Quantifying the variability and allocation patterns of aboveground carbon stocks across plantation forest types,structural attributes and age in sub-tropical coastal region of KwaZulu Natal,South Africa using remote sensing

Quantifying the variability and allocation patterns of aboveground carbon stocks across plantation forests is central in deriving accurate and reliable knowledge and understanding of the extent to which these species contribute to the global carbon cycle and towards minimizing climate change effects. The principal objective of this study was to quantify the variability and allocation patterns of aboveground carbon stocks across Pinus and Eucalyptus plantation forests, tree-structural attributes (i.e. stems, barks, branches and leaves) and age groups, using models developed based on remotely sensed data. The results of this study demonstrate that aboveground carbon stocks significantly (α = 0.05) vary across different plantation forest species types, structural attributes and age. Pinus taeda and Eucalyptus grandis species contained aboveground carbon stocks above 110 t C ha⁻¹, and Eucalyptus dunii had 20 t C ha⁻¹. Across plantation forest tree structural attributes, stems contained the highest aboveground carbon stocks, when compared to barks, branches and leaves. Aboveground carbon stock estimates also varied significantly (α = 0.05) with stand age. Mature plantation forest species (i.e. between 7 and 20 years) contained the highest aboveground carbon stock estimates of approximately 120 t C ha⁻¹, when compared to younger species (i.e. between 3 and 6 years), which had approximately 20 t C ha⁻¹. The map of aboveground carbon stocks showed distinct spatial patterns across the entire study area. The findings of this study are important for understanding the contribution of different plantation forest species, structural attributes and age in the global carbon cycle and possible climate change moderation measures. Also, this study demonstrates that data on vital tree structural attributes, previously difficult to obtain, can now be easily derived from cheap and readily-available satellite data for inventorying carbon stocks variability.     

胶西北地区北截金矿闪长玢岩锆石SHRIMP年龄及其地质意义

山东省招远市北截金矿是胶西北地区发现较早的金矿之一,主要赋存于严格受NEE向断裂控制的黄铁绢英岩化蚀变带内,是典型的破碎带蚀变岩型金矿。本文通过对矿区内切穿矿体的闪长玢岩、郭家岭序列下属北截岩体的地质背景和SHRIMP锆石U-Pb年代学研究,得出闪长玢岩形成年龄为117±2Ma,北截岩体形成年龄为129±1Ma,限定北截金矿成矿年龄在117~129Ma之间,属早白垩世。锆石样品中测得Ar_3、Z、J_3等多个期次的继承锆石年龄,表明北截岩体和闪长玢岩形成过程具有多重继承演化性。根据同源岩浆的成岩成矿时间差及岩体与金矿的空间位置,判断郭家岭序列与金矿关系更为密切。讨论了胶东金矿的成矿期次和构造环境,认为其形成于俯冲造山带的弧后伸展环境,其形成与演化受中生代以来中国东部岩石圈大规模减薄、地幔上涌或陆缘裂谷的影响,最终成因可能与地幔柱有关。     

华北克拉通五台群LA-ICP-MS锆石U-Pb年龄和Hf同位素特征

通过对五台群石咀亚群金刚库组4个典型样品的LA-ICP-MS锆石U-Pb年龄和Hf同位素研究,对五台群的形成时代及华北克拉通新太古代—古元古代期间的地壳演化进行了探讨。锆石U-Pb同位素测定结果表明,侵入金刚库组中的片麻状花岗岩锆石的U-Pb年龄为2548Ma,因此五台群的上限年龄约为2.5Ga;金刚库组黑云母石英片岩和片麻状石英闪长岩的原岩锆石U-Pb年龄分别为2663Ma和2636Ma,因此五台群的下限年龄约为2.7Ga。五台群的地质年龄为2.5~2.7Ga,属于新太古代。锆石Hf同位素研究结果表明,黑云母石英片岩和片麻状石英闪长岩的二阶段Hf模式年龄(tDM2)均为2.8Ga左右,指示2.8Ga左右是五台山区乃至整个华北克拉通地壳生长的重要时期;片麻状花岗岩tDM2平均为2.57Ga,与锆石结晶年龄非常接近,表明2.5Ga左右也是华北克拉通地壳的主要增生期。地壳的增长是幕式的,2.8Ga和2.5Ga都是华北克拉通地壳生长时期。     

