Diurnal and seasonal variation in physico-chemical conditions within intertidal rock pools     

S. Morris  A.C. Taylor 《Estuarine, Coastal and Shelf Science》1983,17(3):339-355

A study of the diurnal and seasonal variation in the physico-chemical conditions within intertidal rock pools on the West coast of Scotland was undertaken to provide data on the environmental conditions experienced by animals inhabiting these pools. The temperature, pH, partial pressure of oxygen (P_O2) and salinity were measured every hour for 24 h and the total alkalinity, partial pressure of carbon dioxide (P_CO2) and carbon dioxide content (C_CO2) calculated. This sampling regime was carried out once a month for 12 months to determine the extent of seasonal variation in conditions within temperate pools.Large diurnal variations were recorded in nearly all the physico-chemical parameters measured. The greatest variation was recorded in the temperature and P_O2 of the water but significant changes in pH and P_CO2 were also recorded. Total alkalinity varied little during any 24 h period but carbonate alkalinity, which was always lower than total alkalinity, showed slightly greater variation. There was also considerable variation in the magnitude of these diurnal changes between pools at different heights on the shore.Diurnal variation in the physico-chemical conditions within the pools were observed throughout the year although the magnitude of these changes varied seasonally. Detailed studies on individual pools demonstrated that appreciable local variation existed in the physico-chemical conditions within each pool.  相似文献   

川西坳陷中段上三叠统须家河组二段原油裂解成因天然气发现及成藏模式初探     

刘四兵  沈忠民  吕正祥  罗小平  冷济高 《沉积学报》2012,30(2):385-391

川西坳陷中段具备多套烃源层、多个烃源区、多期油气生成、多期油气成藏同时又经历了多个构造期调整和破坏,纵向上发育的多套生储盖组合孕育了多层含气层系。天然气碳同位素分析表明,该区上三叠统须家河组产出的部分天然气乙烷碳同位素具有明显偏负的特征,相关图版的判别显示,这部分天然气具有原油裂解气的性质。同时在研究区上三叠统须家河组储层中发现了大量的储层沥青充填物,通过岩芯观察、显微照片、元素、热解等分析,发现该储层沥青充填物具有多种类型、多种分布形态、边界较为清楚等特征,且这些沥青充填物的反射率较高,尤其是须二段的储层沥青,这一特征与焦沥青的基本特征类似,表现为油藏裂解后残余物的特征,原油裂解气和焦沥青的发现证实了川西坳陷中段须家河组古油藏的存在。在此基础上,通过综合分析生油及裂解条件等,对研究区须家河组古油藏裂解气成藏模式进行了初步探讨,将这一过程分为印支晚期古油藏形成、燕山中期古油藏裂解、燕山晚期-喜山期气藏调整三个连续的阶段,这对深化认识川西坳陷中段天然气的成因和分布具有一定的意义。  相似文献   

The bed morphology of upland single‐thread channels in semi‐arid environments: evidence of repeating bedforms and their wider implications for gravel‐bed rivers     

D Mark Powell  Jonathan B Laronne  Ian Reid  Ronel Barzilai 《地球表面变化过程与地形》2012,37(7):741-753

Single‐thread, gravel‐bed streams of moderate slope in the northern Negev are characterized by three channel units: bars exhibit steeper than average slopes and poorly sorted mixtures of small–medium cobbles and coarse–very coarse pebbles; flats are associated with more gentle slopes and well‐sorted medium–fine pebbles and granules; and transitional units have intermediate slopes and grain size. In general, all three units are planar, span the full channel width and have well‐defined boundaries. Bars and flats are more common than the transitional units and alternate downstream for distances of several hundred metres, forming sequences that are reminiscent of the riffle–pool structure commonly observed in humid‐temperate gravel‐bed rivers. A notable contrast is the absence of significant bed relief: bars lack crests and flats lack depressions. The relative lack of bed relief in bar–flat sequences is attributed to the high rate of sediment supply from the sparsely vegetated hillslopes which promotes the infilling of depressions and to the erosion of crests under conditions of intense transport. This reduction of bed relief lowers channel roughness, which in turn increases flow velocity and, therefore, the ability of the channel to transmit the large sediment loads it receives. Although our analyses pertain to a semi‐arid river system, the results have wider implications for understanding the adjustment of channel bedform to high sediment loads in other fluvial environments. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

济阳坳陷高青—平南断裂带CO_2气藏中稀有气体地球化学特征     

申宝剑  秦建中  胡文碹  黄智龙  王杰 《高校地质学报》2009,15(4)

