东海陆架盆地伸展率和压缩率及构造跃迁

东海陆架盆地位于欧亚板块的东南缘和西太平洋活动大陆边缘,本文选取了东海陆架盆地主要凹陷的17条地震剖面,采用平衡剖面技术,计算了主要凹陷新生代不同演化阶段的伸展率和压缩率。分析表明,东海陆架盆地构造演化总体由西向东跃迁。晚白垩世至晚古新世东海陆架盆地裂陷中心在西部坳陷带,始新世东迁至东部坳陷带,上新世东迁至东海陆架盆地东侧的冲绳海槽盆地。古新世中后期东海陆架盆地西部坳陷带北侧昆山凹陷反转; 中新世东部坳陷带的西湖凹陷反转。东海陆架盆地西部坳陷带与东部坳陷带构造演化不同,证明了东海陆架盆地的东西分带。西部坳陷带北部的长江坳陷和南部的台北坳陷构造演化不同,东部坳陷带北部的西湖凹陷和南部的钓北凹陷构造演化不同,证明了东海陆架盆地的南北分块.     

冀东金宝沟花岗斑岩地球化学特征、LA-ICP-MS锆石U-Pb年龄和Hf同位素及其地质意义

金宝沟金矿床是冀东地区近年查明的一个大型斑岩型金矿床,金矿体主要赋存于金宝沟花岗斑岩体及岩体与太古宙迁西群黑云角闪斜长片麻岩接触带中。为查明金宝沟含矿花岗斑岩体的成岩时代、岩石地球化学特征、岩浆源区特征及其与区域上峪耳崖、牛心山等成矿花岗岩体的关系,采用LA-ICP-MS锆石U-Pb定年方法,测得金宝沟2件花岗斑岩的成岩年龄分别为169.9±1.0Ma和170.4±2.0Ma,表明其形成于中侏罗世。金宝沟花岗斑岩属于过铝质钾玄岩系列岩石,∑REE含量为38.17×10~(-6)~136.51×10~(-6),岩石富集Rb、K等大离子亲石元素和Ba、Th、U,亏损Ta、Nb、Ti等高场强元素和P、Sr,显示出典型岛弧或活动大陆边缘岩浆岩的特征。锆石Hf同位素研究显示,2件花岗斑岩样品的锆石ε_(Hf)(t)分别为-12.8~-7.4和-14.4~-8.8,两阶段模式年龄分别为1685~2028Ma和1773~2130Ma,暗示岩浆可能来源于古元古代地壳物质的部分熔融。金宝沟花岗斑岩岩浆形成的温度为788~834℃,岩浆形成压力为0.8~1.6GPa。结合区域地质资料认为,包括金宝沟花岗斑岩在内的冀东中侏罗世花岗岩及同时代的髫髻山组火山岩是在陆内收缩、地壳增厚、古太平洋板块向欧亚大陆俯冲的构造背景下,在挤压应力松弛的间隙环境侵位的。     

全球过去千年典型暖期温度空间格局重建

利用过去两千年全球变化研究网络(PAGES 2k network)最新公布的501条代用记录, 重建了全球过去千年全年平均温度空间格局的演化特征, 对比分析了中世纪暖期及其最暖100年与20世纪现代暖期、中世纪暖期和小冰期最暖30年与20世纪最近30年的年平均温度空间模态异同。结果显示, 在世纪尺度上, 现代暖期与历史上中世纪暖期的温度异常空间格局大致相同, 变化幅度也在大部分区域相当, 但从年代际尺度上, 最近30年的升温比过去千年中世纪暖期和小冰期两个典型时期都明显。值得一提的是北大西洋中高纬度海温变化与上述特征并不相同, 在年代际和世纪尺度上小冰期和中世纪暖期海温均高于20世纪。可能原因是大西洋经圈翻转环流在中世纪暖期、 小冰期和20世纪现代暖期等3个特征时段对太阳辐射、火山活动和温室气体等外强迫的响应不同。     

煤矸石合成莫来石熟料研究

研究了煤矸石加氢氧化铝及氧化铝合成莫来石熟料的可行性。实验表明,采用煤矸石和氢氧化铝可在１５００℃完成莫来石化反应,到１５５０℃可得到接近理论密度的莫来石熟料,采用煤矸石和工业氧化铝反应,可在１５５０℃全部合成莫来石,到１６００℃可得到接近理论密度的莫来石熟料,采用煤矸石加α－Ａｌ２Ｏ３所得样品性能良好,化学成分最纯。     

Corn Area Extraction by the Integration of MODIS-EVI Time Series Data and China’s Environment Satellite (HJ-1) Data

In this paper, we intent to use the remotely sensed MODerate resolution Imaging Spectroradiometer (MODIS) data and China’s Environment Satellite (HJ-1) data for extracting the corn cultivated area over a regional scale. The high resolution HJ-1 data was to extract corn distribution at a small scale class with Support Vector Machine (SVM). The mean Enhanced Vegetation Index (EVI) time series curve of corn from MODIS was derived for the reference area and validated in a larger area. The MODIS-EVI time series curve derived from the reference area instead of the MODIS-EVI time series curve derived from the study area after validation, which was taken as the standard MODIS-EVI time series curve in for generating a standard MODIS-EVI image of corn. The mean absolute distance (MAD) between the standard MODIS-EVI image of corn and the MODIS-EVI time series image was used to detect the maximum possible extent of corn distribution in the study area. The results showed that the overall accuracy of the method was 82.17 %, with commission and omission errors of 16.85 and 15.40 %, respectively; at the county level, the satellite-estimated corn area and statistical data were well correlated (R ²?=?0.85, N?=?50) for the whole Jilin Province. It indicated that the MODIS data integrated with higher spatial resolution of HJ-1 satellite data could be utilized to enhance the extraction accuracy of corn cultivated area at a larger scale.     

Ensemble standardization constraints on the influence of the tree growth trends in dendroclimatology

Climate Dynamics - Tree growth trends can affect the interpretation of the response of tree-ring proxies (especially tree-ring width) to climate in the low-frequency band, which in turn may limit...     

Temporal and spatial variations in the discharge and dissolved organic carbon of drip waters in Beijing Shihua Cave,China

To detect the causal relationship between cave drip waters and stalagmite laminae, which have been used as a climate change proxy, three drip sites in Beijing Shihua Cave were monitored for discharge and dissolved organic carbon (DOC). Drip discharges and DOC were determined at 0 to 14‐day intervals over the period 2004–2006. Drip discharges show two types of response to surface precipitation variations: (1) a rapid response; and (2) a time‐lagged response. Intra‐annual variability in drip discharge is significantly higher than inter‐annual variability. The content of DOC in all drip waters varies inter‐ and intra‐annually and has good correlation with drip water discharge at the rapid response sites. High DOC was observed in July and August in the three years observed. The flushing of soil organic matter is dependent upon the intensity of rain events. The DOC content of drip water increases sharply above a threshold rainfall intensity (>50 mm d^?1) and shows several pulses corresponding with intense rain events (>25 mm d^?1). The DOC content was lower and less variable during the dry period than during the rainy period. The shape of DOC peak also varies from year to year as it is influenced by the intensity and frequency of rainfall. The different drip sites show marked differences in DOC response, which are dominated by hydrological behaviour linked to the recharge of the soil and karst micro‐fissure/porosity network. The results explain why not all stalagmite laminae are consistent with climate changes and suggest that the structure of the rainy season events could be preserved in speleothems. Copyright © 2008 John Wiley & Sons, Ltd.