三维地震资料在圈定煤层结构变化上的应用

随着煤炭开采机械化程度的不断提高,煤层结构的变化对采掘工作的影响日益突出。三维地震资料不仅能够控制落差3~5m以上的断层和幅度大于5m的褶曲,而且还可以利用三维资料所包含的丰富地质信息,包括煤层反射波振幅能量强弱的变化、波阻抗反演等对煤层结构的变化情况进行圈定,以提供煤层结构方面的地质资料。     

Late second-early first millennium BC abrupt climate changes in coastal Syria and their possible significance for the history of the Eastern Mediterranean

The alluvial deposits near Gibala-Tell Tweini provide a unique record of environmental history and food availability estimates covering the Late Bronze Age and the Early Iron Age. The refined pollen-derived climatic proxy suggests that drier climatic conditions occurred in the Mediterranean belt of Syria from the late 13th/early 12th centuries BC to the 9th century BC. This period corresponds with the time frame of the Late Bronze Age collapse and the subsequent Dark Age. The abrupt climate change at the end of the Late Bronze Age caused region-wide crop failures, leading towards socio-economic crises and unsustainability, forcing regional habitat-tracking. Archaeological data show that the first conflagration of Gibala occurred simultaneously with the destruction of the capital city Ugarit currently dated between 1194 and 1175 BC. Gibala redeveloped shortly after this destruction, with large-scale urbanization visible in two main architectural phases during the Early Iron Age I. The later Iron Age I city was destroyed during a second conflagration, which is radiocarbon-dated at circa 2950 cal yr BP. The data from Gibala-Tell Tweini provide evidence in support of the drought hypothesis as a triggering factor behind the Late Bronze Age collapse in the Eastern Mediterranean.     

Palynological records of Holocene monsoon change from the Gulf of Tonkin (Beibuwan), northwestern South China Sea

Palynological records in cores C4 and B106 from the Gulf of Tonkin reveal signals of paleo-monsoon and paleoenvironmental change during the late Pleistocene and Holocene. Before ∼ 13.4 cal kyr BP, the Gulf of Tonkin was exposed to the atmosphere and covered by grassland. Starting at ∼ 11.7 cal kyr BP, the Gulf of Tonkin was inundated by brackish water, indicated by the appearance of the brackish algae Cleistosphaeridium, Sentusidinium and Spiniferites, a decrease of herb content, and an increase of Pinus. After Hainan Island was completely separated from the Leizhou Peninsula by Qiongzhou Strait at ∼ 8.5 cal kyr BP, a continuous marine sedimentary environment was found. The current patterns were similar to those of the present, with a general trend of current homogenization reflected by gradually decreasing quantities of Quercus pollen and a narrowing gap between the palynological concentrations of the southern and northern parts of the region. The data suggest that three short periods of strengthened winter monsoons and currents were centered at ∼ 6.0 cal kyr BP, ∼ 2.7 cal kyr BP and ∼ 0.2 cal kyr BP and that two short periods of strengthened summer monsoons and currents were centered at ∼ 7.5 cal kyr BP and ∼ 3.4 cal kyr BP.     

Paleofire reconstruction for high-elevation forests in the Sierra Nevada, California, with implications for wildfire synchrony and climate variability in the late Holocene

Here, we present two high-resolution records of macroscopic charcoal from high-elevation lake sites in the Sierra Nevada, California, and evaluate the synchroneity of fire response for east- and west-side subalpine forests during the past 9200 yr. Charcoal influx was low between 11,200 and 8000 cal yr BP when vegetation consisted of sparse Pinus-dominated forest and montane chaparral shrubs. High charcoal influx after ∼ 8000 cal yr BP marks the arrival of Tsuga mertensiana and Abies magnifica, and a higher-than-present treeline that persisted into the mid-Holocene. Coeval decreases in fire episode frequency coincide with neoglacial advances and lower treeline in the Sierra Nevada after 3800 cal yr BP. Independent fire response occurs between 9200 and 5000 cal yr BP, and significant synchrony at 100- to 1000-yr timescales emerges between 5000 cal yr BP and the present, especially during the last 2500 yr. Indistinguishable fire-return interval distributions and synchronous fires show that climatic control of fire became increasingly important during the late Holocene. Fires after 1200 cal yr BP are often synchronous and corroborate with inferred droughts. Holocene fire activity in the high Sierra Nevada is driven by changes in climate linked to insolation and appears to be sensitive to the dynamics of the El Niño-Southern Oscillation.     

Palynological evidence for Pennsylvanian (Late Carboniferous) vegetation change in the Sydney Coalfield,eastern Canada

The palynology of clastic samples from seven stratigraphical levels in the late Moscovian Sydney Mines Formation, exposed along the shore at Bras d'Or, Nova Scotia, has been investigated. Most of the samples were from roof shales of major coals; the one sample that was not yielded a much higher proportion of pollen derived from extra‐basinal vegetation. The four stratigraphically lower roof shale samples yielded essentially similar palynological spectra, with 39 ± 4% lycophytes, 9 ± 4% sphenophylls, 23 ± 4% tree‐ferns, 12 ± 4% other ferns and 5 ± 3% cordaites. The palynology of the upper part of the investigated succession suggests a shift in vegetation towards one favouring more marattialean tree‐ferns, cordaites and conifers, and fewer lycophytes. This correlates with changes in drainage patterns as the alluvial plain migrated seawards and thus changed water tables. No evidence was found to suggest significant climate change at this time. Copyright © 2009 John Wiley & Sons, Ltd.     