济阳坳陷高青-平南发育多个CO_2气藏,对气藏组分、同位素以及组分同位索相关组合进行分析,认为气藏中CO_2主要是幔源-岩浆成因.气藏同时具有高~(40)Ar/~(36)Ar和高~3He/~4He值表明:气藏中稀有气体主要来自幔源,同时有部分壳源混入;气藏中~4He/~(40)Ar~*平均值为2.15,说明该地区气藏形成主要以岩浆缓慢脱气为主,大规模CO_2及稀有气体是岩浆冷却结晶阶段所释放.其形成机理为:在随岩浆上升的过程中,随着压力和温度不断下降以及岩浆成分的变化,岩浆中CO_2及稀有气体溶解度也随之降低并析出,产生的大量CO_2及稀有气体沿着深大断裂及一些二、三级断裂交汇处输送至地层的各类圈闭中,并在适当的位置聚集成藏.  相似文献   

准噶尔盆地南缘天然气成因与成藏解剖   总被引：18，自引：1，他引：17  

李延钧  王廷栋  张艳云  陈世加  王绪龙 《沉积学报》2004,22(3):529-534

利用全烃地球化学方法,结合准噶尔盆地南缘三排构造特点,在确认油气源和天然气成因的基础上,对呼图壁气田、吐谷鲁和齐古油气田进行了成藏历史分析和解剖.研究表明各构造带不仅捕获了喜山期侏罗系高熟煤成气,这是该区天然气成藏的关键,而且还聚集有燕山期侏罗系低成熟-成熟阶段的油气,但不同构造带对这一阶段的油气的聚集量、方式和保存作用不同,第一排构造直接捕获大量侏罗系低成熟-成熟油气,但天然气的散失严重;第二、三排构造存在白垩系-下第三系中转侏罗系低成熟-成熟油气的特征.最后阐述了准噶尔盆地南缘进一步寻找天然气的勘探方向.  相似文献   

河北黄骅坳陷沈家铺地区孔一段火成岩油气特征     

张世奇  纪友亮  石占中 《高校地质学报》2001,7(4):466-474

根据地震剖面解释，结合岩芯观察，钻井，测井及试油等资料，从火成岩的岩性，电控特征，火成岩空间分布特征，储集特征及其含油气特征等方面，对浓家铺地区孔一段火成岩的分布规律及其油气特征进行了研究。该区主要发育火山喷发岩和浅成侵入岩，它们分别分布于孔西断层的下降盘和上升盘，并形成以孔隙和裂缝为主要储集空间的火山喷发岩油气藏和以烈缝为主要储集空间的浅成侵入岩油气藏。  相似文献   

川东石炭系大气田成藏条件分析   总被引：14，自引：0，他引：14  

徐国盛  左友东  张文虎 《矿物岩石》2001,21(4):59-64

川东地区是四川盆地稳定地块中的相对构造活动带，区内发育10排高陡构造带，90年代以来高陡构造带石炭系成组气田勘探获得巨大突破。本文着重讨论了石炭系气藏的成藏条件，指出形成石炭系大气田的各项有利条件，即具丰富气源的志留系、二叠系存在异常高压提供足够的动力促使天然气向区域孔洞型储集层石炭系常压层运移，高陡构造带成串分布的高点是形成成组气田的有利圈闭，石炭系在上覆阳新统高压封闭体系的严密保护下聚集成藏。  相似文献   

济阳坳陷地温—地压系统特征及其对油气藏分布的控制作用   总被引：15，自引：17，他引：15  

刘震  戴立昌  赵阳  许晓明  张善文  蔡进功 《地质科学》2005,40(1):1-15

济阳坳陷发育两类复式温—压系统,即高压型复式温—压系统和低压型复式温—压系统。主要生烃凹陷同一层段的温—压系统平面分区特征在横向上有较大的变化:高压型复式温—压系统促使与断层有关的油气藏富集在中浅层,低压型复式温—压系统造成与断裂有关的油气藏可以发育在相对深层;高压型复式温—压系统可以产生长距离运移,而低压型复式温—压系统只能发生短距离运移。温—压系统控制油气藏分布,油气藏分布在相对低能区。  相似文献   

鄂尔多斯盆地油气地质与勘探     

杨华  付锁堂  魏新 《应用地球物理》2004,1(2):103-109

鄂尔多斯盆地油气资源丰富,盆地构造平缓,以岩性、岩性-地层和古地貌油气藏为主,储层厚度薄。本文详细分析了鄂尔多斯盆地油气地质、油气资源的形成与分布,指出了鄂尔多斯盆地油气勘探方向及地震勘探技术系列在该盆地大油气田的发现中的不可替代的重要作用。  相似文献   

含油气盆地中高地温的地质意义   总被引：4，自引：1，他引：4  

李春光 《现代地质》1993,7(4):472-478

本文以渤海湾油区南部含油气盆地为例,讨论了地温对盆地生油、砂岩孔隙性和特殊油、气藏形成的地质作用和意义。地热研究不仅限于学科自身的范围,而且已向石油、天然气等流体矿藏的成藏领域突入,并从已知的深层原生天然气藏、高含二氧化碳的天然气藏、特高压油藏和特稠油油藏的成藏实例中,找到了某些结合点。  相似文献