青藏高原东南缘地貌边界性质的界定及其对高原东南缘扩展模式的启示

青藏高原东南部的地貌结构是高原隆升深部动力过程与高原扩展的重要指标之一,存在受下地壳流驱动的渐变模型和受宽约50～200km的雅砻-玉龙断裂系控制的陡变模型2种不同认识。文中基于30m分辨率的SRTM数据进行数字高程分析,利用高程和水系参数对研究区地貌加以提取和分析,结合野外地貌和构造调研的结果以及前人的相关研究,对高原东南缘川滇地块中部构造地貌细结构进行了详细的解析。研究认为,青藏高原东南边界具有明显的台阶式构造地貌结构,不同台阶梯度带受不同时期发育的NE-SW向断裂控制。其中一级边界位于木里-玉龙断裂,控制了平均海拔4 200m的高原面的东南边界,是渐新世—中新世早期构造抬升的结果;二级边界受中新世中期逆冲活动的金河-箐河断裂控制,其构成丽江—盐源一带海拔中等(约3 000m)、相对低起伏区域的东南边界。高原东南边界的台阶式构造地貌结构反映了高原向SE的前展式逆冲扩展。这种扩展模式并不支持下地壳管道流连续变形模型。     

利用接收函数方法研究青藏高原东南部地壳结构

青藏高原东南部作为板块碰撞的前缘地带一直是地球科学研究的热点,为了揭示碰撞前缘地带地壳结构特征,作者 利用布设在中国青藏高原东南部的38个宽频带流动台站记录的2487条远震P波接收函数,采用接收函数CCP叠加（共转换点 叠加）和H-κ叠加两种方法获得了研究区域详细的地壳厚度图像和泊松比值。研究结果显示：两种方法获得的地壳厚度特征 具有较好的一致性;青藏高原东南部地壳厚度存在明显的东西差异和南北差异;喜马拉雅构造区内莫霍面深度变化较大, 介于65~80 km之间;拉萨地体内莫霍面深度介于72~80 km之间;雅鲁藏布缝合带两侧地壳厚度突变,缝合带北侧和南侧地 壳厚度相差约8 km。研究区域平均泊松比值较小,为0.24,和大多数造山带泊松比偏低的特征类似。研究区域中下地壳广 泛存在强转换界面,该界面可能对应中下地壳高速层的上界面,埋深40~70 km,表明壳内发生深熔或部分熔融作用,导致 壳内发生重力分异,在中下地壳形成了高速薄层。     

1990-2050年间贵州省东南部森林植被碳蓄积及固碳潜力分析

本文以贵州省东南部三州为研究区,运用连续生物量转换因子法和平均生物量法,通过2010年森林清查小班数据,建立了24类优势树种的森林植被碳密度与林龄之间的关系。同时,估算了1990-2010年间贵州省东南部森林植被生物量及其碳蓄积量,分析了碳蓄积量的时空变化特征,并预测出2050年该区域森林植被的固碳潜力。结果显示：（1）2010年贵州省东南部森林植被碳蓄积量为106.22 TgC,占贵州省森林植被碳蓄积量的63.01%,占全国森林植被碳蓄积量的1.36%;平均碳密度32.44 MgC/hm²,是贵州省森林植被平均碳密度的93%,全国森林植被平均碳密度的76%,碳密度空间分布呈现由西部向东部增加趋势且东部高于平均水平。（2）1990-2000年间森林植被碳蓄积量增加了30.67 TgC;2000-2010年间森林植被碳蓄积量增加了49.55 TgC,其中,退耕还林导致森林植被碳蓄积量增加了31.09 TgC。（3）以2010年为基准年,假设40 a后贵州省东南部森林面积保持稳定,且不考虑轮伐期的未来情景下,至2050年该区域森林植被碳蓄积量将达到153.38 TgC,其增量可达47.16 TgC,表明贵州省东南部森林具有较大的碳增汇潜力。     

