东海盆地西湖凹陷油岩地球化学特征及原油成因来源

东海盆地西湖凹陷具有大量的原油资源,但对于原油成因讨论较少.采集西湖凹陷多个油样和岩样,利用气相色谱和傅里叶红外光谱等手段,全面分析了该区烃源岩和原油的地球化学特征,综合讨论了原油来源以及凝析油和高蜡轻质油的成因.研究结果表明,平湖组煤系源岩均处于热演化的成熟阶段,其中碳质泥岩和煤岩以陆源生物为主要生源,其干酪根类型为Ⅲ型,暗色泥岩则具有陆源生物和水生生物双重生源贡献,其干酪根类型Ⅱ-Ⅲ型,同时碳质泥岩和煤的生油潜力远高于泥岩.原油主要为凝析油和轻质油,凝析油具有低密度、低蜡等“六低一高”的特点,轻质油具有高蜡特质,而且轻烃组分有明显差异.生标参数显示大部分原油为腐殖型,少部分原油表现出具有腐殖和腐泥母质的特点,同时该区原油均处于中等成熟阶段.油油对比和油岩对比表明大部分油来自平湖组碳质泥岩和煤岩,具有典型Ⅲ型腐殖油的特征;少部分油来自暗色泥岩,具有Ⅱ-Ⅲ型油的特征(总体上仍偏腐殖型).凝析油和轻质油的物性及轻烃组分的差异与源岩母质无关.凝析油是干酪根在成熟演化阶段生成的原油遭受蒸发分馏作用的结果,高蜡轻质油除了是“蒸发分馏作用”的残余油外,还有部分是“混合作用”的结果.      

新疆哈密土屋铜矿床地质和地球化学特征

土屋铜矿床是我国近年来发现的特大型斑岩铜矿床,其独特矿床地质背景和矿床规模已经引起国内外地质学界和矿业界的广泛关注;本文详细叙述该矿床的地质背景,对矿床的地质、地球化学特征进行系统研究和总结,对矿床的成矿作用动力学过程进行探讨。研究表明,该矿床成矿物质具有深部来源特征,而岩浆在侵位过程中受到上地壳物质一定程度的混染;成矿流体以岩浆水为主,天水和岩浆水的混合仅为少量;石英流体包裹体均一温度较低,但盐度较高;含矿斑岩体是多次脉动式侵位的,成岩时代主要集中于早石炭世(367～358 Ma);成矿时代为晚于成岩时代(347.3±2.1 Ma～322.7±3 Ma)。     

赣南地区石英脉型钨矿成矿流体特征

赣南是我国钨矿床最密集的地区,尤以石英脉型钨矿最为发育.本文通过分析近年来该区石英脉型钨矿流体包裹体类型、流体包裹体特征、显微测温、激光拉曼光谱等方面的最新成果,结合碳、氢、氧及锶同位素的研究成果,探讨赣南石英脉型钨矿的流体特征,重点探讨石英脉型钨矿形成过程中的流体演化.认为赣南石英脉型钨矿成矿流体主要来源于岩浆水,流体演化始于高温高盐度的岩浆—热液过渡阶段,与黑钨矿沉淀密切相关的流体温度主要集中于260~360℃,盐度主要集中于4~9 wt% NaCl eq.,属中—低盐度、富含SiO2、挥发组分及多种成矿元素的热液体系;矿质主要以流体沸腾和混合作用为主,自然冷却仅为少数矿床的主要矿石沉淀机制.     

Impacts of environmental flow controls on the water table and groundwater chemistry in the Ejina Delta,northwestern China

The impacts of environmental flow controls on the water table and chemistry of groundwater in the Ejina Delta, an arid inland river basin in northwest China, were investigated with field observations in 2001 and 2009. The results indicate that the shallow groundwater level rose by 0–2 m in the upper reaches of the east tributary of the Heihe River and in the areas of Saihantaolai—Dalaikubu during the period of environmental flow controls. The chemical constituents of the groundwater show a distinct spatial heterogeneity with the total dissolved solids (TDS) in the groundwater increasing from the periphery towards the depocenter of the Ejina Basin. In addition, the rate of groundwater cycling in the south of the Ejina Delta increased, and the mineralization of groundwater declined, while the overall mineralization and salinity increased in the northern regions, especially in the depocenter of the Ejina Basin. Since shallow groundwater is important to the ecology of arid regions, and because understanding the changes in the shallow groundwater environment (groundwater level and hydrochemistry) in response to environmental flow controls is essential for the sustainable improvement of the ecological environment, the results of this paper can be used as a reference for watershed water resources planning and management to help maintain the health and proper function of rivers in arid regions.     

