Continental recycling and true continental growth   总被引：1，自引：0，他引：1  

Tsuyoshi Komiya 《Russian Geology and Geophysics》2011,52(12):1516-1529

Continental crust is very important for evolution of life because most bioessential elements are supplied from continent to ocean. In addition, the distribution of continent affects climate because continents have much higher albedo than ocean, equivalent to cloud. Conventional views suggest that continental crust is gradually growing through the geologic time and that most continental crust was formed in the Phanerozoic and late Proterozoic. However, the thermal evolution of the Earth implies that much amounts of continental crust should be formed in the early Earth. This is “Continental crust paradox”.Continental crust comprises granitoid, accretionary complex, and sedimentary and metamorphic rocks. The latter three components originate from erosion of continental crust because the accretionary and metamorphic complexes mainly consist of clastic materials. Granitoid has two components: a juvenile component through slab-melting and a recycling component by remelting of continental materials. Namely, only the juvenile component contributes to net continental growth. The remains originate from recycling of continental crust. Continental recycling has three components: intracrustal recycling, crustal reworking, and crust–mantle recycling, respectively. The estimate of continental growth is highly varied. Thermal history implied the rapid growth in the early Earth, whereas the present distribution of continental crust suggests the slow growth. The former regards continental recycling as important whereas the latter regarded as insignificant, suggesting that the variation of estimate for the continental growth is due to involvement of continental recycling.We estimated erosion rate of continental crust and calculated secular changes of continental formation and destruction to fit four conditions: present distribution of continental crust (no continental recycling), geochronology of zircons (intracontinental recycling), Hf isotope ratios of zircons (crustal reworking) and secular change of mantle temperature. The calculation suggests some important insights. (1) The distribution of continental crust around at 2.7 Ga is equivalent to the modern amounts. (2) Especially, the distribution of continental crust from 2.7 to 1.6 Ga was much larger than at present, and the sizes of the total continental crust around 2.4, 1.7, and 0.8 Ga became maximum. The distribution of continental crust has been decreasing since then. More amounts of continental crust were formed at higher mantle temperatures at 2.7, 1.9, and 0.9 Ga, and more amounts were destructed after then. As a result, the mantle overturns led to both the abrupt continental formation and destruction, and extinguished older continental crust. The timing of large distribution of continental crust apparently corresponds to the timing of icehouse periods in Precambrian.  相似文献   

中国地质标准物质文献(1980~2010)综述   总被引：3，自引：1，他引：2  

王毅民  王晓红  高玉淑  樊兴涛 《地质通报》2011,30(9):1450-1461

评介了20世纪80年代中国首批地质标准物质诞生以来发表的有关地质标准物质的文献,包括:综合性评述,研制成果总结,样品加工、粒度检测、均匀性检测、稳定性检测评价、定值方式方法、不确定度评价、量值溯源等制备技术方法的研究与评述,研制工作的其它评述、专著等。最后对比了国内外地质标准物质的文献状况。  相似文献   

极低放废物近地表处置的环境安全评价方法研究     

滕彦国  左锐  王金生 《矿物岩石地球化学通报》2011,30(1):59-64

放射性废物处置是当前严峻的环保问题之一,从经济、安全和高效角度出发,将极低放废物从中、低放废物中分离出来单独处置,对核废物的管理与处置具有重要意义。本文以我国西南某极低放废物备选处置场为研究对象,系统分析了处置的相关技术方法,重点研究了屏障技术和环境安全评价方法及其应用。针对拟建在古泥石流体山区山顶上的处置场,选取核素90Sr作为处置对象,选用盆状屏障式处置库,估算产生的核素90Sr的总活度和比活度。选用筛分的颗粒d<1 mm的介质作为屏障材料,厚度为0.5 m,批试验结果显示上述材料对90Sr的吸附效果明显;模拟计算结果显示核素90Sr在50 a内被完全阻滞在包气带中,可以达到安全处置废物的要求。  相似文献   

Dispersal and fate of dredged materials disposed of in the Changjiang Estuary determined by use of an in situ rare earth element tracer     

刘高峰  吴华林  郭文华  朱建荣  孙连成 《中国海洋工程》2011,25(3):495-506

To investigate the dispersal pattern and the fate of dredged materials disposed at a pre-selected disposal site, a field tracer experiment was conducted in the North Passage of the Changjiang Estuary during the 2005 flood season. Three tons of dredged materials were mixed with 2.792 kg of sodium hexachloroiridate (IV) hexahydrate (SHH), which contained the rare earth element tracer iridum (Ir). Sampling was conducted at pre-selected sections of the estuary on the second, third and fourth day after the release of dredged materials. All samples were evaluated by use of neutron activation analysis. The majority of the dredged material was dispersed nearly parallel to the navigation channel and deposited between the channel and the south dike. Only a small quantity of dredged materials entered or crossed the navigation channel, and the back silting ratio in the navigation channel was about 5%. The dredged materials also dispersed southeasterly beyond two dike heads.  相似文献   

