当前位置: X-MOL 学术Geochim. Cosmochim. Acta › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Partitioning of chalcophile and highly siderophile elements (HSEs) between sulfide and carbonated melts – Implications for HSE systematics of kimberlites, carbonatites, and melt metasomatized mantle domains
Geochimica et Cosmochimica Acta ( IF 4.5 ) Pub Date : 2021-05-12 , DOI: 10.1016/j.gca.2021.05.006
Proteek Chowdhury , Rajdeep Dasgupta , Patrick R. Phelps , Cin-Ty A. Lee , Ryan A. Anselm

Highly Siderophile Elements (HSEs; Os, Ru, Ir, Rh, Pt, Pd, Au and Re) combined with their isotopic systematics (Re-Os and Pt-Os) are powerful tools for tracking evolution and genesis of mantle derived magmas. Given sulfides (accessory sulfide minerals and/or molten sulfides) are the primary hosts of HSEs in the mantle and low-degree carbonated melts are extracted from large portions of mantle volume, partitioning of HSEs between sulfide and carbonated melt might play a critical role in distributing HSEs between the mantle and crustal reservoirs. Although, partitioning of HSEs and chalcophile elements between sulfide melt and silicate melt has been previously studied, partitioning of these elements between sulfide melt and carbonated melts has not received much attention. Here we use high P-T experiments to determine the partitioning of HSEs and chalcophile elements (Ni, Co, Mo, Os, Ru, Pd, Pt and Re) between (i) sulfide melt and carbonated silicate melt (CO2 ~ 17 wt.%) and (ii) sulfide melt and carbonatitic melt (CO2 ~ >30 wt.%) at a pressure (P) of 3 GPa and temperatures (T) of 1300–1600 °C in graphite capsules. All experiments produced quenched Fe-sulfide melt blobs + carbonated silicate melt matrix. Concentrations of major elements were measured using electron microprobe, and HSEs and chalcophile elements were measured using LA-ICP-MS. We find that all the elements measured are compatible in the sulfide melt to varying degrees and their Dsulfide/carb. melt sequence is Mo < Co < Ni < Re < Pt ≤ Pd < Ru ≤ Os varying from around 10 for Mo to 105 for Os. Comparing the Dsulfide-carb. melt with Dsulfide-silicate from previous studies, we show that the partition coefficients of HSEs between sulfide and carbonated melts are lower than the partition coefficients of these elements between sulfide and silicate melts, indicating greater mobilization of these elements in carbonatites and carbonated silicate melts. Calculating bulk D (D¯) for carbonated peridotite using our experimentally measured D values, we model the HSE contents of mantle derived low-degree partial melts using an aggregate fractional melting equation and compare the primitive mantle normalized HSE patterns of our model with natural kimberlites, carbonatites, ocean island basalts, and alkaline basalts. We also calculate proportions of sub-lithospheric continental mantle (SCLM) xenolith detritus in the natural kimberlite and carbonatite samples from Karelian, Kaapvaal, Canadian shield and North China craton by using mass balance calculations based on Ru concentration in the primary carbonated melt and the SCLM xenoliths. Our calculations show that detritus proportion in natural kimberlites are 2–28% for Karelian, 7–28% for Kaapvaal, and 6–16% for Canadian shield, which are in agreement with previous studies using various other proxies. We also show that the extent of Re/Os fractionation is less for events of carbonate melt metasomatism as compared to similar events of basaltic melt metasomatism.



中文翻译:

硫化物和碳酸盐熔体之间的硫属元素和高度亲铁性元素(HSE)的划分–对金伯利岩,碳酸盐岩和熔融交代地幔区域的HSE系统学的启示

高度嗜铁元素(HSE; Os,Ru,Ir,Rh,Pt,Pd,Au和Re)及其同位素系统(Re-Os和Pt-Os)相结合,是追踪地幔衍生岩浆演化和成因的有力工具。鉴于硫化物(辅助硫化物矿物和/或熔融硫化物)是地幔中HSE的主要主体,低度碳酸盐熔体是从很大一部分地幔中提取的,因此HSE在硫化物和碳酸盐熔体之间的分配可能起关键作用。在地幔和地壳储层之间分布HSE。尽管以前已经研究了HSE和亲硫元素在硫化物熔体和硅酸盐熔体之间的分配,但是这些元素在硫化物熔体和碳酸盐熔体之间的分配并未引起太多关注。在这里我们使用高PT实验,以确定HSE元件之间亲硫元素(镍,钴,钼,锇,钌,钯,铂和R e)的分割(ⅰ)硫化物熔化和碳酸硅酸盐熔体(CO 2  〜17%(重量))和(ii)硫化物熔化并carbonatitic熔体(CO 2 在压力(〜> 30重量%)P为3GPa和温度(的)Ť的1300-1600℃)石墨胶囊。所有实验均产生了淬火的Fe-硫化物熔体团块+碳酸化的硅酸盐熔体基质。使用电子探针测量主要元素的浓度,并使用LA-ICP-MS测量HSE和亲硫元素。我们发现,所测量的所有元素在硫化物熔体及其D硫化物/碳水化合物中都相容。熔化顺序为Mo <Co <Ni <Re <Pt≤Pd <Ru≤Os,从Mo的大约10到Os的10 5。比较D硫化物-碳水化合物。熔体d硫化物硅酸盐从先前的研究中,我们表明,硫化物和碳酸熔体之间HSE元件的分配系数比硫化物和硅酸盐熔体之间的这些元素的分配系数降低,这表明在碳酸这些元件的更大的动员和碳酸硅酸盐熔体。计算批量D(d¯),使用我们的实验测得的D值,我们使用总分数熔融方程对地幔衍生的低度局部熔体的HSE含量进行建模,并将我们模型的原始地幔归一化HSE模式与天然金伯利岩,碳酸盐岩,大洋洲玄武岩和碱性玄武岩进行比较。我们还使用基于原始碳酸盐熔体和SCLM中Ru浓度的质量平衡计算方法,计算了来自Karelian,Kaapvaal,加拿大盾构和华北克拉通的天然金伯利岩和碳酸盐岩样品中的岩石圈以下大陆幔(SCLM)异岩碎屑的比例。异石。我们的计算表明,天然金伯利岩中碎屑的比例对于卡累利阿人来说是2–28%,对于Kaapvaal是7–28%,对于加拿大盾来说是6–16%,这与以前使用其他代理的研究一致。

更新日期:2021-05-26
down
wechat
bug