从端点走向连续:河流沉积模式研究进展述评

从河道类型的划分、河床演变与河型转换、河道沉积与河流砂体的建筑结构要素、河漫滩沉积、季节性河流与分支河流体系、河流沉积相模式、河流沉积学研究技术与方法等方面对国内外河流沉积模式的研究进展进行了综述,认为近十年来河流沉积学的理论和方法都发生了重要的变化。地貌学家、沉积学家和工程师认识到河道形态是连续可变的,而不是只有4~40多个端点类型。河床的演变受河床比降、流量变幅、河岸沉积物粒度构成、气候、植被以及构造沉降速率等多方面的影响。垂向剖面分析法难以对古河流类型做出正确的判断,运用建筑结构要素分析法重建河道内大型底形的地貌形态是河型判别和河流相模式重建的正确方法。河漫滩是河流沉积事件记录最为齐全的部位,对河漫滩、天然堤和泛滥平原沉积层序的研究能够揭示更多古河流沉积过程以及古环境、古气候和古生物方面的信息。对季节性河流、受季风强烈影响地区的河流、以及不同气候带河流所发育的独特沉积构造和建筑结构要素的研究不断增加。分支河流体系的概念得到越来越多的应用,但也得到不少质疑。我国学者应当注重对现代河流地貌形态和沉积过程的观察,把河床演变学的定量方法与沉积学的观点、理论和资料相结合,利用露头、三维地震资料和探地雷达技术建立河流砂体内部建筑结构信息数据库,加强对古河流河漫滩和泛滥平原的沉积过程、特征及其控制因素的研究,加强对不同构造和气候条件下河流沉积的差异性研究,不断发展河流沉积学研究技术,加强河流沉积学实验室建设和研究队伍建设,加强国际交流与合作,使我国河流沉积学为国家经济社会发展提供更加有力和有效的支撑,为推动国际河流沉积学发展做出中国人自己的贡献。     

粒度端元模型在新疆黄土粉尘来源与古气候研究中的初步应用

基于新疆伊犁盆地肖尔布拉克黄土剖面粒度数据,以贝叶斯粒度端元模型法为主,粒级标准偏差法为辅探寻对气候变化响应敏感的粒级组分及其对粉尘来源示踪和古气候重建的意义。研究结果表明粒度端元组分EM1（众数粒径:21.22 μm）代表大气粉尘中较为稳定的背景值,其含量的变化与高空西风环流强度有关。EM2（75.29 μm）主要代表了近源河流沉积物的悬移搬运组分,可视为较敏感的古气候指标。EM3（47.5 μm）也代表了近距离的悬移搬运组分,可能主要由较粗颗粒对地表的碰撞磨蚀作用而产生。EM2记录了深海氧同位素2阶段（MIS2）以来的北大西洋气候波动事件,如Heinrich事件、YD事件等。贝叶斯粒度端元模型能够区分不同的沉积动力过程,在新疆黄土古气候研究中具有广泛的应用前景。     

下寺湾油田长8段储层相控建模研究

运用Petrel储层建模软件,对下寺湾油田长8段砂组进行储层相控建模研究。首先利用序贯指示模拟方法建立能够表征储层较大规模非均质性的沉积微相模型;在沉积微相模型建立之后,采取相控物性参数建模方法,分小层分微相统计各种物性参数分布特征;然后利用序贯高斯模拟方法分别进行模拟,建立了研究区的孔隙度模型、渗透率模型和含油饱和度模型。结果证明按此方法建立的模型效果较好,客观反映了地质实际,为该区下一步滚动勘探开发提供了地质依据。     

