石膏对白云岩溶解影响的实验模拟研究

表生到埋藏成岩作用的温度与压力（４０-１３０℃、常压－３０ＭＰａ）条件下，含膏与不含膏白云岩的溶解实验证明:在表生与相对浅埋藏的温压条件（低于７５℃，２０ＭＰａ）下，石膏（或硬石膏）的存在可不同程度地加速白云岩的溶解，随着实验温度和压力的升高，石膏（或硬石膏）对白云岩溶解的这种积极作用逐渐降低。在相对深埋藏的温压条件（高于７５℃、２０ＭＰａ）下，石膏（或硬石膏）的存在显著阻止白云岩的溶解，随着实验温度和压力的继续升高，石膏（或硬石膏）对白云岩溶解的这种消极作用也逐渐增加。从实验的这种结果可以预测，在近地表条件下和埋藏成岩作用的早期阶段，由溶解作用造成的含膏白云岩地层的次生孔隙将比不含膏的白云岩地层更为发育，因而在经历了古风化作用的地层中，含膏白云岩层更易形成良好的储层；与之相反，在相对高温高压的深埋藏成岩阶段，不含膏的白云岩地层中将更容易因酸性水的溶解作用而形成次生孔隙。因而在非蒸发沉积环境中形成的白云岩体（如正常海沉积环境的灰岩中的白云岩透镜体）更易因深埋藏溶蚀作用而形成良好的储层。     

湖北宜昌地区寒武系岩石学特征及沉积环境

鄂西宜昌地区寒武系出露齐全、连续，且岩石类型多样、化石丰富，是我国寒武系的标准剖面之一。其沉积环境以潮下高能浅滩为主，其次为间歇能量的潮间带、滨岸的中小型浅滩，少数为开阔海较深处的静水灰泥沉积。石灰岩集中分布于下寒武统天河板组和水井沱组，其次在下寒武统的石牌组、中寒武统的磕膝包组、官山瑙组有少量夹层出现。其岩石类型有颗粒灰岩（鲕粒灰岩、核形石灰岩、砾屑灰岩及砂屑灰岩）、含颗粒泥粉晶灰岩（含生屑泥粉晶灰岩、含生屑灰岩）及泥晶灰岩。白云岩是本地区数量最多的岩石类型。从下寒武统石龙洞组开始都是白云岩沉积，白云岩可据白云石化作用机理和时间的不同分为准同生白云岩和准同生后白云岩两大类。准同生白云岩广泛出现于中上寒武统，岩石呈土黄色、砖红色，具纹层、鸟眼、干裂构。准同生后白云岩根据残余颗粒的有无可分为残余颗粒白云岩和晶粒白云岩两大类。晶粒白云岩有两种成因。一为回流渗透云化；二为深埋藏云化。根据本区寒武系岩石的岩石学特征、生物组合特征和结构构造特征本文重建了各组段的沉积环境.     

近百年来洱海沉积物有机碳埋藏时空变化

湖泊沉积物有机碳埋藏是陆地碳循环中重要的环节,对全球碳平衡起着重要的作用.洱海是云贵高原第二大淡水湖,目前对洱海生态环境变化、重金属与营养盐污染等已展开了较为深入的研究,但对近百年来沉积物有机碳埋藏时空变化与驱动因素缺乏系统的分析.本文通过对洱海北部湖区典型岩芯（编号EH2012）以及其他湖区13个沉积岩芯中有机碳（OC）含量的分析,结合湖泊生态环境与气候因子变化,研究了近百年来沉积物有机碳埋藏时空变化特征与影响因素.C/N摩尔比值表明洱海沉积物中OC以湖泊内源为主,不同湖区岩芯中OC含量变化趋势基本相似.以EH2012岩芯为例,OC含量历史变化可分为3个阶段：1970年以前,表现出较稳定的低值;1970-2000年,OC含量逐渐增加;2000年以来,OC含量增加更加明显并达到近百年来的最大值.近百年来,EH2012岩芯有机碳累积速率（OCAR）呈逐渐增加趋势,变化范围为7.9~87.2 g/（m²·a）,平均OCAR（OCAR）为24.1 g/（m²·a）;OCAR变化与OC含量和区域气温呈显著正相关,全球变暖与营养驱动下的湖泊生产力提高可能是近年来OCAR增加的主要原因之一.基于重金属Cd污染初始时间建立的时标,1982年以来不同湖区OCAR为17.1~44.7 g/（m²·a）,采用克里金插值得到的全湖OCAR均值为31.4 g/（m²·a）;不同湖区OCAR与磷累积速率呈显著正相关,指示了湖泊营养水平对有机碳埋藏空间变化的重要影响.     

