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为评价新疆北部吉木乃坳陷页岩气勘探潜力,通过对吉木乃坳陷下二叠统卡拉岗组暗色页岩段有机地球化学以及储层特征分析,初步探讨其页岩气地质特征。卡拉岗组下段暗色页岩段烃源岩以碳质泥页岩为主,TOC最小值为0.3%,最大值为4.32%,平均值为1.01%。有机质丰度中等,有机质类型为Ⅲ型,Ro值介于1.43%~2.87%之间,平均值为2.12%。热演化程度为成熟-过成熟度阶段,具较好天然气生成能力。暗色页岩矿物成分以石英、长石等脆性矿物为主,粘土质矿物次之,具较好可裂性及吸附性。页岩孔隙以宏孔、细小孔以及小孔为主,储集空间主要为粒内及粒间溶孔、矿物间的微孔隙与微缝隙、矿物微裂缝。孔隙度为0.97%~1.52%,平均为1.36%。渗透率为0.0097~0.0197m D,平均为0.0139m D,具较好天然气储集能力。 相似文献
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青藏高原北部渐新统雅西措组湖相地层中的叠层石,具有典型的毫米级暗色富有机质纹层与浅色富碎屑纹层交替的生长节律,纹层形态呈穹窿状产出。为了探索湖湘叠层石纹层的成因和时间意义,我们采用激光微区采样技术分别对单个暗色纹层和浅色纹层进行了碳氧同位素分析。结果表明,每一个共轭纹层对中,暗色纹层相对于浅色纹层明显富集δ18O和δ13C,而且δ18O和δ13C之间具有正向变化关系,即δ18O和δ13C显示同步亏损和富集,反映季节性气候变化是影响纹层同位素信号周期性波动的主要因素,支持叠层石的对偶纹层为年纹层成因,它可以为气候和环境变化研究提供一种高分辨率地质材料。 相似文献
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北京石花洞石笋发育了典型的中国北方型石笋年层,年层层面具有双重光性[1],即在透光条件下表现为一阻光暗线,而在紫外光照射下表现为一发光亮线.研究表明,石笋年层层面的发光物质为有机质[2].通过洞穴观测,确认有机质(DOC)在雨季初期从土壤淋滤至石笋顶部沉积[3],而与之配合的是雨季碳酸钙沉积较少甚至不沉积[4],从而形成很薄的有机质发光条带.然而,石花洞石笋层面的发光亮线并不总是与阻光暗线位置重合,例如石笋TS9701,其发光亮线在两暗线之间也能单独出现[5],说明有机质(DOC)是透明的,并因此推测阻光物质(形成暗线)另有所属.曾经猜想暗色物质可能是粘土矿物,又因为粘土为含水硅酸盐矿物,所以我们曾经试图在雨季洞穴滴水中检出硅离子,但没有结果.高分辨高灵敏的原位分析仪器有可能解决这个疑问. 相似文献
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《中国煤炭地质》2015,(5)
基于钻孔岩心观察、室内试验测试以及结合前人研究成果,探讨了淮南煤田石炭-二叠系泥页岩层系分布特点及其沉积环境演化。结果表明:太原组、山西组和下石盒子组、上石盒子组均发育了不同厚度的泥页岩层系,泥岩岩石类型包括粉砂质泥岩、暗色泥岩和高岭石泥岩。太原组发育浅海相的碳酸盐岩和碎屑组成的含煤沉积,部分沼泽、湖泊相发育了泥岩;山西组为海退系列的水下三角洲平原沉积,下部厚约10m的暗色泥岩段有机质含量相对较高,为研究区内主要赋页岩气层段,上部为分流河道沉积,泥岩发育不稳定;下石盒子组与上石盒子组河流作用增强,沉积环境更靠近陆地一侧,不利于有机质的聚集,沉积泥岩有机质含量相对较低。山西组和下石盒子组为本区富有机质泥岩的富集层段,更具生气潜力。 相似文献
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内蒙古突泉盆地突D2井上二叠统林西组烃源岩新发现 总被引：3，自引：0，他引：3
在突泉盆地南部突D2井的钻探过程中发现厚层暗色泥岩中产Klausipollenites schaubergeri等19属26种具浓厚晚二叠世时代特征的孢粉化石.生物地层及岩石地层显示,这套暗色泥岩为上二叠统林西组,其单层厚度及总厚度大.本文从有机质丰度、类型、成熟度等方面分析了突D2井暗色泥岩的生烃潜力.有机质丰度为中等-好.有机质类型为Ⅱ1型.有机质成熟度为过成熟.显示突泉盆地林西组暗色泥岩具有良好的页岩气勘探前景. 相似文献
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四川盆地中部侏罗系大安寨段含有机质泥质介壳灰岩储层的认识及其意义 总被引：1，自引：0，他引：1
四川盆地中部下侏罗统大安寨段可划分为三个亚段,主要由暗色泥页岩、结晶介壳灰岩、泥质介壳灰岩三种岩性构成。暗色泥页岩形成于深湖—半深湖相环境,是主要的烃源岩,滨浅湖高能滩相结晶介壳灰岩一向被认为是主要储层,其储集空间以裂缝为主。露头地质调查、岩心和薄片观察、物性资料及试油资料的分析表明,浅湖—半深湖较低能滩相含有机质泥质介壳灰岩是主要的储集层和产层,单层厚度薄,但累积厚度较大,分布面积广,常夹于暗色泥页岩中,源储一体,更有利于成藏。这类泥质介壳灰岩的壳间孔构成了主要的储集空间,壳间孔平行于壳体的长轴方向排列,并常见黑色有机质充填。认为四川盆地大安寨段的油气勘探方向可由结晶介壳灰岩向含有机质的泥质介壳灰岩拓展,浅湖—半深湖较低能滩沉积相带可成为新的勘探领域。初步预测大安寨段上部的一亚段新增有利勘探面积6 100 km2,中部的一三亚段新增有利勘探面积6 600 km2。 相似文献
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鄂西地区陡山沱组页岩气成藏地质条件研究 总被引：2，自引：0，他引：2
在野外地质露头观察的基础上,通过地球化学分析测试、扫描电镜、X-衍射、低温氮气吸附、等温吸附等分析测试,对鄂西地区陡山沱组暗色泥页岩的发育分布、有机地球化学特征、储层特征及吸附性能等页岩气成藏地质条件进行了研究。结果表明,研究区陡山沱组发育厚层暗色泥页岩,且区域分布稳定,具有有机质丰度较高,有机质类型好,热演化程度高,脆性矿物丰富,物性良好,储层孔隙空间发育,吸附性能好等特点,且具有较好的保存条件,具备页岩气聚集成藏的有利地质条件。通过综合信息叠合法,认为鄂西地区黄陵背斜南翼及长阳背斜地区为页岩气勘探有利区带,陡山沱组陡二段中下段为页岩气勘探有利目的层段。 相似文献
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南祁连盆地木里凹陷侏罗系发育多层暗色泥岩,从有机质丰度?有机质类型?有机质成熟度等3 方面对DK-3井烃源岩进行评价表明,其有机质丰度相对较高,有机质类型为Ⅱ1(腐殖-腐泥型)~Ⅱ2(腐泥-腐殖型)型,烃源岩整体处于成熟热演化阶段;烃源岩生烃潜力最高的层段为深度140~350 m内的黑色湖相泥岩,其有机质丰度高,类型好,且已达到成熟阶段;其次为深度630~720 m内的灰色泥岩夹层;其他层段烃源岩有机质丰度整体偏低,生烃潜力有限? 相似文献
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洞穴碳酸盐微层研究及其发展方向 总被引：4，自引：0，他引：4
近几年,在分辨率气候－环境变化研究中,洞穴碳酸盐微层逐渐受到人们重视。洞穴碳酸盐微层的类型较多,主要为年层。微层是在沉积条件发生高频率的周期性改变时形成的,要受到供水条件和碳酸钙浓度等多因素的控制。洞穴碳酸盐微层的稳定同位素组成,生长速率,微层结构与物质组分,微层厚度与灰度和光学特征等可以反映降水,温度,土壤成分及植被变化等信息。 相似文献
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《Quaternary Science Reviews》2003,22(5-7):555-567
