher. Moreover, the tectonic background is similar to some deposits in＂ Xiangshan Uranium Ore Field＂. Thus, the discovery of uranium prospective area is significant for further exploration and research.