四川盆地上震旦统灯影组风化壳古岩溶特征及模式分析

风化壳古岩溶的发育是四川盆地上震旦统灯影组获得新突破的重要因素。基于大量野外剖面、钻井岩心及薄片观察、地震、测井及地球化学分析,在论证灯影组两套风化壳古岩溶发育的基础上,进行古岩溶相带特征研究及差异分析,进而建立相应的风化壳古岩溶发育模式。结果表明,灯影组两套风化壳古岩溶均符合缓坡模式,但受古地貌坡降差异的影响,灯四段不整合面附近岩溶作用强烈,发育大洞穴及角砾、泥岩充填物,垂向分带结构以水平潜流带和深部缓流带为主;灯二段不整合面附近岩溶作用相对和缓,溶洞充填物主要由小粒径的角砾云岩、白云岩组成,盆地范围内其垂向分带结构以垂向渗流带、水平潜流带及深部缓流带为主。     

鄂尔多斯盆地马家沟组风化壳气层特征分析

为了对鄂尔多斯盆地奥陶系马家沟组风化壳气藏进行有效的岩性识别和气层识别,通过岩心描述、薄片观察、物性测试及测井分析等手段,结合试气成果,明确了风化壳储层的岩石学特征、孔隙结构特征以及电性和含气性特征,并在此基础上建立了岩性和气层解释标准。研究认为:含膏白云岩是盆地中东部风化壳主要储层类型,膏模孔是主要储集空间;储层低孔低渗,溶孔发育的非均质性加剧了储层非均质性;密度-深侧向电阻率交会图版可以很好地区分灰岩和白云岩,声波时差-深侧向电阻率交会图版也有较好的识别效果;应用声波时差-深侧向电阻率交会图版和密度-深侧向电阻率图版可以确定气层的电性下限并对气层进行有效识别。     

耐候钢耐蚀性能的评定

采用干湿浸渍实验获得耐候钢的防护性锈层.应用交流阻抗实验方法测试了所得的锈层,建立了等效电路分析数据.结果表明,交流阻抗方法可以有效地分析耐候钢内锈层的性质.干湿浸渍循环实验与交流阻抗方法相结合,可以快速、合理地评价耐候钢耐蚀性能.     

Cu-P-RE耐候钢的耐蚀性能

通过干湿周浸加速腐蚀实验研究了不同稀土含量的耐候钢和对比普碳钢的腐蚀行为及其耐蚀性能.采用失重法测得了各试样的腐蚀率;结果发现,稀土耐候钢的腐蚀率远远低于普碳钢的,不同稀土含量的耐候钢的耐腐蚀性不尽相同.采用电化学交流阻抗技术对带锈钢样的表面锈层结构及电化学反应过程进行了研究,提出在本实验条件下钢电化学腐蚀的等效电路模型,计算出锈层电阻、极化阻抗等表征锈层性能的电化学元件参数值.稀土耐候钢锈层中存在半无限扩散和有限厚度扩散两种过程,有限厚度扩散极化阻抗反映了耐候钢内锈层的保护性能.     

地衣和地衣酸与岩石矿物风化及其机制研究进展

岩石矿物风化是地球表面发生的最重要化学现象之一,其中生物风化备受关注。对地衣及地衣真菌分泌的地衣酸类物质(简称地衣酸)在岩石矿物风化中的作用及机制进行综合述评,从而为科学评价地衣和地衣酸在森林(特别是寒温带)生态系统中的作用提供理论依据。地衣通过物理和化学方式显著诱导并加速岩石矿物的风化进程,即同时具有生物物理风化和生物化学风化两方面作用,而后者更为重要。在地衣诱导的岩石矿物风化过程中,地衣依其共生真菌/藻类特异性分泌的地衣酸起主导作用,无论是在野外还是实验室条件下,地衣酸都是岩石矿物生物风化的主要作用力。地衣酸对岩石矿物的风化机制包括质子促进效应和络合促进效应两方面,特别是地衣酸能与岩石矿物中的盐基离子形成可溶性螯合物,从而引起岩石矿物的强烈溶蚀。     

