• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Lithos: An International Journal of Mineralogy, Petrology, and Geochemistry >Sulphide survival and diamond genesis during formation and evolution of Archaean subcontinental lithosphere: A comparison between the Slave and Kaapvaal cratons
【24h】

Sulphide survival and diamond genesis during formation and evolution of Archaean subcontinental lithosphere: A comparison between the Slave and Kaapvaal cratons

机译：古生界次大陆岩石圈形成和演化过程中的硫化物存活和钻石成因：奴隶和Kaapvaal克拉通之间的比较

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Sulphide inclusions from 35 edogitic and 7 peridotitic diamonds from the Diavik kimberlites in the central Slave craton have been characterized to address questions of diamond age and craton formation. Eclogitic sulphide inclusions occur in diamonds with mantle-like δ~(13) (- 4.94 ± 0.72 1σ) and low N aggregation states (%N as B = 8.2 ±10.0, average N contents of 720 ppm) indicative of relatively low mantle residence temperatures. A 1.86 ± 0.19 Ga Re-Os age array for edogitic sulphides with suprachondritic initial ~(187)Os/~(188)Os of 0.13 (±0.10) indicates a close temporal link between edogitic diamond formation, edogite emplacement and collisional events affecting the Slave craton. Sulphides in peridotitic diamonds plot on older, previously established 3.3 and 3.5 Ga isochrons, consistent with higher average N aggregation states (-20%) despite lower N contents (～230 ppm) for their host diamonds compared to edogitic diamonds. Two intriguing observations emerge from a comparison of diamond populations and formation ages between the Slave and Kaapvaal that indicate fundamentally different and common diamond formation mechanisms, respectively: (1) Despite the general abundance of peridotitic silicate inclusions, peridotitic sulphide inclusions are rare in the Kaapvaal and occur in relatively young diamonds whereas in the central Slave there is a sizable Archaean population. (2) Compared to the distribution of silicate inclusions in diamonds, both cratons have an overabundance of edogitic relative to peridotitic sulphide inclusions. During Kaapvaal lithospheric mantle formation, large melting intervals, as gauged by extremely depleted silicate inclusions in diamonds, led to exhaustion of sulphide in the residue. Formation of peridotitic sulphide inclusion-bearing diamonds occurred only significantly later, after re-sulphidation accompanying metasomatism. By contrast, the less depleted deep lithospheric mantle beneath the central Slave craton may have formed during plume subcretion, leading to smaller melting intervals due to the presence of a pre-existing lithospheric mantle lid, thereby allowing for coeval precipitation of sulphide inclusion-bearing diamonds. Abundant edogitic sulphide inclusion-bearing diamonds that can be related to accretionary processes along the edges of the Slave and Kaapvaal craton indicate that sulphide-saturated eclogite is a fertile source for diamond formation. Reduced fluids from dehydration of underlying seawater-altered peridotite may react with the overlying oceanic crust to precipitate edogitic sulphide-bearing diamonds penecontemporaneously with metamorphism and tedonic emplacement of eclogite into the subcratonic lithosphere.
机译：来自奴隶克拉通中部Diavik金伯利岩的35颗辉度钻石和7个橄榄岩钻石的硫化物夹杂物已被表征，可以解决钻石年龄和克拉通形成的问题。闪长岩硫化物夹杂物存在于具有类似地幔的δ〜（13）（-4.94±0.721σ）和低N聚集态（％N，B = 8.2±10.0，平均N含量为720 ppm）的钻石中，表明地幔的残留量相对较低。温度。上颌晶状体初始〜（187）Os /〜（188）Os为0.13（±0.10）的嗜酸性硫化物的1.86±0.19 Ga Re-Os年龄阵列表明，嗜酸性金刚石的形成，钙铁矿的位置和碰撞事件之间的紧密时间联系奴隶克拉通。橄榄岩钻石中的硫化物分布在较早的，先前建立的3.3和3.5 Ga等时线上，与母体钻石的N含量（〜230 ppm）相比，较低的平均N聚集态（-20％）相一致，而edogitic钻石却是如此。从奴隶和Kaapvaal的钻石种群和形成年龄的比较中得出两个有趣的发现，分别表明根本不同和常见的钻石形成机制：（1）尽管橄榄石硅酸盐包裹体普遍丰富，但在Kaapvaal中很少有橄榄石硫化物包裹体并以相对较年轻的钻石出现，而在奴隶中心则有相当数量的古生族。 （2）与钻石中硅酸盐包裹体的分布相比，两个克拉通相对于橄榄石化硫化物包裹体都具有过量的edogitic。在Kaapvaal岩石圈地幔的形成过程中，大的熔融间隔（由钻石中硅酸盐夹杂物的严重耗尽所确定）导致残留物中的硫化物耗尽。伴随着交代作用的再硫化后，含橄榄石的含硫化物包裹体钻石的形成仅在显着的后期才发生。相比之下，在羽状泥浆沉积过程中，从奴隶克拉通下方的岩石层消耗较少的深层地幔可能已经形成，由于存在岩石圈地幔覆盖层而导致较小的熔融间隔，从而使含硫化物夹杂物的钻石同时沉淀。 。可能与沿奴隶和Kaapvaal克拉通边缘的增生过程有关的大量含edogitic硫化物的含钻石，表明硫化物饱和榴辉岩是形成钻石的沃土。下层海水蚀变的橄榄岩脱水后产生的减少的流体可能会与上覆的洋壳发生反应，从而使含硫化碳的含钻石的变质作用和白垩纪的榴辉岩入渗进入下克拉通岩石圈。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号