当前位置: X-MOL 学术Chem. Geol. › 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.)
The carbon budget of crustal reworking during continental collision: Clues from nanorocks and fluid inclusions
Chemical Geology ( IF 3.9 ) Pub Date : 2022-07-23 , DOI: 10.1016/j.chemgeo.2022.121025
Gautier Nicoli , Alessia Borghini , Silvio Ferrero

The source of volatiles in the continental crust is a long-standing issue. In addition to controlling the amount of melt generated during anatexis, H2O and CO2 budgets of the middle and lower siliciclastic crust are also of great importance for carbonate precipitation, ore concentration, orogenic degassing and carbon storage. Here we focus on two case studies of partially melted metamorphic rocks of crustal affinity– the Ivrea Zone in the Western Alps (0.8 GPa) and the Central Maine Terrane (1.8 GPa), USA. These terrains contain fluid inclusions and carbon-bearing nanogranitoids (former melt inclusions) from which the H2O and CO2 content has been estimated via in-situ analyses. Thermodynamic modelling is used to quantify the amount of internally derived, mineral-bound bulk rock CO2 necessary to reproduce the volatile contents of these melt inclusions. The minimum amount of bulk rock CO2 present at peak metamorphic conditions is estimated at 400 ppm for the Ivrea Zone and 3000 ppm for the Central Maine Terrane. This suggests that the flux of carbon associated with the burial of siliciclastic sediments in the lower crust during the Phanerozoic is 0.2–4.4 Mt. C/yr. These values, as well as the nature of the source of the deep crustal carbon might have changed with time, with periods dominated by internal reworking rather than external inputs. The protracted growth and differentiation of the continental crust through the reworking of supracrustal materials in continental collision settings is a key element of carbon storage processes. The stability of the continental crust through time provides an ultimate, long-lasting reservoir of carbon.



中文翻译:

大陆碰撞过程中地壳改造的碳预算:来自纳米岩石和流体包裹体的线索

大陆地壳挥发物的来源是一个长期存在的问题。除了控制深熔过程中产生的熔体量外,中、下硅质碎屑壳的H 2 O 和CO 2收支对碳酸盐的沉淀、矿石富集、造山脱气和碳储存也具有重要意义。在这里,我们关注两个与地壳亲合的部分熔融变质岩的案例研究——西阿尔卑斯山的伊夫雷亚带(0.8 GPa)和美国缅因州中部地块(1.8 GPa)。这些地形包含流体包裹体和含碳纳米花岗岩(以前的熔体包裹体),其中 H 2 O 和 CO 2含量已通过现场分析估算。热力学模型用于量化重现这些熔体包裹体的挥发性成分所需的内部衍生的、矿物结合的块状岩石 CO 2的量。散装岩石CO 2的最小量据估计,伊夫雷亚区的峰值变质条件为 400 ppm,缅因州中部地块为 3000 ppm。这表明显生宙与下地壳硅质碎屑沉积物埋藏相关的碳通量为 0.2-4.4 Mt. C/yr。这些值以及深部地壳碳源的性质可能随时间而变化,其时期主要是内部改造而不是外部输入。通过大陆碰撞环境中地壳物质的再加工,大陆地壳的长期生长和分化是碳储存过程的关键要素。随着时间的推移,大陆地壳的稳定性提供了一个最终的、持久的碳储库。

更新日期:2022-07-23
down
wechat
bug