Trace element geochemistry during chemical weathering

The granite weathering in Longnan, Jiangxi, is represented by mineralogical changes of feldspars → montmorillonite, illite → kaolinite, halloysite → bauxite, with Na, Ca, Si, P, V, U and Sr being in a mobile state while Ti, Al, Fe, Sc, Th, Zr and Hf remaining relatively conservative. With the exception of Zr/Hf, Nb/Ta, Th/Sc, Zr/Nd and Sm/Nb, changes are notable in ratios between most of the trace elements. Re-distribution of REE and Y has taken place during the chemical weathering, and the REE patterns of weathered samples in the profile, with original characters of the parent rock still recognizable, has undergone some fractionation. Generally, the extent of chemical weathering is the critical factor determining the mineralogical and chemical characteristics of the profiles and this must be taken into account in any study of tracing the provenance on the basis of mineralogical and trace element characteristics of the sediments.     

新疆尉犁金云母表生风化的实验模拟研究

本文在常压条件下模拟金云母蛭石化的地表风化环境，探讨金云母晶层向蛭石晶层转变的过程，研究不同氯化钠浓度下的混合溶液对金云母向蛭石转变过程的影响规律.本文采用XRD、XRF、ICP、SEM研究转化过程中物相、结构、化学成分和微观形貌的变化，利用TG-DSC研究转化前后样品的热学性质的变化，并测定了样品的阳离子交换容量（CEC）.研究结果表明，金云母经模拟环境溶液处理后，发生了金云母晶层向蛭石晶层转化的现象，转化过程表现为金云母结构中K⁺含量明显降低，结构中引入水化钠离子，层电荷数降低，CEC提高.本文的研究结果对于新疆尉犁蛭石矿床中低利用率的金云母矿物的开发利用具有一定意义.     

含钼耐候钢的腐蚀性能

通过显微组织观察、周浸加速腐蚀实验、锈层微观分析、锈层交流阻抗特征分析等方法,研究了合金元素钼含量对耐候钢腐蚀性能的影响.合金元素钼可以促进钢中贝氏体组织的形成,促使锈层更加致密,对钢基体具有更好的保护性,有利于提高钢的耐腐蚀性能.随着钢中钼含量的增加,实验钢锈层的腐蚀电位正移,自腐蚀电流密度减小,锈层的阳极溶解反应受到明显阻碍,锈层具有更好的保护性.     

川西雷口坡组古风化壳喀斯特气藏成藏条件

川西地区中三叠统雷口坡组顶部在近期钻探中呈现出良好油气显示。为了探究其油气成藏条件,通过岩石薄片观察、有机地化分析、同位素分析等技术手段,在前人研究的基础上对川西地区雷口坡组顶部古风化壳喀斯特气藏的成藏地质条件进行分析并恢复其油气成藏过程。结果表明,该类型气藏具备马鞍塘组与小塘子组2套烃源层系,油气源充足;雷顶古风化壳喀斯特储层次生孔洞发育,储集性能良好;气藏生储盖组合为:马鞍塘组与小塘子组烃源岩+雷顶古风化壳喀斯特储层+上三叠统泥质盖层,匹配关系好,保存条件佳;油气在运聚过程中受印支古隆起构造带及雷顶不整合面双重控制,气藏圈闭类型为构造-地层复合型圈闭;气藏在形成演化过程中经历了中三叠世末表生成岩孔隙建造期、晚三叠世中晚期有利于油气聚集的古隆起构造带形成期、燕山期古隆起构造带继承发育-油气大规模聚集期、喜马拉雅期气藏最终定型期4个重要阶段。川西地区雷口坡组古风化壳喀斯特气藏成藏条件较为优越,具有广阔的天然气勘探前景。     

Negligible glacial-interglacial variation in continental chemical weathering rates

