Relationships between carbon isotope evolution and variation of microbes during the Permian–Triassic transition at Meishan Section, South China

This paper investigates kerogen carbon isotopes, the difference between carbonate and kerogen carbon isotopes (Δ¹³C_carb-kero = δ ¹³C_carb − δ ¹³C_kero) and the difference between carbonate and n-C₁₉ alkane compound-specific carbon isotopes (Δ¹³C_carb-n-C19 = δ ¹³C_carb − δ ¹³C _n-C19) during the Permian–Triassic transition at Meishan, South China. The results show that kerogen carbon isotopes underwent both gradual and sharp shifts in beds 23–25 and 26–29, respectively. The differences between carbonate and organic carbon isotopes, both the Δ¹³C_carb-kero and Δ¹³C_carb-n-C19, which are mainly affected by CO₂-fixing enzyme and pCO₂, oscillated frequently during the Permian–Triassic transition. Both the variations of Δ¹³C_carb-n-C19 and Δ¹³C_carb-kero coupled with the alternation between cyanobacteria and green sulfur bacteria indicated by biomarkers. The episodic low values of Δ¹³C_carb-n-C19 corresponded to episodic blooms of green sulfur bacteria, while the episodic high values of Δ¹³C_carb-n-C19 corresponded to episodic blooms of cyanobacteria. The relationships between the variation of carbon isotopes and biota show that the microbes which flourished after the extinction of macroorganism affected the carbon isotope fractionation greatly. Combining the carbon isotope compositions and the pattern of size variation of the conodont Neogondolella, this paper supposes that anoxia of the photic zone at bed 24 was episodic and it would be caused by the degradation of terrigenous organic matters by sulfate reducing bacteria in the upper water column. Considered together with results from previous research, the high resolution variation of the biogeochemistry presents the sequence of the important geo-events during the Permian–Triassic crisis.     

基于GIS的雷电灾害监测预警与数据处理系统

针对雷电灾害涉及的关键问题,基于ArcEngine开发平台,结合大型网络数据库sqlServer2005与空间数据库模型GeoIataBase,设计了具有3层逻辑结构的系统构架方案,构建了基于GIS的雷电监测预警与数据处理系统。该系统有效地将各种雷电数据与GIS平台进行无缝对接,并整合雷电预测模式,实现各种雷电数据基于GIS的实时监测处理与预测预警以及高效组织、存储与管理,满足各种雷电信息查询处理分析的需求;为气象部门对雷电灾害天气的监测、预报预警以及各种数据基于地理信息的处理分析等提供了有效的可视化平台,同时也为GIS与气象专业领域的结合进行了有益的探索。     

从2009年度Nature杂志看气候变化研究进展

<正>英国Nature杂志是世界著名的自然科学类综合学术期刊,代表着自然科学各门学科的最前沿研究动态。在大气科学及相关领域研究中,气候变化一直是Nature杂志最关心的内容。随着气候变化加剧、社会瞩目度的不断上     

广西龙州地区双层含铝岩系地质特征与找矿意义

对龙州地区合山组和都安组铝土岩（矿）层进行系统采样分析，并与堆积铝土矿进行对比研究，结合含铝岩系岩性与矿物特征发现，合山组、都安组铝土岩（矿）矿石矿物无显著差异，主要为一水硬铝石、高岭石、（鲕）绿泥石，其次为赤铁矿（针铁矿）集合体和碎屑物（岩屑、玻屑、砾屑），普遍存在大量（铁）凝胶。常量、微量、稀土元素特征及相关图解显示，合山组、都安组铝土岩（矿）均可能为该区堆积铝土矿的矿源层。Ni-Cr图解显示合山组铝土岩（矿）可能来自与火山物质有关的玄武岩，都安组铝土岩（矿）来源于卡斯特岩溶，堆积铝土矿除部分落入玄武岩、碳酸盐岩区以外，大多位于页岩、板岩内，表明该区堆积铝土矿存在多源性。微量元素Be、Ga、Sr、Ba含量与Sr/Ba、V/Zr、Zr/Cu含量比值等沉积环境元素特征表明该区原生铝土岩（矿）沉积环境为陆相；δCe分析显示铝土岩（矿）沉积环境有所差异，合山组表现为氧化环境，都安组则表现为还原环境。Th、U含量及Th/U含量比值显示该区铝土岩（矿）成矿以混合作用为主，并经历了较强的风化作用；δEu分析表明合山组、都安组铝土岩（矿）分别形成于被动大陆边缘与活动大陆边缘。合山组、都安组含铝岩系均发育不同程度的铝土岩（矿）层，都安组铝土岩（矿）部分样品已达工业边界指标，可作为沉积铝土矿勘查的主要目的层。     

The color properties of compact groups of main galaxies from the SDSS Data Release 4

In order to compare color statistical properties of member galaxies in compact groups with those of field galaxies, we use a compact group (CG) sample which contains 4217 CGs extracted from the MAIN galaxy sample of the SDSS Data Release 4 (SDSS4), and construct a random group sample which has the same distributions of redshift and number of member galaxies as those of the CG sample. It turns out that the mean colors of galaxies in CGs are redder than those of galaxies in random groups. Additionally, we also find that member galaxies in real CGs have a smaller dispersion of colors than those in random groups-at least for g-r, r-i, and i-z colors. Published in Astrofizika, Vol. 50, No. 1, pp. 29–37 (February 2007).     

Collocation-PECE�㷨�ڵ͹����Ǿ��ܶ����е�Ӧ��

???????????У?PECE????????????????????????????Collocation????????????????幫??????????μ?PECE???????????????????ж??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????Adams-PECE????????PECE?????????????????????????????,???????????Collocation-PECE??????????????н???????????????Ч??     

一维渗透固结中排水边界生成与识别的初步探讨

本文首先分析了内部与表部土层生成排水边界时的渗流方向并提出了绝对与相对排水边界的概念;然后分别讨论了绝对与相对排水边界的识别标准.     

The Cenozoic mantle magmatism and motion of lithosphere on the north margin of the Tibetan Plateau

Geodynamic properties and evolution of the lithosphere on the north margin of the Tibetan Plateau are recently hot topics to geoscientists in the world. Have the northern plates been subducting underneath the Plateau? It is still an unsolved problem. One of the keys to solving this problem is to understand the genetic processes of Cenozoic magmas on the north margin of the Tibetan Plateau. However, there is no enough evidence supporting the subduction model. In contrast, a series of evidence indicates that collision-induced huge shearing faults and large-scale crust shortening played a main role in lithosphere motion on the north margin of the Tibetan Plateau. The mantle-derived igneous rocks strictly distribute at the intersections of large strike-slip faults on the north margin of the Plateau. Generation of magmas may be related to local extensional condition induced by strike-slipping faults, which lead to lithosphere gravitational instability and collapse, as well as upwelling of the deep hot material. Heat induced by shearing and carried by upwelling hot material may cause partial melting on H₂O-bearing mantle.     

A CADASTRAL SPATIAL DATA STORAGE STRUCTURE BASED ON RELATIONAL DATABASE

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一个罕见的铀钨矿物组合

本文首次报导钨锰矿和铀矿物在空间上叠生的现象。这种叠生现象出现在一种很特别类型的矿床中，与传统的铀钨伴生理论有悖，这种铀、钨叠生矿化不仅具有重要的经济价值，而且也会拓展铀、乌伴生理论的研究。