NGC 1624 (OCl 403, Cr 53) – A very young open cluster

We present the first CCD photometric UBVRI observations of the not-so-well-studied open cluster NGC 1624 (OCl 403, Cr 53; α₂₀₀₀ = 04 h 40 m 36 s; δ₂₀₀₀ = + 50^˚ 27^′ 42″ Trumpler class = I 2 p N). This cluster was observed on 01 February 2004 with the 2 m Himalayan Chandra Telescope at Hanle using a LN2 cooled 2k × 2k CCD. The cluster presents differential reddening with E(B-V) values ranging from 0.70 to 0.90 mag, which could be attributed to the presence of the HII region wherein the cluster is embedded. It is found to be at a distance of 6.025 ± 0.5 kpc and the age of this cluster is estimated to be ∼3.98 × 10⁶ years. In view of these parameters, it can be considered as a young enough cluster located in the direction of the Perseus constellation with the galactic coordinates of l = 155^˚.35 and b = + 02 ^˚.58. Thus it could also be used as a suitable candidate for tracing the Outer Perseus spiral arm of our Galaxy. The initial mass function slope is derived as 1.65 ± 0.25 by applying the corrections for field star contamination and data incompleteness. This is in good agreement with the Salpeter value within the limits of errors.     

河南西峡北部燕山期岩浆热液型矿床及其侧向分带

西峡县北部有一巨大的与燕山期岩浆活动有关的热液活动成矿带。从岩浆活动中心向南的成矿可依次分为：内带—中带—外带，其对应主成矿元素为：Ｍｏ、Ｗ－Ａｕ、Ｐｂ、Ａｇ－Ａｕ、Ｓｂ、Ａｓ，中带和外带为金的重要成矿带。矿带与燕山期侵入体空间依存关系密切，成生时代一致。分带为由岩浆活动中心向外热液温度的降低及扩散距离的远近所造成，它可存在于地质体不同规模的尺度上，在东秦岭较为普遍。研究这种分带，对矿产的预测与评价将会有较大的帮助     

北秦岭官坡地区柯石英榴辉岩变质作用的P－T－t轨迹

根据矿物包裹和替代关系以及共生组合规律，北秦岭官坡地区柯石英榴辉岩的变质作用演化可划分为５个阶段，即前榴辉岩相的绿帘角闪岩相、榴辉岩相、后榴辉岩相的角闪岩相、绿帘角闪岩相和绿片岩相。Ｓｍ－Ｎｄ同位素定年显示，北秦岭柯石英榴辉岩于４００±１６Ｍａ沿朱夏断裂被推覆上升，Ｐ－Ｔ－ｔ轨迹的地球动力学成因可能与扬子和华北陆块间的俯冲－碰撞作用有关。     

U-Pb zircon ages for the Luzhenguan Complex in northern part of the eastern Dabie orogen

The Dabie Mountain is the collisional orogenic belt between the North China Block and the Yangtze Block. As the eastern segment of the central-China orogenic belt, its tectonic framework is corresponding to the Qinling orogenic belt as a whole[1]. The NHB in northern part of Dabie Orogen is regarded as the joint belt between the Yangtze Block and the North China Block, and roughly corresponds to the north Qinling belt of the Qinling orogenic belt, which separated the Tongbai-Dabie hig…     

THE DEMOGRAPHIC CONSEQUENCES OF METROPOLITAN POPULATION DECONCENTRATION IN THE U.S.

Although the recent growth in the nonmetropolitan population of the U.S. is now well documented, little attention has been given to the consequences these trends will have on the future composition and growth of metropolitan and nonmetropolitan regions. This paper discusses the feedback effects of migration on the future age structure and population growth of both regions during the period 1975–2000.     

锆石红外光谱在地质研究中的应用

以甘肃白银厂地区的7件锆石同位素年龄样品为例,根据其红外光谱中615cm-1吸收峰的高和半高宽度的比值,将锆石样品的变生程度量化,并将其分为晶质锆石、半变生锆石和变生锆石3类。参考相关资料,利用7件锆石样品的红外光谱特征对其铀钍含量和"红外年龄"做了估测,并将估测年龄与其U Th年龄和全岩Rb Sr年龄进行了比较和分析。