土被结构系统分类及其应用

提出土被结构是由土壤群体组成且具有整体性、结构性和功能性的耗散系统的观点;以土被结构空间有序为特征,充分考虑土被各种空间基础,即地貌类型,建立土被结构分类系统.并应用这个系统划分了渭南地区土被结构类型系统.     

地幔的窗口：金刚石

从经济价值而言，金刚石是最昂贵的宝石饰品；从科学意义而言，它还是直接可以提供地幔的物理状态与化学组成的窗口。笔者简要介绍了金刚石在自然界的产状、形成条件、不纯净组分、各类包裹体的特征以及成因模型。金刚石最主要的寄主岩为地幔橄榄岩和榴辉岩。金刚石中的同生包裹体可以为其形成时的寄主岩组成、温压条件、在地幔中的存留年龄提供重要的依据。近20多年来在金刚石中发现了深达下地幔的超深矿物包裹体，它又成为了认识全部地幔物质组成的唯一窗口。     

基于横波分裂方法的海南地幔柱研究

利用横波分裂方法,对北京大学、南方科技大学及桂林理工大学在广东和广西布设的宽频带流动台阵以及国家地震台网在广东、广西和海南的固定台站记录的XKS震相进行计算,得到海南及邻近地区的上地幔各向异性参数,分裂延迟时间在0.35～1.90s之间.综合研究区域内前人发表的和本文的横波分裂结果,认为自新生代以来,伴随东部太平洋板块...     

南海玄武岩：扩张洋脊与海山

 南海存在两种火山岩：洋中脊玄武岩（MORB）和洋岛玄武岩（OIB）。国际大洋发现计划（IODP）第349、367、368、368X航次在南海海盆的成功钻取,获得了南海初始扩张（~34 Ma）和停止扩张（~15-16 Ma）前的洋壳样品。南海东部、西南次海盆及北缘洋-陆过渡带代表海盆发展的不同阶段,具有不同的地幔潜能温度、物质组成和洋脊扩张速度,因此产生的洋中脊玄武岩成分差异显著。南海地区在扩张晚期及停止扩张之后存在大规模地幔上涌,与其周缘地区的持续俯冲有关,产出的海山OIB不同于地幔柱活动产生的火山链。南海虽小,但蕴含的信息异常丰富,是窥探地球深部难得的天然窗口。     

Re-Os dating of the Raobazhai ultra mafic massif in North Dabie

The ultramafic massif at Raobazhai in North Dabie is located in the suture zone between the Yangtze craton and North China eraton. The Re-Os isotope compositions of the massif are used to decipher the origin and tectonics of the ultramafic rocks involved in continental subduction and exhumation. Fifteen samples were collected from five drill holes along the main SE-NW axis of the Raobazhai massif. Major and trace element compositions of the samples show linear correlations between MgO, Yb and Al_2O_3. This suggests that the massif experienced partial melting with variable degrees and is from fertile to deplete in basaltic compositions. Nine selected samples were analyzed for Re-Os isotope compositions. Re contents range from 0.004 to 0.376 rig/g, Os contents from 0.695 to 3.761 ng/g, ~(187)Re/~(188)Os ratios from 0.022 to 2.564 and ~(187)Os/~(188)Os ratios from 0.1165 to 0.1306. These indicate that the massif is a piece of continental lithospheric mantle with variable depletion. Using the positive corre     

Chondritic osmium isotopic composition of late Archean convecting upper mantle：Evidence from Zunhua podiform chromitites,Hebei, North China

The Os isotopic composition and evolution of con-vecting upper mantle (CUM) are an important and diffi-cult scientific issue related to the distributions of PGEs inearth’s interior and the accretion history of the earth. De-termination of 187Os/188Os of modern CUM has been at-tempted via analyses of abyssal peridotites, mid-oceanridge basalts (MORB), MORB glasses and sulfides. Abyssal peridotites, which are mantle samples re-covered from the ocean ridges, represent the upperm…     

金属离子对皱纹盘鲍组织培养的影响

采用3因素3水平L9（3^4）的正交设计，以组织块增殖百分率作为评价指标，研究了在M199和RPMI-1640培养基中分别添加Ca^2＋，Mg^2＋，Zn^2＋金属离子对鲍的外套膜和上足触手组织培养的影响．结果显示，Ca^2＋和Zn^2＋对细胞增殖具有明显的促进作用，Mg^2＋的作用不明显；对上足触手细胞生长最好的组合为5g／L的Ca^2＋，1g／L的Mg^2＋，20μg/L的Zn^2＋；对外套膜细胞生长最好的组合为1g／L的Ca^2＋，1g／L的Mg^2＋，60μg／L的Zn^2＋．     

Mantle plumes： Why the current skepticism？

The present reappraisal of the mantle plume hypothesis is perhaps the most exciting current debate in Earth science. Nevertheless, the fundamental reasons for why it has arisen are often not well understood. They are that 1） many observations do not agree with the predictions of the original model, 2） it is possible that convection of the sort required to generate thermal plumes in the Earth＇s mantle does not occur, 3） so many variants of the original model have been invoked to accommodate conflicting data that the plume hypthesis is in practice no longer testable, and 4） alternative models are viable, though these have been largely neglected by researchers. Regardless of the final outcome, the present vigorous debate is to be welcomed since it is likely to stimulate new discoveries in a way that unquestioning acceptance of the conventional plume model will not.