Petrographical and geochemical parameters of stalagmites from the B7 cave in Iserlohn–Letmathe (Northern Rhenish Massif, NW Germany) record Late- and postglacial climate changes (temperature and/or precipitation). Fabrics and microfacies of the stalagmite profiles lead to a differentiation of four hierarchies of rhythms. Clastic layers in the stalagmites are caused by flooding events and are time markers. Twenty-four TIMS Th/U-age-dates provide a time calibration of stalagmite growth phases. One stalagmite reveals an early growth period between 17.6 and 16.7 ka BP. Between 9.6 and 5.5 ka BP (Atlantic episode of the Holocene) the growth rate of the stalagmites was higher than before and after this time, with dominant light-porous microfacial laminae and high δ18O and δ13C values representing partly kinetic fractionation effects. This part of the Holocene is interpreted as a mainly warm episode with frequent interruptions of dripping. Within the past 4 ka the profiles with predominant dark compact facies reveal low isotopic values which may be interpreted as a temperature proxy record. The stalagmite records resemble records from an Irish stalagmite. Correlation with the Δ14C record from European tree rings suggests that colder periods in the North Atlantic were accompanied by drier winters in central Europe. 相似文献
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Mauro Cremaschi 《Geoarchaeology》1996,11(5):393-421
The manganese-rich rock varnish from the Messak Settafet plateau is a relict feature that developed at the end of the Holocene humid cycle, before the onset of the present-day hyperarid conditions. The Messak Settafet varnish consists of three microlayers of different composition and micromorphological features. The innermost microlayer is composed of illuvial clay. The second, middle microlayer is the classic manganese-rich rock varnish. The outermost microlayer is composed of unaltered aeolian dust. Each microlayer formed under different climatic conditions, and the microstratigraphy records a climatic evolution from a wet environment towards progressive desertification. The relationship between desert varnish, rock engravings, and radiocarbon-dated archaeological evidence and the comparison with the Holocene climatic evolution as from cave deposits suggest that most of the varnish developed since the end of the VI millennium B.P. under a semiarid climate characterized by steppe-type vegetation, up to the onset of desert conditions, during the IV millennium B.P. © 1996 John Wiley & Sons, Inc. 相似文献
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We have measured δ44/42Ca of laboratory-precipitated calcite grown in an experimental setup that closely replicates stalagmite formation. Calcium solutions were dripped onto two different substrates in tightly-controlled conditions and calcite precipitated due to rapid CO2 degassing. With seeded glass slides as the substrate, we observe a Ca isotope ratio in the calcite which is ∼0.5‰ per amu lower than that in the growth solution. This fractionation is generally almost twice that observed in previously published calcite growth experiments and indicates a large kinetic effect on Ca isotopes in the stalagmite growth environment. The precipitate forming near the spot where the drip lands shows slightly greater solution-to-precipitate fractionation than calcite further from the drip reflecting a decrease in this kinetic fractionation as precipitation continues. We interpret these results in the context