Study of Rift-Induced Diamond Diatremes in NW Syria

含金刚石金伯利岩与稳定的太古宙克拉通密切相关，而含金刚石橄榄煌斑岩则侵入邻近的活动带。然而，叙利亚西北部新发现的钻石田与这两种情况不同。叙利亚地堑西部地块侏罗系白云岩中出现的含金刚石裂谷喷发群的年代为110-115万年，与非洲南部、西部和东部、巴西、北美和西伯利亚的中生代反冲事件的年代相似。叙利亚的金刚石寄主岩既不是金伯利岩，也不是煌斑岩，但有些接近于铁长石或玄武岩的成分。未风化的岩心样品是带有蛇纹石、玻璃和矿物碎片的奇特多晶火山碎屑角砾岩，它们镶嵌在碳酸盐基质中。上地幔衍生的捕虏体为石榴石—辉橄榄岩、白云岩和钛铁矿、透辉石和石榴石的离散巨晶。地壳包体为石榴石麻粒岩、辉长岩和角闪岩。北-南叙利亚地堑是东非、埃塞俄比亚、阿法尔、红海和死海裂谷系统的延伸，其中部分裂谷系统至少自侏罗纪以来一直处于活跃状态。在叙利亚西北部的阿拉伯板块中，对已有导管中的古金伯利岩或煌斑岩进行裂陷碱岩浆岩取样，可能是形成非传统金刚石寄主岩的一种模式。这种不寻常的构造环境和混合钻石宿主岩石的奇异性质是本提案的重点。将应用大宗和矿物化学以及稳定同位素技术来测试杂交模型，或者确定这些确实是金刚石稳定场内的初级上地幔熔融产物。

Diamondiferous kimberlites are closely associated with stable Archean cratons, whereas diamond=bearing olivine lamproites are intruded into adjacent mobile belts. However, a newly discovered diamond field in NW Syria differs from both these settings. Clusters of rift-induced diamond-bearing eruptives into Jurassic dolomites of the western block of the Syria Graben are dated at 110-115 m.y., similar in age to the Mesozoic reuptive event in southern, west and east Africa, brazil, North America, and Siberia. Diamond host rocks in syria are neither kimberlites nor lamproites, but some approach the composition of essexite or basanite. Samples of unweathered drill cores are exotic polymict volcanoclastic breccias with serpeintine, glass and mineral fragments set in a carbonate matrix. Upper mantle-derived xenoliths are garnet lherzolite, dunite and discrete megacrysts of ilmenite, diopside, and garnet. Crustal xenoliths are garnet granulites, gabbros, and amphibolites. The N-S Syria Graben is an extension of the East African, Ethiopian, Afar, Red Sea and Dead Sea Rift systems, parts of which have been continuously active since at least the Jurassic. Rift-induced alkali magmatic sampling of paleo-kimberlites or lamproites in pre-existing conduits is one possible model for the generation of the non-trrditional diamond host rocks in the Arabian Plate of NW Syria. This unusual tectonic setting and the exotic nature of the hybrid diamond host rocks is the focus of this proposal. Bulk and mineral chemical and stable isotope techniques will be applied to test the hybridization model, or alternatively to establish that these are indeed primary upper mantle melt products from within the diamond stability field.