接近于铁橄榄石端员组份的铁橄榄石集合体的发现及其初步研究

铁橄榄石集合体为无根岩石。外观呈铁黑色,风化面呈亮栗褐色。本文对铁橄榄石集合体的形态特征、物理性质和化学成分进行了研究。通过化学式的计算,其化学式为:(Mg_(0.0168)Fe_(0.9802)Mn_(0.003))_2[SiO_4],证明其为铁橄榄石的端员组份。此外,还对其进行了穆斯堡尔谱分析、X射线粉晶衍射分析和红外光谱分析。其穆斯斑堡尔谱分析结果与人工合成的铁橄榄石数据相近,它的衍射数据及计算的晶胞参数也与JCPDS所提供的标准数据非常接近,这些进一步证明了铁橄榄石集合体的成分接近于铁橄榄石端员组份。     

Differential Models for Evolutionary Compositions

General systems are frequently decomposable into parts and these parts can evolve in time or space, a frequent occurrence in the field of Geosciences. In most cases, fitting models to forecast future states of the system is a goal of the analysis. Modelling interactions between parts may also be of common interest. The system can be analysed from different points of view; the traditional one consists in modelling each part of the system in time. Alternatively, modelling the evolution of the parts as proportions is proposed herein and attention is centred on the compositional evolution. The compositions are expressed in orthogonal coordinates (ilr) and then modelled using first-order differential equations with constant coefficients. Simple models are shown to be very flexible, including many of the standard growth curve models. The models are fitted using regression techniques on the integrated coordinates. The use and interpretation of these differential models is illustrated with several examples: a simulated example; urban waste in Catalonia (Spain); oil production and reserves; and growth of a luzonite crystal.     

一种面向对象的三维地下空间矢量数据模型

针对地下空间的真三维连续特性以及建模过程的动态交互编辑与分析要求,提出了一种新的三维地下空间矢量数据模型。该模型采用面向对象思想对地下各种空间对象进行抽象描述;利用模型中的线段要素增强几何元素之间拓扑连接关系的维持,为地质体的切割和地下工程体的开挖等分析提供了算法上的便利;引入拓扑面更好地表达了地下空间对象之间的拓扑邻接关系。该模型在三维地下空间数据的存储管理、查询分析以及实时逼真绘制等方面都表现出较好的性能,适用于地下勘探工程的建模与分析。     

An Approach for Modeling Rock Discontinuous Mechanical Behavior Under Multiphase Fluid Flow Conditions

In this paper, the two computer codes TOUGH2 and RDCA (for “rock discontinuous cellular automaton”) are integrated for coupled hydromechanical analysis of multiphase fluid flow and discontinuous mechanical behavior in heterogeneous rock. TOUGH2 is a well-established code for geohydrological analysis involving multiphase, multicomponent fluid flow and heat transport; RDCA is a numerical model developed for simulating the nonlinear and discontinuous geomechanical behavior of rock. The RDCA incorporates the discontinuity of a fracture independently of the mesh, such that the fracture can be arbitrarily located within an element, while the fluid pressure calculated by TOUGH2 can be conveniently applied to fracture surfaces. We verify and demonstrate the coupled TOUGH–RDCA simulator by modeling a number of simulation examples related to coupled multiphase flow and geomechanical processes associated with the deep geological storage of carbon dioxide—including modeling of ground surface uplift, stress-dependent permeability, and the coupled multiphase flow and geomechanical behavior of fractures intersecting the caprock.     

