Secular cooling and crystallization of partially molten Archaean continental crust over 1 Ga   总被引：1，自引：1，他引：0  

Olivier Vanderhaeghe  Célia Guergouz  Cécile Fabre  Stéphanie Duchêne  David Baratoux 《Comptes Rendus Geoscience》2019,351(8):562-573

The protracted tectonic and magmatic record of cratons over the Archaean Eon has been classically interpreted in terms of long-lived shallow-dipping subduction or repeated mantle plumes. In this paper, we use the 1D conductive heat equation to model the evolution of the geotherm of a generic felsic-dominated Archaean cratonic nuclei solely considering the secular decay of radioactive isotopes (²³⁸U, ²³⁵U, ²³²Th, and ⁴⁰K), responsible for heat production in the crust. Using a range of plausible parameters for crustal thickness, lithospheric thickness, and surface heat flux, this modelling shows that Archaean crust was characterized by an initially high geothermal gradient at 3.5 Ga, with a Moho temperature close to 900 °C, and that it might have remained partially molten for about one billion years. The existence of a partially molten crust for an extended period of time offers an alternative option to shallow-dipping subduction or repeated mantle plumes for the understanding of the peculiar tectonic evolution of Archaean cratons marked by (i) protracted high-temperature metamorphism and magmatism associated with crustal differentiation, and (ii) widespread deformation characterized by structural domes attributed to the development of crustal-scale gravitational instabilities.  相似文献   

Electrical-hydraulic conductivity model for a weatheredfractured aquifer system of Olbanita,Lower Baringo Basin,Kenya Rift     

Benjamin SOSI  Justus BARONGO  Albert GETABU  Samson MAOBE 《地下水科学与工程》2019,(4):360-372

Groundwater yield in the Kenya Rift is highly unsustainable owing to geological variability.In this study,field hydraulic characterization was performed by using geoelectric approaches.The relations between electrical-hydraulic(eh)conductivities were modeled hypothetically and calibrated empirically.Correlations were based on the stochastic models and field-scale hydraulic parameters were contingent on pore-level parameters.By considering variation in pore-size distributions over eh conduction interval,the relations were scaled-up for use at aquifer-level.Material-level electrical conductivities were determined by using Vertical Electrical Survey and hydraulic conductivities by analyzing aquifer tests of eight boreholes in the Olbanita aquifer located in Kenya rift.VES datasets were inverted by using the computer code IP2Win.The main result is that ln T=0.537(ln Fa)+3.695;the positive gradient indicating eh conduction through pore-surface networks and a proxy of weathered and clayey materials.An inverse(1/F-K)correlation is observed.Hydraulic parameters determined using such approaches may possibly contribute significantly towards sustainable yield management and planning of groundwater resources.  相似文献   

小秦岭地体边缘断裂特征及其演化     

裴锋敏  郭抗衡  胡能高 《河南国土资源》1995,(3)

本文论述了小秦岭地体边缘断裂三个阶段４期活动的构造特征和演化过程。阐明了断裂带在地壳伸展作用下孕育了第一阶段的正韧性剪切；在地壳收缩作用下的第二阶段完成了韧性推覆到脆性仰冲的转化；而在地壳引张应力场中的第三阶段发生了脆性正断作用。断裂的多期活动形成了小秦岭地区的盆岭构造格架。  相似文献   

THE　EFFECT　OF　THE　NEW　EURASIAN　CONTINENTAL　BRIDGE　ON　THE　EASTERN　COASTAL　AREAS　OF　CHINA     

周建华  姚士谋 《中国地理科学(英文版)》1995,5(3):193-201

ＴＨＥＥＦＦＥＣＴＯＦＴＨＥＮＥＷＥＵＲＡＳＩＡＮＣＯＮＴＩＮＥＮＴＡＬＢＲＩＤＧＥＯＮＴＨＥＥＡＳＴＥＲＮＣＯＡＳＴＡＬＡＲＥＡＳＯＦＣＨＩＮＡＺｈｏｕＪｉａｎｈｕａ（周建华）；ＹａｏＳｈｉｍｏｕ（姚士谋）（ＮａｎｊｉｎｇＩｎｓｔｉｔｕｔｅｏｆＧｅ...  相似文献   

Mantle plume,large igneous province and continental breakup——Additionally discussing the Cenozoic and Mesozoic mantle plume problems in East China   总被引：1，自引：0，他引：1  

李凯明  汪洋  赵建华  赵海玲  狄永军 《地震学报(英文版)》2003,16(3):330-339

Based on the former workers study results such as numerical simulation of fluid mechanics,seismic tomography of the whole earth and igneous rocks,the basic characteristics of mantle plumes are summarized in detail,namely the mantle plume,from the D″layer near the core-mantle bouundary(CMB)of 2900 km deep,is characterized by the spape of large head and thin narrow conduit,by the physical property of high temperature and low viscosity.The LIP(large igneous province)is the best exhibition when the mantle plume ascends to the surface.According to the basic characteristics of the mantle plumes and the LIP,as well as the temporal-spatial relationships between the mantle plume and continental breakup,the detailed research on petrology,geochemistry,temporal-spatial distribution,tectonic background of the Cenozoic-Mesozoic igneous rocks and gravity anomaly distribution in East China has been done.As a result,the Mesozoic igneous rocks in Southeast China should not be regarded as an example of typical LIP related to mantle plumes.for their related characteristics are not consitent with those of the typical LIPs related to mantle plumes.The Cenozoic igneous rocks in Northeast China have no the typical characteristics of mantle plumes and hotspots,so the Cenozoic volcanism in Northeast China might have no the direct relationships with the activity of mantle plumes.  相似文献   

