当前位置: X-MOL 学术Miner. Deposita › 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.)
Petrogenesis of extra-large flake graphite at the Bissett Creek deposit, Canada
Mineralium Deposita ( IF 4.8 ) Pub Date : 2022-12-05 , DOI: 10.1007/s00126-022-01145-9
Cameron Drever 1 , Carson Kinney 1 , Chris Yakymchuk 1
Affiliation  

The petrogenesis of extra-large flake graphite is enigmatic. The Bissett Creek graphite deposit, consisting of flake graphite hosted in upper-amphibolite facies quartzofeldspathic gneisses and rare aluminous gneisses, provides an analogue for graphite exploration. In the Bissett Creek gneisses, graphite is homogeneously distributed and composes 2–10 vol. % of the rocks. Disseminated graphite flakes (~ 1 to 6 mm in size) are interleaved with biotite and are petrologically associated with upper-amphibolite facies metamorphic mineral assemblages. Thermobarometry and phase equilibrium modeling yield peak temperatures of > 760 °C at 0.5–0.9 GPa. Whole-rock samples with abundant graphite yield δ13CVPDB from − 28 to − 14‰. δ34SVCDT values of sulfide-bearing samples vary from 10 to 15‰. Sulfur and carbon isotope values are compatible with a biogenic origin, flake graphite probably formed from metamorphism of in situ organic material. However, the variability of δ13C values from the deposit along with graphite microstructures suggest that carbon-bearing metamorphic fluid (or melt) generated during metamorphism may have remobilized carbon resulting in anomalously large to extra-large flake sizes. This may be a common mechanism globally to explain large graphite flake sizes where graphite formed through in situ metamorphism of organic matter is coarsened due to remobilization of CO2-rich fluids (or melt) during high-temperature metamorphism.



中文翻译:

加拿大 Bissett Creek 矿床超大片状石墨的岩石成因

超大片状石墨的成因是个谜。Bissett Creek 石墨矿床由上部角闪岩相石英长石片麻岩和稀有的含铝片麻岩中的片状石墨组成,为石墨勘探提供了类似物。在 Bissett Creek 片麻岩中,石墨均匀分布并组成 2-10 体积。% 的岩石。分散的石墨片(大小约 1 至 6 毫米)与黑云母交错,在岩石学上与上部角闪岩相变质矿物组合有关。在 0.5–0.9 GPa 时,热压法和相平衡模型产生的峰值温度 > 760 °C。富含石墨的全岩样品产生 δ 13 C VPDB从 − 28 到 − 14‰。δ 34 S VCDT含硫化物样品的值从 10 到 15‰不等。硫和碳同位素值与生物来源相容,片状石墨可能由原位有机材料的变质作用形成。然而,沉积物中δ 13 C 值的可变性以及石墨微观结构表明变质过程中产生的含碳变质流体(或熔体)可能使碳重新流动,从而导致异常大到超大的薄片尺寸。这可能是全球通用的解释大石墨片尺寸的机制,其中通过有机物原位变质形成的石墨由于高温变质过程中富含 CO 2 的流体(或熔体)的再流动而变粗。

更新日期:2022-12-06
down
wechat
bug