Fe Isotope Compositions of Cyprus Umbers

Submarine metalliferous sedimentary rocks are chemical precipitates resulted from hydrothermal exhalation near mid‐ocean ridge or faults. They record the submarine hydrothermal activity between lithosphere and hydrosphere and are critical for understanding Fe cycling in marine environment. Fe was expelled from the hydrothermal vent systems and was oxidized and precipitated in the ambient seawater, where the precipitation of hydrothermal Fe is largely controlled by oxidation state of seawater and is potentially revealed by its Fe isotope compositions. This hydrothermal process in modern hydrothermal vent systems have been well observed, but that for the ancient ones are still not well known. Umbers, or ferromanganoan sediments, overlying Troodos ophiolite in Cyprus of Mid‐Cretaceous age thus provides an excellent example for understanding the Fe cycles in ancient submarine hydrothermal process. Samples were collected from Margi village in Troodos and are mostly amorphous Fe‐Mn oxy‐hydroxides with very minor quartz, goethite, smectite and silicates such as clinopyroxene derived from the volcanic rocks. There is no terrestrial, detrital component. Samples were analyzed for their whole‐rock element and Fe isotope compositions. The results show that samples are composed mainly of SiO₂ (13～80 wt%), Fe₂O₃ (9～54 wt%) and MnO (1.5～10.4 wt%), with minor Al₂O₃ (0.7～4.3 wt%). PAAS‐normalized REE patterns are near flat with significantly negative Ce anomalies (Ce/Ce* is from 0.2 to 0.5) and slightly positive Eu anomalies (Eu/Eu* is around 1.1), indicating a source from the oxidized seawater and the high‐temperature hydrothermal fluids. δ⁵⁶FeIRMM‐014 values of samples are ‐0.32‰ to ‐0.15‰, with an average of ‐0.20‰, which are consistent with those of the hydrothermal fluids previously reported. The narrow Fe isotope compositions of Cyprus umbers that are close to those of submarine hydrothermal fluids indicates near complete oxidation of hydrothermal Fe²⁺ during its expulsion from the hydrothermal vent.     

N and C Isotopic Compositions of the Lower Triassic of Southern Primorye and Reconstruction of Habitat Conditions of Marine Organisms after Mass Extinction at the End of the Permian

Data on the N and C isotopic composition are presented for the Lower Triassic claystones of the Abrek section of southern Primorye (Far East). The results showed five N isotopic intervals and several negative C isotopic excursions of the Induan–lower Olenekian stages of the Abrek section.     

大洋下地壳堆晶岩组成及其对蛇绿岩研究的启示

大洋下地壳是大洋岩石圈和蛇绿岩的重要组成部分,在洋中脊及俯冲带演化以及蛇绿岩成因研究中具有重要的意义。本文总结了不同构造环境形成的大洋下地壳堆晶岩的岩石组合、地球化学组成,以建立起适用于蛇绿岩中堆晶岩的构造环境判别标志。洋中脊和俯冲相关环境堆晶岩在Pearce图解上均区别于对应的熔岩成分,表明蛇绿岩中的堆晶岩无法应用Pearce图解进行构造环境判别。不同构造环境产出的堆晶岩在岩石组合、结晶顺序和地球化学上存在明显差异：(1)绝大多数洋中脊堆晶岩和弧后盆地堆晶岩较为类似,反映其来源于洋中脊玄武岩型母岩浆低压、贫水体系的分离结晶;(2)中大西洋脊DSDP 334的洋中脊堆晶岩较为类似弧前堆晶岩,是海水蚀变难熔橄榄岩重熔或混染的产物;(3)弧前堆晶岩的岩石学、地球化学特征与亏损的富水、富硅的玻安质熔体的低压分离结晶过程相吻合;(4)洋岛堆晶岩的特征与相对贫水、成分富集的洋岛玄武岩高压分离结晶的特征相吻合。最后,本文总结了应用堆晶岩进行蛇绿岩构造环境判别的一系列岩石学、地球化学指标,并结合日喀则蛇绿岩中的堆晶岩体和辉长岩脉的实例论述堆晶岩在蛇绿岩研究中的应用。

     

东濮凹陷构造变形的物理模拟研究

东濮凹陷是一个研究程度较高的含油气区,前人在构造变形研究方面多注重于伸展变形的几何学分析而忽略了形成机制中走滑分量的作用。本文在对区域地质背景和东濮凹陷构造特征分析基础上,设计平、剖面砂箱实验对该凹陷的构造变形进行伸展-走滑模拟研究。结果表明:(1)具走滑性质的断裂组合形成的构造样式更加复杂多样,走滑断层弯曲会产生挤压或伸展分量,在相邻的区域内形成局部的凹陷和隆起,主动盘的不同会形成不同的断裂组合;(2)在区域NNW—SSE向伸展变形下,形成了东濮凹陷两洼一凸的近对称格局,基底深断裂的张扭性开裂加速了凹陷的形成,主断层上、下盘均有明显的活动;(3)受基底断裂活动影响,大约Es~2-Ed沉积期凹陷存在一个明显的右旋走滑变形期,在凹陷的中部隆起带上出现了负花状、火焰状等典型走滑构造样式,走滑变形具有阵发性特点。     