标准海水研究现状及其应用     

赵卓英  田孟安  孙浩  胡波 《海洋通报》2011,30(3):283-286

标准海水作为海水盐度量值的标准物质,广泛用于检定和校准海水盐度测量仪器和装置.主要介绍两种标准物质-中国-级标准海水和中国系列标准海水,系统介绍我国现阶段标准海水的制备,封装工艺,保存方法,并阐述其在使用过程中的注意事项.  相似文献   

海洋动物标准物质的研制及其技术流程     

吕海燕  王正方  周青松  刘际弟 《海洋学研究》2011,29(1):104-108

以缢蛏为例,详细介绍了海洋动物标准物质的研制及其技术流程,对研制过程中候选物的确定,以及标准物质所必须具备的特性量值等进行了全面叙述.海洋动物标准物质制备的技术流程主要包括:均匀性、稳定性和准确性的检验,定值分析方法、数据的统计分析以及定值数据结果的表达.有证标准物质的包装运输、认定证书和标签等方面的操作也都应按照规定...  相似文献   

玄武岩纤维原料特征的统计及分析研究     

李珎  徐冠立  刘荣  史凯文 《地质论评》2024,70(1):262-276

玄武岩纤维是以玄武岩或他种成分相近的岩石为主要原料,经熔融后拉制而成的一种高性能纤维。天然矿石的成分波动会造成拉丝困难或纤维性能不稳定,笔者等收集了54组原料岩石以及114组玄武岩纤维样品的化学成分数据,研究归纳了玄武岩纤维所需原料的岩石学特征、参数指标特征和其他特征,分析提出了可拉丝岩石相关参数指标的最佳区间。适于生产玄武岩纤维的原料矿石,其特征可总结如下：岩石学方面,以基性岩以及SiO2含量为53%~57%的中性岩为佳,岩石类型最佳为玄武岩或安山玄武岩;岩石结构最佳为间隐结构、玻基斑状结构或玻璃质结构;构造的影响是间接的,主要为气孔或杏仁构造中可能含有的一些不利矿物的影响;矿物组成方面,蛇纹石、沸石等含水矿物会在熔融过程中产生气泡,影响纤维制备连续性的同时也有利于原料的充分熔融,镁橄榄石、磁铁矿等高熔点矿物会使原料在熔融阶段难以完全熔化,导致熔体不均匀并容易析晶。参数指标方面,可拉丝岩石的酸度系数（Mk）最佳区间为4. 0~5. 5;黏度系数（Mv）为2. 0~3. 0;硅铝氧化物与其他氧化物比值为1. 5~3. 0;氧化物组成的物质的量分数分布为n(RO)=20%~30%,n(RO2)=57%~70%,n(R2O3)=10%~16%（R为阳离子）。  相似文献   

基于可拓工程法的黄土路堑边坡稳定性评价方法   总被引：3，自引：0，他引：3  

王东耀  折学森  叶万军 《地球科学与环境学报》2006,28(3):57-60

针对影响黄土路堑边坡稳定性因素的复杂性和模糊性,重视实践中的经验,将可拓工程方法与路堑边坡稳定性评价相结合,提出了路堑边坡稳定性评价的物元关联函数及物元关联度的计算方法。建立了适合可拓学理论的边坡稳定性分类标准,实现了定性与定量评价黄土路堑边坡的结合。实例评价结果与定值计算、工程实际调查结果一致。  相似文献   

Motive force of Qinghai-Tibet Plateau moving to east     

YANG Dong-hong YANG Xue-xiang  CHEN Dian-you College of Geo-Exploration Science  Technology  Jilin University  Changchun  Jilin  China National Astronomical Observatories  Chinese Academy of Science  Beijing  Changchun  Jilin  China College of Mathematics Science  Jilin University  Changchun  Jilin  China 《东北亚地学研究》2005,(Z1)

A calculation formula on spherical pattern of Qinghai-Tibet plateau moving model is established, Tibet massif moves norward by east in speed of 28 mm/a, Ganshu-Qinghai massif moves to northeast in speed of 15 mm/a, Qomolangma Feng moves northward by a few east in speed of 35 -42 mm/a. The low latitude perimeter is longer than the high latitude perimeter. When the Tibet massif moves northward, its latitude perimeter must be contracted and the Tibet massif must move eastward by Coriolis. Coriolis force is inertial in earth rotation. It makes the fall body turning to east and the rising block turning westward. In the Northern Hemisphere, it makes the northward body turning to east and the southward block turning to west. This is the reason why the tectonic zones of western Pacific are different from those of eastern Pacific.  相似文献   

应用新古典增长模型研究湛江经济发展问题     

李飞星  王波 《广东海洋大学学报》2005,25(5):60-64

运用产出增长率模型对湛江的主要行业的增长率和劳动份额进行了测算,分析了湛江经济增长不均衡及其经济增长率低下的原因,并提出了以工业为主导、发展旅游、贸易、农林牧副渔资源加工等资金积累型产业和加速农村城镇化和机械化的见解。  相似文献