Chemical weathering of the continents is central to the regulation of atmospheric carbon dioxide concentrations, and hence global climate. On million-year timescales silicate weathering leads to the draw-down of carbon dioxide, and on millennial timescales chemical weathering affects the calcium carbonate saturation state of the oceans and hence their uptake of carbon dioxide. However, variations in chemical weathering rates over glacial-interglacial cycles remain uncertain. During glacial periods, cold and dry conditions reduce the rate of chemical weathering, but intense physical weathering and the exposure of carbonates on continental shelves due to low sea levels may increase this rate. Here we present high-resolution records of the lead isotope composition of ferromanganese crusts from the North Atlantic Ocean that cover the past 550,000 years. Combining these records with a simple quantitative model of changes in the lead isotope composition of the deep North Atlantic Ocean in response to chemical weathering, we find that chemical weathering rates were two to three times lower in the glaciated interior of the North Atlantic Region during glacial periods than during the intervening interglacial periods. This decrease roughly balances the increase in chemical weathering caused by the exposure of continental shelves, indicating that chemical weathering rates remained relatively constant on glacial-interglacial timescales. On timescales of more than a million years, however, we suggest that enhanced weathering of silicate glacial sediments during interglacial periods results in a net draw-down of atmospheric carbon dioxide, creating a positive feedback on global climate that, once initiated, promotes cooling and further glaciation.     

Developing space weathering on the asteroid 25143 Itokawa

Puzzlingly, the parent bodies of ordinary chondrites (the most abundant type of meteorites) do not seem to be abundant among asteroids. One possible explanation is that surfaces of the parent bodies become optically altered, to become the S-type asteroids which are abundant in the main asteroid belt. The process is called 'space weathering'-it makes the visible and near-infrared reflectance spectrum of a body darker and redder. A recent survey of small, near-Earth asteroids suggests that the surfaces of small S asteroids may have developing stages of space weathering. Here we report that a dark region on a small (550-metre) asteroid-25143 Itokawa-is significantly more space-weathered than a nearby bright region. Spectra of both regions are consistent with those of LL5-6 chondrites after continuum removal. A simple calculation suggests that the dark area has a shorter mean optical path length and about 0.04 per cent by volume more nanophase metallic iron particles than the bright area. This clearly shows that space-weathered materials accumulate on small asteroids, which are likely to be the parent bodies of LL chondrites. We conclude that, because LL meteorites are the least abundant of ordinary (H, L, and LL) chondrites, there must be many asteroids with ordinary-chondrite compositions in near-Earth orbits.     

三元乙丙橡胶的人工气候老化

利用氙灯人工气候箱对三元乙丙橡胶(EPDM)进行人工气候老化实验,采用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、电子万能试验机和色度计研究了人工气候老化对EPDM化学结构、表面形貌、力学性能和颜色的影响. 结果表明:在氙灯人工气候环境中老化90d后,EPDM表面生成一层厚度约2μm的氧化膜,其组成包括有C-O-C/C-OH、CO和O-CO;交联密度随老化时间的变化基本呈线性增加;随老化时间的延长,试样表面粗糙度增加,有孔洞和微裂纹生成,拉伸强度、撕裂强度和硬度增加,EPDM试样表面变红变黄,亮度增加.     

CSP工艺含钛耐候钢中的纳米磷化物

应用透射电镜(TEM)和X射线能谱(EDX)对CSP工艺含钛耐候钢中的细小磷化物进行了研究.对成品钢板和经900℃压缩20%并等温30min的连铸坯分析结果表明:耐候钢中存在MxP型纳米级磷化物,x值为2～3,金属元素M为Fe、Ti及少量Cr或Ni,磷化物的结构为六方晶系,点阵常数a=0.609nm、c=0.351nm;成品钢板中磷化物尺寸多在20nm以下,而经过900℃压缩的连铸坯试样中磷化物的尺寸、形状不尽相同,较大的棒状磷化物长约300nm、宽约50nm,其他粒子在50nm以下,多呈方形.CSP工艺生产线中可能发生磷化物沉淀的阶段是热连轧的最后两个道次直至冷却到400～500℃的过程中;磷化物的析出可提高沉淀强化效果,但同时会使钢中的固溶磷浓度降低.     