Paragenetic Types and Compositions of Metamorphic Pyroxenes

Paragenetic types of pyroxenes, selected according to mineralassociations, differ in their average contents of the majorcations. By comparing with the average composition it is seenthat both the Fe/(Mg+Fe) ratio and the Fe⁺², Mn, Mg, Fe⁺³, andCr contents are determined in the main by the composition ofthe host rocks, but the AI_z, Al_y, Ca, and Na contents in pyroxenesare influenced by the conditions under which the rock was formed.The dependence of the Al_z and Al_y contents of orthopyroxenesand clinopyroxenes on temperature and pressure is shown withthe help of a new P-T diagram and by comparison with chemicalanalyses of natural pyroxenes. The correlation between the compound cations in pyroxenes isused to test the hypothesis of real isomorphous substitutionsin each paragenetic type of pyroxenes, and to determine rationalmethods of calculating pyroxene analyses into components. The calculated discriminant functions are useful for referring(with 5–10 per cent error) analyses of pyroxenes to oneof a number of paragenetic types, and in particular for distinguishingpyroxenes from magmatic and metamorphosed gabbros, and fromhigh- and low-temperature two-pyroxene granulites.     

Magnesium Isotope Compositions of Natural Reference Materials

This study presents a chemical protocol for the separation of Mg that is particularly adapted to alkali‐rich samples (granite, soil, plants). This protocol was based on a combination of two pre‐existing methods: transition metals were first removed from the sample using an AG‐MP1 anion‐exchange resin, followed by the separation of alkalis (Na, K) and bivalent cations (Ca²⁺, Mn²⁺ and Sr²⁺) using a AG50W‐X12 cation‐exchange resin. This procedure allowed Mg recovery of ～ 10 0 ± 8%. The [Σcations]/[Mg] molar ratios in all of the final Mg fractions were lower than 0.05. The Mg isotope ratios of eleven reference materials were analysed using two different MC‐ICP‐MS instruments (Isoprobe and Nu Plasma). The long‐term reproducibility, assessed by repeated measurements of Mg standard solutions and natural reference materials, was 0.14‰. The basalt (BE‐N), limestone (Cal‐S) and seawater (BCR‐403) reference materials analysed in this study yielded δ²⁶Mg mean values of ?0.28 ± 0.08‰, ?4.37 ± 0.11‰ and ?0.89 ± 0.10‰ respectively, in agreement with published data. The two continental rocks analysed, diorite (DR‐N) and granite (GA), yielded δ²⁶Mg mean values of ?0.50 ± 0.08‰ and ?0.75 ± 0.14‰, respectively. The weathering products, soil (TILL‐1) and river water (NIST SRM 1640), gave δ²⁶Mg values of ?0.40 ± 0.07‰ and ?1.27 ± 0.14‰, respectively. We also present, for the first time, the Mg isotope composition of bulk plant and organic matter. Rye flour (BCR‐381), sea lettuce (Ulva lactuva) (BCR‐279), natural hairgrass (Deschampsia flexuosa) and lichen (BCR‐482) reference materials gave δ²⁶Mg values of ?1.10 ± 0.14‰, ?0.90 ± 0.19‰, ?0.50 ± 0.22‰ and ?1.15 ± 0.27‰ respectively. Plant δ²⁶Mg values fell within the range defined by published data for chlorophylls.     

