地球系统科学论坛第451期：陈唯副教授、王超副教授报告会

报告题目：Carbonate Melts and Carbonatites 陈唯 副教授

碳循环与华北克拉通破坏 王超 副教授

报告时间：5月12日（周四）下午3:00

报告地点：主楼412

报告人简介：陈唯，在南京大学取得学士学位，美国University of Notre Dame取得博士学位。目前在中国地质大学地质过程与矿产资源国家重点实验室从事科学研究，主要研究方向是火成碳酸岩和激光剥蚀(MC)-ICP-MS分析方法。其研究成果发表在Nature Communication, Chemical Geology等杂志上。

报告内容简介：Carbonatites are rare igneous rocks formed predominantly of carbonate (>50%). They are derived from the mantle with little crustal contamination based on their Sr-Nd-Pb isotopic data, stable isotopic compositions, noble gases, and experimental phase equilibria. Though considered ‘exotic’ in nature, carbonatite melts have a profound impact on the chemical and physical properties of the mantle due to their unique geochemical nature, and serve as highly efficient transport agents of carbon from the mantle to the crust. However, the exact origin of parental melts to carbonatites remains uncertain; i.e., prevalent models include solely lithosphere-controlled origin, a mixture between lithospheric and asthenospheric components, an asthenopheric, plume-related origin, or even in the deep mantle. The limit to the depth of carbonate melts plays a fundamental control on the mobility and long-term storage of deep carbon in Earth.

王超，男，辽宁大连人。2000C年毕业于吉林大学物理学院，获得学士学位；2006年毕业于吉林大学化学学院，获得博士学位；2007-2010年在中国地质大学（武汉）从事博士后研究工作；2010年进入中国地质大学（武汉）工作，现为副教授。

主要研究领域包括：地球碳循环的高温高压实验研究；高温高压条件下壳幔岩石的部分熔融、熔体-围岩反应和岩浆混合过程研究；高温高压条件下岩石、矿物热传导性质研究；新材料的高温高压合成研究。目前已在JGR、CrystEngComm等杂志发表SCI论文12篇。在研的科研项目有：国家自然科学基金面上项目一项（主持），国家自然科学基金重点项目一项（参与），973项目子课题一项（参与）。

报告内容简介：The Archean cratonic lithosphere is well known as buoyant, refractory and anhydrous, and hence long lived in the earth’s history. However, some of the Precambrian cratons, such as the Wyoming craton and North China Craton (NCC), underwent extensive thinning and modification in the Neoproterozoic and Phanerozoic. NCC has been a type region for the study of craton reactivation and reworking in the world. Despite significant progress in our understanding of NCC destruction, there are still significant controversies with respect to the mechanism of destruction. Several models were proposed to explain the NCC destruction, including thermochemical erosion, delamination, peridotite–melt interaction, lithosphere extension and subduction dehydration. However, all of these models have some pitfalls. For example, the calculated density profile of the upper mantle didn’t support the delamination model (Djomani et al., 2001); the result of numerical simulation suggests that the thickness of lithospheric thermal-mechanical thinning caused by small-scale convectional instability is not more than 30 km due to the low thermal conductivity and viscosity of lithospheric mantle.

Hammouda and Laporte (2000) report the experimental results on carbonatite melts infiltration in polycrystalline olivine at 1.0 GPa and 1300 °C. They demonstrate that carbonatite melts can percolate very quickly along grain boundaries in olivine aggregate to form porridge-like texture. If these results can be extrapolated to higher pressure (e.g. >5.0 GPa) in the system of nature carbonate and harzburgite, then carbonatite melts maybe a potentially powerful media to arise the destruction of craton. We suggested that, at first, the cratonic lithospheric mantle could be greatly softened by carbonatite melts, and afterward gradually thinned by mantle convection. Then, the eclogitic lowermost crust together with the residual lithospheric mantle may found into asthenosphere due to gravity instability.

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2016年5月10日