New insights into the origin of perylene in geological samples   总被引：1，自引：0，他引：1  

Kliti Grice  Hong Lu  Pia Atahan  Muhammad Asif  Paul Greenwood  Ercin Maslen  Kenneth Williford 《Geochimica et cosmochimica acta》2009,73(21):6531-6543

The origin of the polycyclic aromatic hydrocarbon (PAH) perylene in sediments and petroleum has been a matter of continued debate. Reported to occur in Phanerozoic organic matter (OM), fossil crinoids and tropical termite mounds, its mechanism of formation remains unclear. While a combustion source can be excluded, structural similarities to perylene quinone-like components present in e.g. fungi, plants, crinoids and insects, potentially suggest a product-precursor relationship. Here, we report perylene concentrations, ¹³C/¹²C, and D/H ratios from a Holocene sediment profile from the Qingpu trench, Yangtze Delta region, China. Perylene concentrations differ from those of pyrogenic PAHs, and rise to prominence in a stratigraphic interval that was dominated by woody vegetation as determined by palynology including fungal spores. In this zone, perylene concentrations exhibit an inverse relationship to the lignin marker guaiacol, D/H ratios between −284‰ and −317‰, similar to the methoxy groups in lignin, as well as co-variation with spores from wood-degrading fungi. ¹³C/¹²C of perylene differs from that of land plant wax alkanes and falls in the fractionation range expected for saprophytic fungi that utilise lignin, which is isotopically lighter than cellulose and whole wood. During progressive lignin degradation, the relative carbon isotopic ratio of the perylene decreases. We therefore hypothesise a relationship of perylene to the activity of wood-degrading fungi. To support our hypothesis, we analysed a wide range of Phanerozoic sediments and oils, and found perylene to generally be present in subordinate amounts before the evolutionary rise of vascular plants, and to be generally absent from marine-sourced oils, few exceptions being attributed perhaps to a contribution of marine and/or terrestrial-derived fungi, anoxia (especially under marine conditions) and/or contamination of core material by fungi. A series of low-molecular-weight aromatic quinones bearing the perylene-backbone were detected in Devonian and Cretaceous sediments, potentially representing precursor components to perylene.  相似文献   

Distribution and significance of novel low molecular weight sterenes in an immature evaporitic sediment from the Jinxian Sag,North China     

Hong Lu  Tengshui Chen  Kliti Grice  Paul Greenwood  Ping’an Peng  Guoying Sheng 《Organic Geochemistry》2009,40(8):902-911

An unusual series of C₂₂–C₂₇ monounsaturated sterenes and C₂₄–C₃₀ tetracyclic terpanes (17,21-secohopanes) were detected in relatively high concentrations in an immature evaporitic marl sediment of the Jinxian Sag, Bohai Bay Basin, North China. The site of unsaturation in these novel sterenes is assigned tentatively to the D ring on the basis of mass spectral interpretation, which also distinguishes them from reported unsaturated sterenes. Other hydrocarbon biomarker or stable isotope characteristics are indicative of microbial (e.g. methyl hopanes), phytoplankton or higher plant (depleted δ¹³C values of isoprenoids and hopanes) inputs and an anoxic carbonate depositional environment (hexacyclic hopanes; tetracyclic terpanes). The hydrocarbon composition showed no obvious biodegradation and the relatively high concentration of unsaturated terpenoids (e.g. gammacerene) and low values of other established maturity parameters (T_s/T_m = 0.23; R_o = 0.44%; T_max = 417 °C), are consistent with sediments of low maturity. The novel, low molecular weight sterenes and the tetracyclic terpanes may be early diagenetic products of microbial sources in a carbonate environment.  相似文献   