内蒙古中西部钼多金属矿床地质特征及其动力学背景

本文首次对内蒙古中西部白乃庙铜-钼-金矿床、大苏计钼矿床、西沙德盖钼矿床、柳坝沟金-钼矿床、哈达门沟金-钼矿床、查干花钼-钨矿床和流沙山钼-金矿床的产出环境、地质特征、成因类型和时空分布特点进行了简要总结,对成矿作用与构造-岩浆活动的关系进行了概略性论述。柳坝沟、哈达门沟和白乃庙矿床均在前寒武纪变质岩地层中产出,大苏计、查干花、西沙德盖和流沙山矿床直接产于海西-印支期中酸性侵入岩中,尽管上述矿床在产出环境和地理位置上存在有一定差别,但是它们均与花岗岩类侵入岩体(或岩脉)具有密切的空间分布关系,属与中酸性侵入岩有关的钼多金属矿床。另外,根据矿床(点)的空间分布特点,可划分出5个钼多金属矿化集中区:即大苏计-明星沟钼矿化集中区、白乃庙-谷那乌苏铜-钼-金矿化集中区、哈达门沟-沙德盖金-钼矿化集中区、马尼图-查干花钼-铋-钨矿化集中区和流沙山-黑鹰山钼-金-铁矿化集中区。研究结果表明,成矿作用与板块消减、碰撞和缝合过程中所诱发的构造-岩浆事件密切相关,是地壳特定演化阶段构造-岩浆活动的产物。     

1948-2009年塔里木盆地空中水汽输送时空分布特征

利用1948-2009年美国NCEP/NCAR的逐月再分析资料(2.5°×2.5°),分析了塔里木地区大气中不同层次水平和垂直方向的水汽输入、输出和收支情况及其变化趋势.结果表明:1)塔里木盆地上空水平方向为水汽汇,且纬向贡献大于经向,垂直方向水汽主要由下层向中上层输送;2)水汽的水平和垂直净收支均具有季节性变化,且夏季辐合为主,冬季辐散为主;3)水汽的水平和垂直输送都表现为较一致的年际变化,且均在1970年代中后期出现了较明显的年代际突变;4)在1978年到2003年全球变暖明显的时段内,水平方向水汽净输入量呈减少趋势,垂直方向呈增加趋势.可以认为,在气候变化背景下,全球变暖加速了水循环,但同时改变了纬向的热力差异,导致塔里木盆地局地水循环的加速,以及经向水汽净输入量的减少.     

塔里木河流域适应气候变化和人类活动的应对措施

自2001年开始实施塔里木河流域近期综合治理工程,提出了以强化流域水资源统一管理和调度为核心,以源流区节水改造和干流河道治理为重点进行综合治理,积极稳妥地进行经济结构调整,实施退耕封育保护,有效保护好现有天然林草植被.通过向塔里木河下游生态输水,干涸近30a的台特玛湖于2001年11月16日开始有水,使塔里木河下游绿色走廊得到初步复苏等,流域生态环境得到极大的恢复.然而,自2007年以来,塔里木河向下游输水已大为减少,仅能输水到中游,特别是2009年水文干旱,塔里木河干流断流达1 100km多,使下游绿色走廊再度陷入生态危机.为此,需要重新审视塔里木河流域的综合治理,从加强源流治理开始,来巩固干流治理成果.认真总结10a来治理经验与教训,针对人类活动和气候变化对源流与干流造成的影响程度,积极采取应对措施.     

青海湖北岸土壤温度变化特征

利用1981-2008年刚察站0～320cm逐月平均土壤温度资料和2001-2008年逐日土壤温度观测资料,分析了青海湖北岸土壤温度变化特征、气候突变和异常年份.结果表明:各层年、季平均土壤温度呈现为极显著的升高趋势,升温率为0.25～0.91℃.(10a)-1;月平均土壤温度呈波形变化,位相随深度增加而滞后;日平均土壤温度呈正弦曲线变化;1月和10月随着深度的增加,土壤温度逐渐增大,4月和7月土壤温度随深度增加而减小;14:00时土壤温度随着深度增加逐渐下降,2:00时、8:00时和20:00时土壤温度随着深度增加而升高;除冬季5cm和15cm,秋季40cm平均土壤温度变化相对平稳,未出现突变现象外,其余各层年、季平均土壤温度均发生了突变;15cm、20cm、40cm、160cm和320cm年平均土壤温度均在20世纪80年代出现了异常偏冷,春季平均土壤温度出现了异常偏暖现象,其余各季和年平均地均表现为异常偏冷.     

气候变化对地表水环境的影响研究与展望

全球气候变暖引起水资源量和时空上的分布变化,进一步将影响着地表水环境,改变着河流湖泊的水质和环境情势.大多数关于气候变化对水的影响研究主要集中在气候变化对水量的影响方面,对水环境影响方面的定量研究相对较少.基于目前关于气候变化和水环境国内外现有的研究成果,本文主要讨论了气候变化(温度和极端水文事件)对河道、湖泊等水体水质的带来的可能影响,总结了目前的一些研究和采用的方法主要包括经验统计和模型模拟.在此基础上,提出了气候变化和水环境影响研究方面的展望.