Cold subduction of the Neotethys: the metamorphic record from finely banded lawsonite and epidote blueschists and associated metabasalts of the Nagaland Ophiolite Complex,India

In this study, we have deduced the thermal history of the subducting Neotethys from its eastern margin, using a suite of partially hydrated metabasalts from a segment of the Nagaland Ophiolite Complex (NOC), India. Located along the eastern extension of the Indus‐Tsangpo suture zone (ITSZ), the N–S‐trending NOC lies between the Indian and Burmese plates. The metabasalts, encased within a serpentinitic mélange, preserve a tectonically disturbed metamorphic sequence, which from west to east is greenschist (GS), pumpellyite–diopside (PD) and blueschist (BS) facies. Metabasalts in all the three metamorphic facies record prograde metamorphic overprints directly on primary igneous textures and igneous augite. In the BS facies unit, the metabasalts interbedded with marble show centimetre‐ to metre‐scale interlayering of lawsonite blueschist (LBS) and epidote blueschist (EBS). Prograde HP/LT metamorphism stabilized lawsonite + omphacite (X_Jd = 0.50–0.56 to 0.26–0.37) + jadeite (X_Jd = 0.67–0.79) + augite + ferroglaucophane + high‐Si phengite (Si = 3.6–3.65 atoms per formula unit, a.p.f.u.) + chlorite + titanite + quartz in LBS and lawsonite + glaucophane/ferroglaucophane ± epidote ± omphacite (X_Jd = 0.34) + chlorite + phengite (Si = 3.5 a.p.f.u.) + titanite + quartz in EBS at the metamorphic peak. Retrograde alteration, which was pervasive in the EBS, produced a sequence of mineral assemblages from omphacite and lawsonite‐absent, epidote + glaucophane/ferroglaucophane + chlorite + phengite + titanite + quartz through albite + chlorite + glaucophane to lawsonite + albite + high‐Si phengite (Si = 3.6–3.7 a.p.f.u.) + glaucophane + epidote + quartz. In the PD facies metabasalts, the peak mineral assemblage, pumpellyite + chlorite + titanite + phengitic white mica (Si = 3.4–3.5 a.p.f.u.) + diopside appeared in the basaltic groundmass from reacting titaniferous augite and low‐Si phengite, with prehnite additionally producing pumpellyite in early vein domains. In the GS facies metabasalts, incomplete hydration of augite produced albite + epidote + actinolite + chlorite + titanite + phengite + augite mineral assemblage. Based on calculated T–M(H₂O), T–M(O₂) (where M represents oxide mol.%) and P–T pseudosections, peak P–T conditions of LBS are estimated at ~11.5 kbar and ~340 °C, EBS at ~10 kbar, 325 °C and PD facies at ~6 kbar, 335 °C. Reconstructed metamorphic reaction pathways integrated with the results of P–T pseudosection modelling define a near‐complete, hairpin, clockwise P–T loop for the BS and a prograde P–T path with a steep dP/dT for the PD facies rocks. Apparent low thermal gradient of 8 °C km^?1 corresponding to a maximum burial depth of 40 km and the hairpin P–T trajectory together suggest a cold and mature stage of an intra‐oceanic subduction zone setting for the Nagaland blueschists. The metamorphic constraints established above when combined with petrological findings from the ophiolitic massifs along the whole ITSZ suggest that intra‐oceanic subduction systems within the Neotethys between India and the Lhasa terrane/the Karakoram microcontinent were also active towards east between Indian and Burmese plates.     

构造附加动力对煤变质过程的影响

本文从固体力学、构造物理化学的角度分析了煤岩所受应力的来源、性质以及应力在煤变质过程中的影响方式。作者在前人研究基础上,阐述了构造动力影响过程中煤岩能量的转换形式,分析了应力在烟煤分子团聚过程中的影响。研究认为,煤岩所受的各种应力(压应力、拉应力、剪应力)为地层压力与构造动力所造成的附加内力。这种附加内力可以分解为构造附加静水压力与偏应力两部分。构造附加静水压力主要影响煤岩的物理性质,如孔隙度、颗粒性质与瓦斯吸附特征,并对煤的化学煤化过程有缓慢促进作用。偏应力主要使煤岩发生变形和位移。煤化过程中,由构造运动所产生的动能转化为各种形式的热能、表面能、弹性变形能以及声、光、电、磁等形态能量。     