Effects of long soil surface residence times on apparent cosmogenic nuclide denudation rates and burial ages in the Cradle of Humankind,South Africa

In situ cosmogenic nuclides are an important tool for quantifying landscape evolution and dating fossil-bearing deposits in the Cradle of Humankind (CoH), South Africa. This technique mainly employs cosmogenic 10-Beryllium (¹⁰Be) in river sediments to estimate denudation rates and the ratio of 26-Aluminium (²⁶Al) to ¹⁰Be (²⁶Al/¹⁰Be), to constrain ages of sediment burial. Here, we use ¹⁰Be and ²⁶Al concentrations in bedrock and soil above the Rising Star Cave (the discovery site of Homo naledi) to constrain the denudation rate and the exposure history of soil on the surface. Apparent ¹⁰Be-derived denudation rates obtained from pebble- to cobble-sized clasts and coarse-sand in soil (on average 3.59 ± 0.27 m/Ma and 3.05 ± 0.25 m/Ma, respectively) are 2-3 times lower than the bedrock denudation rates (on average 9.46 ± 0.68 m/Ma). In addition, soil samples yield an average ²⁶Al/¹⁰Be ratio (5.12 ± 0.27) that is significantly lower than the surface production ratio of 6.75, which suggests complex exposure histories. These results are consistent with prolonged surface residence of up to 1.5 Ma in vertically mixed soils that are up to 3 m thick. We conclude that the ¹⁰Be concentrations accumulated in soils during the long near-surface residence times can potentially cause underestimation of single-nuclide (¹⁰Be) catchment-wide denudation rates in the CoH. Further, burial ages of cave sediment samples that consist of an amalgamation of sand-size quartz grains could be overestimated if a pre-burial ²⁶Al/¹⁰Be ratio calculated from the surface production is assumed. © 2019 John Wiley & Sons, Ltd.     

海相烃源岩的正反演对比分析

海相优质烃源岩有效的评价体系是海相地层油气勘探开发中的关键问题之一.沉积盆地内保存的残余有机质从生物物质到烃源岩的演化过程经历了两个阶段, 即从生物物质到沉积有机质的形成阶段和从沉积有机质到残余有机质的烃源岩形成阶段, 后者包括沉积有机质在未熟阶段经历生物化学作用成为埋藏有机质和在成熟-过成熟阶段经历热解作用成为残余或风化残余有机质两个亚阶段.烃源岩反演分析是利用残余或风化残余有机质的量来推断埋藏有机质的量或者原始生烃潜力.而正演分析则是根据沉积物沉积环境、生物物质及其介质物理化学条件特征运用地球生态学、地球微生物学、分子地球生物学和生物地球化学方法推断沉积有机质的量, 甚至推断埋藏有机质的量, 进而评估烃源岩的原始生烃潜力, 也就是利用生物生产力和保存环境等综合分析沉积有机质的量.正反演对比分析相互验证和相互补充, 更好地揭示了烃源岩基本特征, 为海相优质烃源岩的预测和评价提供了有效的研究方法.      

Recovery of topsoil physicochemical properties in revegetated sites in the sand-burial ecosystems of the Tengger Desert, northern China

Recovery in soil properties and processes after sand burial in the Tengger Desert, northern China, was documented at five different-aged revegetated sites (1956, 1964, 1973, 1982, and 1991) and at a reference site with native vegetation, which had never been damaged by sand burial and was enclosed for grazing. The proportions of silt and clay, depth of topsoil and biological soil crusts, and concentrations of soil organic C, K, total N and total P increased with years since revegetation. Most characteristics of topsoil (0–5 cm) characteristics had recovered to 60% of those measured at the reference site by 50 years after sand-binding vegetation had been established. Exceptions were electrical conductivity and contents of sand, silt, CaCO₃ and organic C, which recovered to 20–40% of the values at the reference site. The difference in annual recovery rates of soil properties between the two most recently revegetated sites (0–14 years) was greater than the difference between the two oldest revegetated sites (43–50 years). Best-fit asymptote models showed that the estimated times for the soil properties in the 50-year-old site to reach the same levels as in the reference site (i.e. an undisturbed, native steppified desert ecosystem) would be between 23 and 245 years, but for some properties even maximum recovery after > 50 years still fell significantly short of the level at the reference site. These results suggest that soil recovery is a slow process in an extremely arid desert environment, and therefore the conservation of soil habitat is a crucial issue for land managers.     