Geochemistry of early Paleozoic alkali dyke swarms in south Qinling and its geological significance   总被引：3，自引：0，他引：3  

张成立  高山  张国伟  柳小明  于在平 《中国科学D辑(英文版)》2003,46(12):1292-1306

The abundant research achievements about Qinling orogeny going through central China were obtained in the last decade[1—3]. However, there is a debate about the early Paleozoic tectonic evolution of south Qinling. Thus, it is undoubted that the systemati…  相似文献   

Ni–Cu–(PGE) magmatic sulfide deposits in the Yangliuping area,Permian Emeishan igneous province,SW China     

Xie-Yan?SongEmail author  Mei-Fu?Zhou  Zhi-Min?Cao  Min?Sun  Yun-Liang?Wang 《Mineralium Deposita》2003,38(7):831-843

The Ni–Cu–PGE sulfide deposits in the Yangliuping area, SW China, are hosted in mafic–ultramafic sills. The four mineralized sills are located in the Yangliuping tectonic dome and intrude Devonian carbonaceous marble, graphitic schist. The sills are 200–300 m thick and 1,000–2,000 m in strike length and now consist chiefly of serpentinite, talc schist, tremolite schist, and meta-gabbro. Disseminated Ni–Cu sulfide mineralisation occurs in the serpentinite in the lower parts of the sills. Massive sulfide mineralisation is located in the base of the sills and in the footwall along fractures beneath the mineralized serpentinite. Although the sulfide ores have been modified by hydrothermal activity, there are relict cumulate textures in the disseminated sulfides indicating a magmatic origin for the ores. The Yangliuping Intrusions and the Dashibao Formation have similar primitive-mantle normalized trace element and platinum group element (PGE) patterns, indicating that they are derived from a common parental magma type. The positive correlation between Cu concentrations and Cu/Zr ratios of the Dashibao Formation basalts indicates that the chalcophile elements were removed before eruption. We propose that fractional crystallization of the Yangliuping magma accompanied by the introduction of S and CO₂ from the wall rocks caused the magma to become S-saturated leading to the segregation of magmatic sulfides that became enriched in Ni–Cu–(PGE). The sills acted as conduits for the overlying Dashibao Formation basalts with the sulfide liquid, along with early crystallizing olivine and pyroxene, segregating from the magma as it passed through the conduits prior to eruption.Editorial handling: H.E. Frimmel  相似文献   

被动大陆边缘：从大陆张裂到海底扩张   总被引：4，自引：0，他引：4  

曹洁冰  周祖翼 《地球科学进展》2003,18(5):730-736

被动边缘是研究大陆张裂、破裂到海底扩张的关键。ODP103、149、173航次对伊比利亚-纽芬兰非火山型共轭边缘的研究,证实了洋陆过渡带和低角度拆离断层的存在,其中洋陆过渡带中广泛出现蛇纹岩化地幔橄榄岩,钻探结果支持不对称单剪模式。ODP104、152、163航次对挪威-格陵兰东南火山型共轭边缘的调查,揭示了典型的向海倾斜反射层（SDRS）的特征,反映了岩浆活动在边缘形成中的主导作用。为了进一步了解大陆从张裂到破裂到洋底扩张过程的一系列学术问题,需要在IODP阶段继续对共轭被动边缘以及包括冲绳海槽和南海在内的典型地区,通过钻探、采样和观测进行更深入的研究。  相似文献   

大陆造山带元古宙构造体制研究的思路和方法探讨──以秦岭造山带为例   总被引：1，自引：0，他引：1  

周鼎武  刘良  刘养杰  董云鹏 《地球科学进展》1996,(2)

根据现代构造理论和大陆地质研究的新进展，以秦岭造山带为例，从稳定地块与造山带的结合、显生宙造山过程对元古宙构造体制的限制、元古宙地层划分对比、元古宙古构造环境分析的地球化学等方面研究入手，对造山带元古宙构造体制研究的思路和方法进行了初步探讨。  相似文献   

扬子地台西缘内带大型铜矿床的“叠加裂谷─多源─热水”成矿作用     

吴健民  黄永平  黎功举 《矿产与地质》1996,(1)

扬子地台西缘的绝大多数大型铜矿床集中在西缘内带，成矿构造环境属川滇叠加裂谷系，它经历了复杂的地质构造演化，产生了“四层楼式”裂谷型铜矿床序列；成矿物质铜以深源为主（上地幔或下地壳），次为浅源（上地壳）和陆源；从元古宙到显生宙，铜矿床由地幔型向幔壳型→壳幔型→壳源型演化；成矿流体包含火山次火山热液、喷流热液、循环热（卤）水和变质－构造热液等多种热水。  相似文献