腾格里沙漠东南缘4种灌木的生物量预测模型

灌木生物量模型是预测灌木生物量最有效的方法。选择腾格里沙漠南缘荒漠生态系统中常见的4种灌木（驼绒藜(Ceratoides latens)、盐爪爪(Kalidium foliatum)、珍珠猪毛菜(Salsola passerina)、红砂(Reaumuria soongarica)）为研究对象,以株高（H）和冠幅（C）的复合因子灌木体积（V）为自变量,通过回归分析,分别构建了4种灌木和混合物种的叶、新生枝、老龄枝、地上部分、地下部分和整株生物量的预测模型。通过决定系数（R2）、估计值的标准误（SEE）和回归检验显著水平（p＜0.05）筛选出了最优的生物量估测模型。结果显示:4种灌木的生物量模型主要以幂函数W=aVb为最优模型,少数以三次函数W=a+bV+cV2+dV3为最优模型。灌木生物量与V之间呈极显著的相关关系（p＜0.001）,决定系数较高,分别为:叶片（0.775＜R2＜0.866）,新生枝（0.694＜R2＜0.840）,老龄枝（0.819＜R2＜0.916）,地上部（0.832＜R2＜0.917）,地下部分（0.74＜R2＜0.808）,全株（0.811＜R2＜0.912）,说明预测模型可以应用于此4种灌木的生物量估算。不同物种之间及不同器官之间的生物量模型存在差异,在实际使用中,要根据物种来选择相应的模型。生物量模型的建立有助于全面估算荒漠生态系统的生物量,并进一步评估生态系统不同碳库的碳存储量与碳循环。为有效提高荒漠草地碳储量、合理实施生态系统管理和人为干预提供科学依据。     

Mid to late Paleozoic shortening pulses in the Lachlan Orogen,southeastern Australia: a review

In the late Silurian, the Lachlan Orogen of southeastern Australia had a varied paleogeography with deep-marine, shallow-marine, subaerial environments and widespread igneous activity reflecting an extensional backarc setting. This changed to a compressional–extensional regime in the Devonian associated with episodic compressional events, including the Bindian, Tabberabberan and Kanimblan orogenies. The Early Devonian Bindian Orogeny was associated with SSE transport of the Wagga–Omeo Zone that was synchronous with thick sedimentation in the Cobar and Darling basins in central and western New South Wales. Shortening has been controlled by the margins of the Wagga–Omeo Zone with partitioning along strike-slip faults, such as along the Gilmore Fault, and inversion of pre-existing extensional basins including the Limestone Creek Graben and the Canbelego–Mineral Hill Volcanic Belt. Shortening was more widespread in the late Early Devonian to Middle Devonian Tabberabberan Orogeny, with major deformation in the Melbourne Zone, Cobar Basin and eastern Lachlan Orogen. In the eastern Melbourne Zone, structural trends have been controlled by the pre-existing structural grain in the adjacent Tabberabbera Zone. Elsewhere Tabberabberan deformation involved inversion of pre-existing rifts resulting in a variation in structural trends. In the Early Carboniferous, the Lachlan Orogen was in a compressional backarc setting west of the New England continental margin arc with Kanimblan deformation most evident in Upper Devonian units in the eastern Lachlan Orogen. Kanimblan structures include major thrusts and associated fault-propagation folds indicated by footwall synclines with a steeply dipping to overturned limb adjacent to the fault. Ongoing deformation and sedimentation have been documented in the Mt Howitt Province of eastern Victoria. Overall, structural trends reflect a combination of controls provided by reactivation of pre-existing contractional and extensional structures in dominantly E–W shortening operating intermittently from the earliest Devonian to Early Carboniferous.     

Carboniferous–Permian Stratigraphy and Sedimentary Environment of Southeastern Inner Mongolia, China: Constraints on Final Closure of the Paleo-Asian Ocean

In this paper we discuss the timing of final closure of the Paleo-Asian Ocean based on the field investigations of the Carboniferous–Permian stratigraphic sequences and sedimentary environments in southeastern Inner Mongolia combined with the geology of its neighboring areas. Studies show that during the Carboniferous–Permian in the eastern segment of the Tianshan-Hinggan Orogenic System, there was a giant ENE–NE-trending littoral-neritic to continental sedimentary basin, starting in the west from Ejinqi eastwards through southeastern Inner Mongolia into Jilin and Heilongjiang. The distribution of the Lower Carboniferous in the vast area is sparse. The Late Carboniferous or Permian volcanic-sedimentary rocks always unconformably overlie the Devonian or older units. The Upper Carboniferous–Middle Permian is dominated by littoral-neritic deposits and the Upper Permian, by continental deposits. The Late Carboniferous–Permian has no trace of subduction-collision orogeny, implying the basin gradually disappeared by shrinking and shallowing. In addition, it is of interest to note that the Ondor Sum and Hegenshan ophiolitic mélanges were formed in the pre-Late Silurian and pre-Late Devonian respectively, and the Solonker ophiolitic mélange formed in the pre-Late Carboniferous. All the evidence indicates that the eastern segment of the Paleo-Asian Ocean had closed before the Late Carboniferous, and most likely before the latest Devonian (Famennian).     