有机涂层室内加速实验的对比

研究了丙烯酸聚氨酯清漆涂层在荧光紫外UVA辐照/凝露和氙灯辐照/雨淋两种加速实验程序下的物理、化学性能和防护屏障性与暴露时间的关系.结果表明:氙灯辐照/雨淋对涂层的膜厚损失、失光率的影响程度略大于同周期UVA加速的效果;而黄色指数及不同暴露周期的完整涂层的低频阻抗模值与暴露时间的关系则与FTIR反映的羰基指数的变化规律较为一致,显示UVA加速涂层老化的效果大于同周期氙灯加速效果.且在两种加速条件下,完整涂层的低频阻抗模值均与暴露时间呈指数规律衰减,表现出较好的时间函数关系;说明EIS的低频阻抗模值与UV光辐射产生的涂层性能的变化有一定的相关性,并很好地反映其防护屏障性,可作为有效的监测参量用于建立室内外老化实验的相关性,预测光老化涂层的防护寿命.     

环氧树脂耐候性能的研究

以光稳定剂GW-682、抗氧剂KY-1010、紫外线吸收剂UV-531等抗老化助剂为主,对环氧树脂浇铸体的耐老化性能进行研究,研究其对环氧树脂老化行为的影响,并利用DSC和红外光谱分析手段研究了不同配比的抗老化助剂对环氧树脂浇铸体老化过程的影响,并测定了光老化过程中环氧树脂稳定剂体系物理机械性能,确定了最佳的光稳定剂、抗氧剂、紫外线吸收剂配比。     

湖南白垩系泥质粉砂岩风化特性研究

为了研究白垩系泥质粉砂岩的风化特性,对不同风化程度的泥质粉砂岩岩体进行了工程特性、风化耐久性和风化速度试验.试验结果表明:随着岩体风化程度的加深,岩石中粘土矿物含量增加,增幅达52.7%;活动性强的化学成分相对减少,含量由7.58%降到1.98%;岩石干密度降低,由2.58 g/cm3降为2.31 g/cm,;孔隙率由3.8%增至17.3%;吸水率由1.96%增至2.76%,力学性能降低,抗压强度由5.2 MPa降至1.8 MPa,抗拉强度由2.24 MPa降至0.27 MPa;岩体更容易软化崩解.岩石的风化速率与自身的风化状态和暴露的面积有关.表9,参6.     

表生喀斯特作用对蓬莱花岗岩潜山油田风化壳储层发育的控制作用

蓬莱9-1油田位于庙西北凸起,是罕见的大型中生界花岗岩油田,储层发育规律是制约勘探开发的关键问题。通过对岩体进行岩心、测井和化学测试资料综合分析,结果表明,花岗岩潜山风化壳在垂向上依次可划分出土壤层、砂化层、砂化砾石层、裂缝带和基岩;不同带中储集空间类型不同,砂化层以孔隙型储层为主,砂化砾石层以裂缝型+孔隙型储层为主,裂缝带以裂缝型储层为主;从砂化层到裂缝带,储层的孔隙度逐渐降低,裂缝越来越发育,储层的渗透率从裂缝带到砂化层和基岩带依次降低;优质储层主要发育于砂化层、砂化砾石层和裂缝带中,储集空间类型主要为裂缝-孔洞型;储层的孔隙度主要受表生喀斯特作用(包括风化作用)控制,裂缝主要受变形强度和断裂的控制。砂化层、砂化砾石层的厚度受表生喀斯特作用控制,裂缝带的发育与构造作用密切相关。砂化砾石层和裂缝带以高的渗透率和最大的厚度而成为风化壳型潜山最为重要的储层。     

Jarosite as an indicator of water-limited chemical weathering on Mars

The Mars Exploration Rover Opportunity identified the ferric sulphate mineral jarosite and possible relicts of gypsum at the Meridiani Planum landing site. On Earth, jarosite has been found to form in acid mine drainage environments, during the oxidation of sulphide minerals, and during alteration of volcanic rocks by acidic, sulphur-rich fluids near volcanic vents. Jarosite formation is thus thought to require a wet, oxidizing and acidic environment. But jarosite on Earth only persists over geologically relevant time periods in arid environments because it rapidly decomposes to produce ferric oxyhydroxides in more humid climates. Here we present equilibrium thermodynamic reaction-path simulations that constrain the range of possible conditions under which such aqueous alteration phases are likely to have formed on Mars. These calculations simulate the chemical weathering of basalt at relevant martian conditions. We conclude that the presence of jarosite combined with residual basalt at Meridiani Planum indicates that the alteration process did not proceed to completion, and that following jarosite formation, arid conditions must have prevailed.