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阿拉伯-努比亚地盾中长石、全岩及方铅矿样品中普通铅的新老数据可以分成两大组:Ⅰ组铅,具有大洋(地幔)特征;Ⅱ组铅,混入了早于元古界的大陆地壳成分。前者见于埃及的红海丘陵及阿拉伯地盾的西部与南部。后者见于地盾的东北部与东部,以及邻近Najran的东南部,此外,在南边的也门,东边的阿曼。西边的埃及阿斯旺也有所见。普通铅数据的这种分布特点表明,阿——努地盾具有一个大洋性的陆核,其外围的岩石则至少有一部分是由较古老的大陆物质所形成。较古老的铅混入元古代岩石中的机制可能有两种:1.直接来自下伏早于元古代的基底;2.通过远海沉积物或来自附近大陆的沉积物的俯冲。这两种机制在地盾的不同地区起的作用不同。新的锆石的铀一铅年龄数据表明,在阿拉伯地盾东部的Jabal Dahul东南有早元古代基底的存在。在Al Amar断层带中还发现了年龄达20亿年的锆石,所有这些资料证实了普通铅数据的推测,即东部阿拉伯地盾至少有一部分具有更古老的大陆基底。因为大陆边缘特别有利于成矿,所以,上述发现可能对找矿有重要的指导意义,特别是对于锡、钨、钼等矿床的勘查。
The new and old data on common lead in the mid-feldspar, whole rock and galena samples from the Arabian-Nubian shield can be divided into two groups: Group I, with oceanic (mantle) characteristics; Group II, Proterozoic continental crust composition. The former is found in Egypt’s Red Sea hills and the Arab shield in the west and south. The latter is found in the northeast and east of the shield and in the southeast of neighboring Najran, in addition to Yemen in the south and Oman in the east. Aswan in the west of Egypt also see. This distribution of common lead data suggests that the Ah-Nudi shield has an oceanic core that is at least partially surrounded by older continental material. There are two possible mechanisms for the incorporation of older lead into Proterozoic rocks: 1. Directly from the basement underlying the Proterozoic; 2. Subduction through distant sea sediments or sediments from the nearby continent. These two mechanisms play different roles in different parts of the Earth Shield. The new uranium-lead age data for zircon indicate that there are pre-Proterozoic basement southeast of Jabal Dahul in the eastern part of the Arabian Shield. Also found in the Al-Amar fault belt are zircons dating to 2 billion years old, all of which confirm the general lead data that at least part of the eastern Arabian shield has an older continental base. Because the continental margin is particularly favorable for metallogenesis, the above findings may have important guiding significance for prospecting, especially for the exploration of tin, tungsten and molybdenum deposits.