石英包裹体中液相成分的测定

文章简要介绍了石英包裹体样品的清洗、打开、成分的提取过程,列出采用离子色谱、原子吸收、感耦等离子体发射光谱、感耦等离子体质谱法测定液相各成分的流程及部分分析结果。     

Compositions of immiscible liquids in volcanic rocks

Immiscible liquids, preserved as chemically distinct, glassy globules, (Si-rich and Fe-rich) occur in many tholeiitic basalts and some alkaline and calcalkaline lavas. The glasses typically form part of a dark mesostasis containing skeletal magnetite crystals. In thick flows, the Si-rich liquid may crystallize to granophyric patches, and the Ferich one to aggregates of hedenbergite, magnetite, and accessory phases. The mesostases containing these immiscible phases constitute from 20% of a primitive olivine tholeiite (MgO=7.5%) to 50% of a highly fractionated quartz tholeiite (MgO=2.8%), but may be less if the rock is oxidized. Abundant ferric iron promotes early crystallization of magnetite and prevents the iron enrichment necessary to reach the immiscibility field; thus, aa flows rarely exhibit immiscibility, whereas the more reduced pahoehoe ones do.Alumina and alkalis are concentrated in the Si-rich liquid, whereas the remainder of the major elements are concentrated in the Fe-rich melt; but the partitioning of Fe, Mg, Ca, and P is less pronounced in alkaline rocks than in tholeiites. Conjugate liquids have compositions of granite and Fe-rich pyroxenite, though the Si-rich melt in alkaline rocks is more syenitic and the Fe-rich one contains considerable normative alkali feldspar. The liquids coexist with plagioclase and augite of, respectively, An₅₀ and Ca₃₄Mg₁₉Fe₄₇ compositions in tholeiites, and An₄₀ and Ca₄₂Mg₂₉Fe₂₉ in alkaline rocks. Immiscibility is not restricted to K-rich residual liquids, but the miscibility gap is narrower for Na-rich compositions. In tholeiitic basalts with 52% SiO₂, the Na₂O/K₂O ratios in conjugate liquids are equal, but at lower silica contents the Si-rich liquid is relatively more sodic, whereas at higher silica contents it is relatively more potassic. This may explain the association of sodic granites with mid ocean ridge basalts.Immiscible liquids are present in sufficient amounts in so many volcanic rocks that magma unmixing should be considered a viable means of differentiation during the late stages of fractionation of common magmas, at least at low pressures.     

Barium Isotopic Compositions of Geological Reference Materials

The interest in variations of barium (Ba) stable isotope amount ratios in low and high temperature environments has increased over the past several years. Characterisation of Ba isotope ratios of widely available reference materials is now required to validate analytical procedures and to allow comparison of data obtained by different laboratories. We present new Ba isotope amount ratio data for twelve geological reference materials with silicate (AGV‐1, G‐2, BHVO‐1, QLO‐1, BIR‐1, JG‐1a, JB‐1a, JR‐1 and JA‐1), carbonate (IAEA‐CO‐9) and sulfate matrices (IAEA‐SO‐5 and IAEA‐SO‐6) relative to NIST SRM 3104a. In addition, two artificially fractionated in‐house reference materials BaBe12 and BaBe27 (δ^137/134Ba = ?1.161 ± 0.049‰ and ?0.616 ± 0.050‰, respectively) are used as quality control solutions for the negative δ‐range. Accuracy of our data was assessed by interlaboratory comparison between the University of Bern and the United States Geological Survey (USGS). Data were measured by MC‐ICP‐MS (Bern) and TIMS (USGS) using two different double spikes for mass bias correction (¹³⁰Ba–¹³⁵Ba and ¹³²Ba–¹³⁶Ba, respectively). MC‐ICP‐MS measurements were further tested for isobaric and non‐spectral matrix effects by a number of common matrix elements. The results are in excellent agreement and suggest data accuracy.     

Compositions of Upper Mantle Fluids Beneath Eastern China: Implications for Mantle Evolution

The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in Iherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 a