岷县漳县6.6级地震后申都乡地窖宏观异常现象及其机理探讨

2013年7月22日甘肃岷县漳县M_s6.6地震后岷县申都乡某地窖出现冒白色烟雾的宏观异常现象。本文通过土壤气Rn、Hg现场检测和采样后气相色谱检测、生物显微镜观察结果,探讨了气体来源、赋存和运移机理以及异常形成的物理化学机制。认为该点具有灵敏的断层活动响应,可作为今后开展断层活动及未来甘东南地震趋势预测判定的断层土壤气监测点进行长期监测。     

Origin of the Yinshan epithermal-porphyry Cu–Au–Pb–Zn–Ag deposit,southeastern China: insights from geochemistry,Sr–Nd and zircon U–Pb–Hf–O isotopes

The Yinshan deposit is a large epithermal-porphyry polymetallic deposit, and the timing and petrogenesis of ore-hosting porphyries have been hotly debated. We present new results from geochemical, whole-rock Sr–Nd and zircon U–Pb–Hf–O isotopic investigations. Zircon U–Pb data demonstrate that the quartz porphyry, dacitic porphyry, and quartz dioritic porphyry formed at ?172.2 ± 0.4 Ma, ?171.7 ± 0.5 Ma, and ?170.9 ± 0.3 Ma, respectively. Inherited zircon cores show significant age spreads from ?730 to ?1390 Ma. Geochemically, they are high-K calc-alkaline or shoshonitic rocks with arc-like trace element patterns. They have similar whole-rock Nd and zircon Hf isotopic compositions, yet an increasing trend in ?_Nd(t) and ?_Hf(t) values typifies the suite. Older (inherited) zircons of the three porphyries display Hf compositions comparable to those of the Jiangnan Orogen basement rocks. In situ zircon oxygen isotopic analyses reveal that they have similar oxygen isotopic compositions, which are close to those of mantle zircons. Moreover, a decreasing trend of δ¹⁸O values is present. We propose that the ore-related porphyries of the Yinshan deposit were emplaced contemporaneously and derived from partial melting of Neoproterozoic arc-derived mafic (or ultra-mafic) rocks. Modelling suggests that the quartz porphyries, dacitic porphyries, and quartz dioritic porphyries experienced ?25%, ?10%, and ?10% crustal contaminations by Shuangqiaoshan rocks. Our study provides important constraints on mantle–crust interaction in the genesis of polymetallic mineralization associated with Mesozoic magmatism in southeastern China.     

Benthic foraminifera distribution in a tourist lagoon in Rio de Janeiro, Brazil: a response to anthropogenic impacts

Rodrigo de Freitas Lagoon, located in the Rio de Janeiro City, receives several types of polluted discharges. The knowledge of the sediment microfauna correlated with heavy metal and organic matter concentrations could supply important data about the conditions of the lagoon. The benthic foraminiferal assemblage presented larger diversity and more abundant samples in the lagoon entrance than in the inner area. The Ammonia tepida - Elphidiumexcavatum foraminiferal assemblage is characterized by dwarf, corroded and weak organisms. Agglutinated species were found only near the entrance. Low abundance values and sterility of five samples in the inner area (north/northeast) can be caused by high levels of heavy metals and organic matter. A. tepida shows negative correlation with increasing heavy metals values. PAHs and coprostanol high indexes, and the absence or low presence of microfauna in samples around the lagoon margin confirm illegal flows from gas stations and domestic sewage.     

大气环流模式（GCMs）在东南诸河流域的适用性评价

采用秩评分方法,选取NCEP再分析资料作为“实测”依据,以10个统计特征值为基础,评估了21个GCMs对东南诸河流域17个气候要素的模拟效果．结果显示：气候变量表现出不同的统计特征,GCMs对不同气候变量的模拟效果并不一致．与地面气象站点实测值对比,CSIRO：MK30、GFDL：CM21、GFDL：CM20、INM：CM30对降水和地面气温的模拟效果相对较好;流域高空气候要素的模拟效果更佳的模式有CGCM2．3．2、GISS：EH、BCCR：BCM20、GFDL：CM20对;综合所有气候变量,BCCR：BCM20、GFDL：CM20、CGCM2．3．2、GISS：EH的表现更优．优选出的GCMs可以为东南诸河流域气候变化的进一步研究提供科学依据．