of the model of Fantle and DePaolo (2007) which involves surface entrapment of light Ca isotopes to decrease calcite δ44/42Ca, and depletion of Ca from the solution in the direct vicinity of the growing calcite to increase calcite δ44/42Ca. In the stalagmite setting, the second of these effects is minimized so that calcite Ca isotope ratios are unusually light. This interpretation suggests that stalagmite Ca isotope ratios should decrease with the saturation state of the drip water (i.e. with the growth rate of calcite). Ca isotopes might therefore allow reconstruction of surface entrapment of trace metals and isotopes more generally and might, for instance, allow an assessment of the appropriate relationship between oxygen isotope fractionation and temperature for periods of past growth in stalagmites. 相似文献
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Daniel Schimpf Rolf Kilian Andreas Kronz Klaus Simon Christoph Spötl Gerhard Wörner Michael Deininger Augusto Mangini 《Quaternary Science Reviews》2011,30(3-4):443-459
Stalagmites are important palaeo-climatic archives since their chemical and isotopic signatures have the potential to record high-resolution changes in temperature and precipitation over thousands of years. We present three U/Th-dated records of stalagmites (MA1–MA3) in the superhumid southern Andes, Chile (53°S). They grew simultaneously during the last five thousand years (ka BP) in a cave that developed in schist and granodiorite. Major and trace elements as well as the C and O isotope compositions of the stalagmites were analysed at high spatial and temporal resolution as proxies for palaeo-temperature and palaeo-precipitation. Calibrations are based on data from five years of monitoring the climate and hydrology inside and outside the cave and on data from 100 years of regional weather station records.Water-insoluble elements such as Y and HREE in the stalagmites indicate the amount of incorporated siliciclastic detritus. Monitoring shows that the quantity of detritus is controlled by the drip water rate once a threshold level has been exceeded. In general, drip rate variations of the stalagmites depend on the amount of rainfall. However, different drip-water pathways above each drip location gave rise to individual drip rate levels. Only one of the three stalagmites (MA1) had sufficiently high drip rates to record detrital proxies over its complete length. Carbonate-compatible element contents (e.g. U, Sr, Mg), which were measured up to sub-annual resolution, document changes in meteoric precipitation and related drip-water dilution. In addition, these soluble elements are controlled by leaching during weathering of the host rock and soils depending on the pH of acidic pore waters in the peaty soils of the cave’s catchment area. In general, higher rainfall resulted in a lower concentration of these elements and vice versa. The Mg/Ca record of stalagmite MA1 was calibrated against meteoric precipitation records for the last 100 years from two regional weather stations. Carbonate-compatible soluble elements show similar patterns in the three stalagmites with generally high values when drip rates and detrital tracers were low and vice versa. δ13C and δ18O values are highly correlated in each stalagmite suggesting a predominantly drip rate dependent kinetic control by evaporation and/or outgassing. Only C and O isotopes from stalagmite MA1 that received the