西藏嘎拉勒夕卡岩型铜金矿白云母~(40)Ar-~(39)Ar年龄及其地质意义

西藏嘎拉勒夕卡岩型铜金矿床中铜的资源量达到中型规模,金的资源量达到大型规模。在系统的野外地质调查基础上,选取矿床夕卡岩中保存极好的白云母,测得40Ar-39Ar年龄为91.48Ma±0.68Ma,代表矿床成矿年龄,表明矿床为燕山运动晚期的产物。结合区域地质资料认为,在拉萨地块中北部,成矿年龄约为90Ma的夕卡岩型—斑岩型矿床集中分布在措勤—申扎岩浆弧上;在早白垩世班公湖—怒江洋盆闭合后,狮泉河—永珠—纳木错—嘉黎蛇绿混杂带(Slainajap带)上的弧后盆地和弧间盆地演化成了一系列小洋盆,这些小洋盆的演化与中拉萨地块北部成矿年龄约为90Ma的夕卡岩—斑岩型矿床的形成有更直接的关系。今后宜加大在措勤—申扎岩浆弧上寻找成矿年龄约为90Ma的夕卡岩—斑岩型矿床的力度。     

俄罗斯贝辰加镍-铜硫化物矿床研究进展

贝辰加镍-铜硫化物矿床位于俄罗斯北极圈内科拉半岛西北部,是一个世界级镍-铜矿集区。矿集区目前共发现25个含工业矿体的侵入体,分东、西2个矿带,已探明镍资源量470×104t,品位1.2%,铜储量350×104t,品位0.9%,与俄罗斯诺里尔斯克、加拿大萨德伯里、中国金川等矿床并列为世界级大型铜镍硫化物矿床。贝辰加杂岩体由4套古元古代火山-沉积旋回构成,含矿的为第四套火山-沉积旋回皮尔咖加维建造。矿集区内的火山-沉积作用发生在1940~2500Ma之间,成矿作用发生在1950~1990Ma之间,矿化作用发生在古元古代该地区岩浆演化的晚期阶段。贝辰加镍-铜矿赋矿岩石为富铁苦橄岩,具有高铁、低Al2O3,高TiO2、Zr和其他不相容元素的特点,强烈富集LREE,地球化学特征类似于板内玄武岩或碱性玄武岩。矿床成矿模式为地幔柱分支分异成的贝辰加岩体侵入裂陷槽,其西部矿体侵入至沉积地层之上,东部矿体侵入到沉积地层内部。硫通过岩浆侵位过程中的同化作用进入岩浆,形成硫化物熔融体,并在后期经历了构造变形、热液叠加等作用后形成了浸染状、角砾状等多种类型的矿化。     

Development of Synthetic Clinopyroxene Reference Materials for In Situ Lithium Isotope Measurement by LA-MC-ICP-MS

The isotopic composition of lithium (Li) in clinopyroxene (Cpx), determined via in situ micro-analysis, has been employed as a potential geochemical tool for studying various geological processes such as crust-mantle recycling, silicate weathering and fluid-rock interaction. To obtain precise and accurate Li isotopic compositions in Cpx by LA-MC-ICP-MS, synthetic Cpx matrix-matched reference materials (RMs) were prepared in this study. Six Cpx-matrix RMs were prepared by mixing metallic oxides with GSP-2 (granodiorite) or pure L-SVEC solution and melting them into glasses (GSP-2 + oxide; L-SVEC + oxide). Two representative synthetic glasses, CPXA01 and CPXB01, were subjected to a series of analyses to investigate the possible qualification of the RMs for in situ Li isotope measurement by LA-MC-ICP-MS, including elemental homogeneity analysis (elemental mapping analysis and spot analysis), Li isotopic homogeneity analysis and accurate Li isotopic determination. The applicability of the synthetic Cpx-matrix RMs was highlighted by comparing the δ⁷Li values of three natural Cpx calibrated against the synthetic Cpx-matrix RMs and other commonly used RMs with different matrices (NIST SRM 612, BCR-2G, GOR128-G, StHs6/80-G, KL2-G and T1-G), respectively. Additionally, CPXB01-05 RMs with the same matrix but different Li contents were prepared to explore the Li content mismatch effect, which is significant for accurate determination of in situ Li isotopic composition by LA-MC-ICP-MS. The results of the cross-calibration of Li isotopes in CPXA01 and CPXB01 suggested no obvious Li isotopic fractionation between the two types of glasses (GSP-2 + oxide; L-SVEC + oxide). Thus, the two methods of producing Cpx-matrix RMs are suitable for preparing the matrix-matched RMs for in situ microanalysis for Li isotopes.     

Bootstrap aggregating approach to short-term load forecasting using meteorological parameters for demand side management in the North-Eastern Region of India

Theoretical and Applied Climatology - Electricity is an essential commodity that must be generated in response to demand. Hydroelectric power plants, fossil fuels, nuclear energy, and wind energy...