试论河南省济源西部煤田地质特征及找矿方向

煤是国家高度重视和急需勘查开发的重点能源矿种，后备资源的充足与否，事关国家能源安全。济源西部地区有大面积的石炭、二叠系含煤地层分布，并且含煤层数多，煤层较为稳定，具有较好的找矿前景。通过对济源西部地质特征、煤田聚煤作用、煤系地层及埋藏条件的分析，提出了在该区的找煤方向。     

Dolomitization of the Middle Devonian Winnipegosis carbonates in south-central Saskatchewan, Canada

The Middle Devonian Winnipegosis carbonate unit in south‐central Saskatchewan is partially to completely dolomitized. Two major types of replacive dolomite are distinguished. Microcrystalline to finely crystalline dolomite (type 1) displays nonplanar‐a to planar‐s textures, mimetically replaces the precursor limestone, accounts for about four‐fifths of dolomite phases volumetrically, and mainly occurs in the Winnipegosis mounds and the Lower Winnipegosis Member directly underlying the mounds. Medium crystalline dolomite (type 2) shows planar‐s to planar‐e textures, commonly occurs in the Lower Winnipegosis and Brightholme members, and decreases upward in abundance. The ⁸⁷Sr/⁸⁶Sr ratios of type 1 dolomite (0·70795 to 0·70807) fall within the estimated Sr‐isotopic range for Middle Devonian marine carbonates. Stratigraphic, petrographic and geochemical data constrain the formation of type 1 dolomite to hypersaline sea water in a near‐surface environment, after marine cementation and sub‐aerial diagenesis and prior to precipitation of the Middle Devonian Leofnard salts. Movement of dolomitizing fluids could be driven by density differences and elevation head. The shift to lower δ¹⁸O values of type 1 dolomite [?7·4 to ?5·1‰ Vienna Pee Dee Belemnite (VPDB)] is interpreted as the result of recrystallization at elevated temperatures during burial. Type 2 dolomite has higher ⁸⁷Sr/⁸⁶Sr ratios (0·70809–0·70928), suggesting that the dolomite probably formed from basinal fluids with an increased richness in the radiogenic Sr isotope. In type 2 dolomite, Sr²⁺ concentrations are lower, and Fe²⁺ and Mn²⁺ concentrations are higher, compared with the associated limestone and type 1 dolomite. Type 2 dolomite is interpreted as having been formed from upward‐migrating basinal fluids during latest Devonian and Carboniferous period.     

从波动观点看塔北地区油气藏的形成演化：以英买7油藏为例

本文运用沉积波动过程分析方法,在综合分析野外露头、岩心、录井、测井、地震等资料的基础上,建立了塔北地区不同小区的岩性－时间剖面。研究表明,７４０￣７６０Ｍａ、２００￣２４０Ｍａ、１００￣１１０Ｍａ、６０￣７０Ｍａ、３０Ｍａ是控制塔北地区构造演化的主要周期。早古生代、三叠纪和第三纪以来是３次主要的沉积高峰,志留纪末－晚泥盆世早期为主要肃蚀期,肃蚀量一般〉１０００ｍ,北部〉１５００￣２０００ｍ,海西期     

孙虎地区埋藏史分析及与油气关系研究

埋藏史研究是含油气系统研究的核心内容 ,是研究油气的生、运、聚及成藏过程的关键。在区域背景分析的基础上 ,定量计算了孙虎地区各地层单元的剥蚀厚度 ;通过压实、剥蚀恢复动态地分析了源岩层的埋藏史 ;结合源岩生烃门限分析 ,分析了单井和平面上源岩的生、排烃期。认为孙虎地区存在 3种类型的埋藏史 ;由于二次沉降的幅度小 ,未能超过第一次沉降的幅度 ,所以本区不存在二次生烃问题