highest drip rates show a good correlation between detrital proxy elements and carbonate-compatible elements. A temperature-related change in rainwater isotope values modified the MA1 record during the Little Ice Age (～0.7–0.1 ka BP) that was ～1.5 °C colder than today. The isotopic composition of the stalagmites MA2 and MA3 that formed at lower drip rates shows a poor correlation with stalagmite MA1 and all other chemical proxies of MA1. ‘Hendy tests’ indicate that the degassing-controlled isotope fractionation of MA2 and MA3 had already started at the cave roof, especially when drip rates were low. Changing pathways and residence times of the seepage water caused a non-climatically controlled isotope fractionation, which may be generally important in ventilated caves during phases of low drip rates. Our proxies indicate that the Neoglacial cold phases from ～3.5 to 2.5 and from ～0.7 to 0.1 ka BP were characterised by 30% lower precipitation compared with the Medieval Warm Period from 1.2 to 0.8 ka BP, which was extremely humid in this region. 相似文献
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High resolution carbon isotopic records in millennial, centennial and decadal timescales from three stalagmites from three different caves under a similar monsoon climate in Guangxi–Guizhou, China, provided detailed information on the paleo-ecological environmental conditions in the past 15,000 years. The results indicate that during the glacial period, or cold-dry period, such as Heinrich event H1 and Younger Dryas event karst development was poor as was pedogenesis, C3 vegetation didn’t grow well, resulting in C4 plants dominating and with heavy δ13C values in stalagmites. In a warm-humid stage, C3 vegetation grew well and predominated with negative δ13C values. The δ13C records from stalagmites could be indicative of sensitive vegetation changes and reflective of climate changes in precipitation, temperature, etc. The δ13C records may also be used to distinguish different effects from nature or human activity. Particularly since the late Holocene, human activities have increased disturbances to environment, even more than natural factors. Forest vegetation was destroyed, C4 plants became dominant, and rock desertification was aggravated because of severe water and soil loss, all resulting in sharply increasing δ13C values of stalagmites that are heavier than pre-middle Holocene δ13C values. 相似文献
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Large variations of δ13C values in stalagmites from southeastern China during historical times: implications for anthropogenic deforestation 
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下载免费PDF全文 Haiwei Zhang Yanjun Cai Liangcheng Tan Hai Cheng Shijiang Qin Zhisheng An R. Lawrence Edwards Le Ma 《Boreas: An International Journal of Quaternary Research》2015,44(3):511-525
Variations in speleothem δ13C values can reflect changes in overlying surface vegetation, which, over historical time scales, may represent the influence of human activities. Here, we examined δ13C variations in two stalagmites growing for the last 2200 years in Shennong Cave, Jiangxi Province, SE China. The two δ13C records corroborate well one another and show a prominent 6‰ enrichment of the δ13C values from AD 700 to 1100. The isotopic equilibrium for modern calcite and negative correlation between δ18O and δ13C values along the growth axis suggest that the influences