黔西南白层超基性岩墙锆石SHRIMP U-Pb年龄和Hf同位素组成研究   总被引：14，自引：6，他引：8  

陈懋弘  章伟  杨宗喜  陆刚  侯可军  刘建辉 《矿床地质》2009,28(3):240-250

文章对黔西南白层地区出露的燕山期超基性岩墙进行了单颗粒锆石SHRIMP U-Pb年龄和Hf同位素组成研究,获得A、B两组不同的锆石年龄.A组锆石呈不规则粒状,具不完整的宽大条带,12颗锆石的 SHRIMP U-Pb年龄加权平均值为(84±1)Ma,代表了超基性岩墙的侵位年龄;锆石Hf原位分析表明,176Hf/177Hf从0.282561到0282719,εHf(84 Ma)平均为-3.61,表明岩浆源区主要以富集地幔为主,并受到部分地壳物质的混染.B组锆石晶形完整,具典型的中酸性岩浆型振荡环带,3颗锆石的SHRIMP U-Pb模式年龄为409～450 Ma.176Hf/177Hf从0282379到0282440,εHf(t)平均为-3.77,均低于A组锆石,属于捕获锆石.据此认为84 Ma左右由于华南岩石圈伸展,软流圈地幔上涌,导致岩石圈富集地幔部分熔融,熔体上升过程中与409～450 Ma左右形成的少量地壳岩石发生混染,随后快速侵位冷凝而形成基性-超基性岩墙.白层地区84 Ma的超基性岩浆活动是整个华南西部燕山晚期(80～90 Ma)岩浆活动的一部分.右江褶皱带周缘的燕山晚期岩浆活动主要与大规模的Sn、W、Ag、Cu、Pb、Zn等矿床有关,但右江褶皱带内部的燕山晚期岩浆活动是否与以卡林型金矿为代表的低温热液矿床有成因上的联系,尚需更多矿床年代学资料的证实.  相似文献   

Hydrogeochemistry of formation water in relation to overpressures and fluid flow in the Qikou Depression of the Bohaiwan basin,China     

Xuebin Du  Xinong Xie  Yongchao Lu  Liang Zhang  Cheng Zhang 《Journal of Geochemical Exploration》2009

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大庆长垣南部白垩纪断裂活动及对浅层气藏的控制   总被引：2，自引：0，他引：2       下载免费PDF全文

李建民  付晓飞  玄昌姬  陆延平  刘海涛 《地质科学》2009,44(2):513-524

大庆长垣南部包括葡北、敖包塔和葡两3个局部构造.黑帝庙油层的形成与3种不同演化历史断层有关：反转期断裂（Ⅲ犁）、断陷期形成坳陷期和反转期均活动的断裂（Ⅰ-Ⅱ-Ⅲ型）和坳陷期形成反转期活动的断裂（Ⅱ-Ⅲ型）;其中连通气源岩且活动期与大量生排气期相匹配的Ⅰ-Ⅱ-Ⅲ型和Ⅱ-Ⅲ型断裂是生物气垂向运移的主要通道,Ⅰ-Ⅱ-Ⅲ型断裂是深部CO₂向上运移的主要通道.这些断层均是“似花状”断层组合的边界断层,对倾边界断层控制背斜和鼻状构造形成.数值模拟表明：对倾的气源断层与地层产状的配置关系共同控制天然气运移方向和聚集的部位,由于葡萄花和敖包塔构造西缓东陡,因此天然气主要富集在背斜东翼和背斜之间的断块上.  相似文献   

松辽盆地朝阳沟阶地扶余-杨大城子油层油源分析与油气运移模式   总被引：2，自引：0，他引：2       下载免费PDF全文

张雷  卢双舫  王伟明 《地质科学》2009,44(2):560-570

基于生物标志化合物参数,系统对比分析了朝阳沟阶地扶余-杨大城子油层原油与三肇凹陷及朝阳沟阶地青山口组-段源岩的关系,表明朝阳沟阶地扶余油层有两个主要油源,即三肇凹陷青-段源岩与朝阳沟本地区青-段源岩,且两者对扶余油层的贡献量可能基本相同.朝阳沟地区杨大城子油层原油与三肇凹陷青-段源岩有密切的亲缘关系,与朝阳沟青-段源岩亲缘关系不明显.这与朝阳沟阶地源岩超压值相对较小、导致油气下排距离浅、进入杨大城子油层的油气量较小相符.在油源对比的基础上,结合断裂和砂体分布等各种地质条件,将朝阳沟阶地油气运移模式分为远源长距离侧向运移和近源短距离侧向运移两种类型.  相似文献   

Understanding the dynamical-microphysical-electrical processes associated with severe thunderstorms over the Beijing metropolitan region     

Xiushu QIE  Shanfeng YUAN  Zhixiong CHEN  Dongfeng WANG  Dongxia LIU  Mengyu SUN  Zhuling SUN  Abhay SRIVASTAVA  Hongbo ZHANG  Jingyu LU  Hui XIAO  Yongheng BI  Liang FENG  Ye TIAN  Yan XU  Rubin JIANG  Mingyuan LIU  Xian XIAO  Shu DUAN  Debin SU  Chengyun SUN  Wenjing XU  Yijun ZHANG  Gaopeng LU  Da-Lin ZHANG  Yan YIN  Ye YU 《中国科学:地球科学(英文版)》2021,64(1):10-26

The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.  相似文献   

基于平面波模型重访地震背景噪声互相关及空间自相关(SPAC)     

鲁来玉 《地球与行星物理论评》2021,(2)