of kinetic fractionation are negligible. Varied correlations between Mg/Ca and Sr/Ca ratios and divergent changes between δ13C values and Mg/Ca and Sr/Ca ratios from AD 700 to 1100 reveal that the prior calcite precipitation (PCP) and water–rock interaction did not dominate the increase of δ13C values. It is plausible that the obvious δ13C variation was largely influenced by the changes in vegetation cover overlying the cave. Our δ13C results, together with the records of climate and human activity from historical documentary records, suggest that: (i) prior to AD 700, small fluctuations in relatively light δ13C values reflect the presence of lush forest coverage above the cave, which was minimally disturbed by human activities; (ii) during AD 700–1100, the drastic increase in δ13C values indicates persistent and massive deforestation associated with large‐scale immigration into northern Jiangxi after the Rebellion of An & Shi (AD 755–763) in the Tang Dynasty and the subsequent development of agriculture and economic activity; and (iii) since AD 1100, fluctuations in relatively high δ13C values suggest that local vegetation during the last millennium has been sparse. Since the Rebellion of An & Shi, southeastern China was progressively developed, coincident with deforestation and vegetation deterioration caused by human disturbance in the form of deforestation and cultivation. 相似文献
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The analysis of organic matter (OM) preserved in stalagmites is a growing field, but there have been few studies of biomarker compounds such as lignin phenols that are widely used in other palaeoenvironmental contexts. Here we present a preliminary qualitative study of the OM in six stalagmite samples from contrasting environments, using thermochemolysis in the presence of tetramethylammonium hydroxide (TMAH). The results indicate that a wide variety of products is preserved, including several potential lignin-derived compounds, but also that further research is needed to maximise compound recovery and allow the analysis of dissolved OM preserved in stalagmites to reach its full potential. 相似文献
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Proxy records from speleothems are used in palaeoclimatic reconstructions, as the factors controlling their growth rate, nature of their internal structure and chemical composition respond to changes in surface climate. Optical analyses of stalagmites include visual observation of stalagmite images obtained from flatbed scanners or digital cameras. Hyperspectral imaging has not been used in stalagmite research, but potentially has many advantages over standard optical imaging techniques. Hyperspectral images of a set of stalagmites have been obtained in order to demonstrate the application of hyperspectral imaging in speleothem research. Our results highlight the following: (1) Spectra obtained for these calcite stalagmites are similar between a group of stalagmites of different ages, hydrological setting within a cave and from different caves. (2) The largest differences in relative reflectance between areas of dark compact calcite (DCC) and white porous calcite (WPC) are in the range 470–590 nm (this may extend to 680 nm for some of the stalagmites). (3) Imaging in the near infrared (NIR) demonstrates a decrease in reflection at water absorbance wavelengths, suggesting there is potential for mapping H2O. 相似文献