自Aki(1957)提出微震的空间自相关(SPatial AutoCorelation,SPAC)技术以来,SPAC技术一直独立发展,并在工程地震领域获得了广泛应用.近20年来,地震干涉(Seisimic Interferometry,SI)在多个领域引起人们的关注,该技术的核心思想是连续地震背景噪声的互相关函数(Noise Crosscorrelation Function,NCF)可以重建系统的格林函数(Green's Function,GF),对该技术的回溯性研究建立了SPAC和NCF的关系:它们是对同一物理现象的不同描述,SPAC在频率域中描述随机平稳噪声的空间相干,NCF在时间域中描述扩散场的互相关.理论上SAPC和NCF技术要求背景噪声源均匀分布,这样的噪声场可以用平面波叠加来模拟.本文基于平面波模型重访地震背景噪声的互相关和空间自相关技术,从单色平面波的互相关表示出发,对地震背景噪声互相关及空间自相关技术进行评述,试图使这些概念更易于理解.与之前众多研究地震干涉技术的理论相比,本文尤其关注以下几点:(1)基于简单的平面波模型,给出不同维度下,源或台站对方位均匀分布时,平面波互相关对入射波的方位平均和台阵对的方位平均结果,并对格林函数GF和时域互相关函数NCF的关系进行总结.(2)给出声源和(或)交叉台站方位分布不均匀时的互相关表示,指出这种非均匀性对方位的依赖关系,与弱各向异性介质中面波速度的方位依赖关系类似,因此,非均匀源的影响在反演时可能会映射到面波方位各向异性结果中.(3)互相关运算中,哪一个台站是虚拟源.NCF包含因果性和非因果性两部分,NCF的非对称性通常用于研究噪声源的方位分布,但由于源和接收的互易关系,及对互相关运算的不同定义和不同的傅里叶变换习惯,哪一个台站是虚拟源在目前的文献中并不明确.(4)方位平均和时间平均的关系.在SPAC处理中,需要对不同方位分布的台站对进行方位平均,本文从理论上说明,单个平面波入射时,交叉台站互相关系数对台站对的方位平均,等价于单个台站对互相关系数对入射波的时间平均.(5)几种特定分布非均匀噪声源的SPAC表示.包括单独的因果性噪声源和非因果性噪声源给出的互相关函数表示,及由此带来的相移问题.(6)利用SPAC、NCF和面波GF之间的关系,给出交叉分量的空间自相关系数表示.(7)衰减介质的空间相干表示.虽然利用地震干涉技术研究介质衰减在理论上仍然存在一些争议,但人们正试图研究从连续背景噪声记录中提取介质衰减的可能性.本文基于平面波模型,给出了不同坐标选择下,衰减介质的空间相干表示,这种表达的不同,指示了由地震干涉技术提取介质衰减的困难.与众多研究地震干涉的理论相比,比如稳相近似理论、互易定理、时间反转声学等,本文主要考虑均匀介质,不涉及非均匀介质的散射,从最简单的平面波模型,理解背景噪声重建系统格林函数这一地震干涉的核心思想和相应的基本概念.  相似文献   

Assessment of global meteorological,hydrological and agricultural drought under future warming based on CMIP6          下载免费PDF全文

Jianxin Zeng  Jiaxian Li  Xingjie Lu  Zhongwang Wei  Wei Shangguan  Shupeng Zhang  Yongjiu Dai  Shulei Zhang 《大气和海洋科学快报》2022,15(1):49-55

在全球变暖背景下,分析和预测干旱的变化趋势和传播规律对于区域生态环境安全和灾害管理具有重要意义.本文基于第六次国际耦合模式比较计划(CMIP6),分析了SSP2-4.5和SSP5-8.5两种变暖情景下的气象(标准化降水指数SPI和标准化降水蒸发指数SPED,水文(标准化径流指数SRI)和农业(标准化土壤水分指数SSI)...  相似文献   

遥感图像空间分辨率改进值计算方法     

郭从洲  赖广陵  童晓冲  丁璐 《测绘科学技术学报》2017,34(1)

为了克服超分辨重建后的遥感图像空间分辨率的界定还采用人工对比判读存在误差和结论不统一的缺点,利用调制传递函数、奈奎斯特采样定理和人眼极限频率,建立了一种新的空间分辨率客观评价方法。利用该方法计算超分辨率重建后的遥感图像相比原始遥感图像空间分辨率的提高倍数,从而推断出重建后遥感图像的空间分辨率的大小。在数值测试中,利用不同的超分辨率方法对分级变频矩形光栅图像进行重建,采用提出的空间分辨率评价方法,与归一化均方误差、峰值信噪比、信息熵、灰度平均梯度进行客观评价的结果一致。此方法为遥感图像空间分辨率改进值的计算提供了一种可行的量化模型。  相似文献