二连盆地乌兰花凹陷烃源灶表征及其对油气分布的控制

乌兰花凹陷是近年来在二连盆地南部新发现的富油凹陷,但南北两个洼槽探明的油气资源差异明显。为了准确评价乌兰花凹陷的油气资源潜力,系统地分析了乌兰花凹陷烃源灶特征,讨论了烃源灶与油藏分布的关系。研究表明,乌兰花凹陷阿尔善组至腾一上段发育C、D/E和F相源岩,受构造-层序演化的影响,南北洼槽倾油型(C相)源岩发育层段存在明显差异,南洼槽C相源岩主要发育在阿尔善组,腾一上段和下段以D/E相源岩为主,而北洼槽阿尔善组至腾一上段均发育C相源岩。多口探井热史标定结果表明,乌兰花凹陷烃源岩成熟门限在2000 m左右,南洼槽仅阿尔善组烃源岩进入成熟阶段,阿尔善组C相源岩排油强度为0.5～7.9MMT/km2,为凹陷的主力烃源岩,而北洼槽阿尔善组C相烃源岩主要发育在阿尔善组上段,成熟度较低,最大值仅为0.78%Ro,烃源灶排烃强度小于0.2 MMT/km2,不能形成规模性的油藏。乌兰花凹陷探明的原油均在南洼槽,且集中在烃源灶周围,表现为近源聚集。     

Influences of fisheries management measures on biological characteristics of threadfin bream (Nemipterus virgatus) in the Beibu Gulf,South China Sea

Long-term variations in population structure, growth, mortality, length at median sexual maturity, and exploitation rate of threadfin bream (Nemipterus virgatus) are reported based on bottom trawl survey data collected during 1960–2012 in the Beibu Gulf, South China Sea. Laboratory-based analyses were conducted on 16791 individuals collected quarterly in eight different sampling years. Average body length, estimated asymptotic length, and percentage of large individuals have decreased significantly with the growth of marine catch and fishing power, indicating individual miniaturization of this fish species. Estimated exploitation rates indicate that the N. virgatus stock in the Beibu Gulf was moderately exploited in 1960 and 1962 and overexploited after 1992. This stock was taking a good turn in status in 2012, with the lowest exploitation rate since 1992 and ceased downward trend in length indexes. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of this commercial fish species. Biological characteristics of most commercial fish species have phenotypic plasticity and might change over years in response to fisheries management. Therefore, attentions should be paid on variations in fish biological characteristics, when evaluating the effectiveness of current measures to control the total catch for all fisheries.     

Study on the geochemical correlation of crude oils of Palaeocene and Jurassic ages from the Potowar Indus Basin in northern Pakistan

This study deals with a detailed geochemical characterization of three crude oils from the Upper Indus Basin, Punjab, Pakistan. The samples were obtained from three productive oil fields of the Datta Formation (Jurassic), Lochhart (Palaeocene) and the Dhak Pass zone (Palaeocene). The GC parameters for and the bulk properties of Datta Formation oils are essentially coincident with those of the oils from the Dhak Pass Formation in the Upper Indus Basin, Pakistan and the oils likely originate from a marine source rock. In contrast, the Lockhart Formation oils show different behaviors and seem to be originated from dirty carbonate rocks although all three crude oils are mature, being of non-biodegraded and somewhat mixed organic matter origin. Low Pr/Ph values and high C₃₅ homohopane index for the Lockhart Formation oils suggest a source of anoxic environment with low Eh while oils from the Datta Formation and Dhak Pass Formation showed different trends, i.e., lower values of C₃₅ homohopane index indicating different depositional environment than oil from the Lockhart Formation. All three crude oils from the Upper Indus Basin are mature for the hopane ratios, i.e., Ts/Ts+Tm, C₃₂22S/(S+R) and C₃₀ αβ/(αβ+βα) and sterane ratios, i.e., C₂₉22S/(S+R) and C₂₉ββ/(ββ+αα) but oils from the Lockhart Formation seem to be less mature than those from the Palaeocene and Datta Formation according to plots like API° vs. homohopane Index, Pr/Ph vs. sterane. The relative composition of 5α(H), 14β(H), 17β(H)-24-ethylecholestanes and the C₂₉20S/20S+20R index, indicate that all three crude oils are equally mature, which makes it unlikely with respect to the above said plots. This difference is may be due to the migratory chromatography which alters the concentrations of sterane and hoapnes and hence gives different results. These oils do not exhibit UCM and have complete n-alkane profiles indicating non-biodegradation.     

准噶尔盆地东缘晚石炭世花岗岩岩石地球化学特征及铀成矿潜力分析

准噶尔盆地东缘将军庙北部花岗岩岩石地球化学特征、稀土元素、微量元素及Sr-Nd-Pb同位素特征显示,该花岗岩形成于碰撞后期板内裂谷环境,其源区主要为软流圈地幔,同时有上地壳物质的混染。初步判定准噶尔盆地东部将军庙地区晚古生代构造环境为成熟岛弧环境,略高于准噶尔盆地平均水平。该地区不同构造单元的古生代大地构造背景及其地壳成熟度存在较大的差异,地壳成熟度整体较低,在一定程度上制约了该区砂岩型铀成矿作用的发育规模。     

估算天然气成熟度的新指标--金刚烷指标

采用天然气重烃富集及MID/GC/MS分析技术,从天然气中检测出单、双金刚烷类化合物。根据琼东南盆地生油岩中金刚烷指标 (Ⅱ )与镜煤反射率 (Ro)的实测值,结合应用塔里木盆地、鄂尔多斯盆地的上述实测数据点,建立了双金刚烷指标与镜煤反射率 (Ro)数值对应关系。根据这种关系成功地确定和研究了莺-琼盆地三个构造天然气的成熟度。研究成果不仅提供了检测天然气中金刚烷类化合物的方法,扩大了金刚烷类化合物的应用范围,而且表明金刚烷类化合物是研究天然气成熟度的一个有效指标     

准噶尔盆地西北缘车排子地区侏罗系物源及古水流分析

通过岩石岩屑组分分析、重矿物组分分析、倾角测井、地层厚度分析等方法，对准噶尔盆地西北缘车排子地区侏罗系进行物源及古水流方向分析。岩屑组分分析指示着大致的物源前进方向，重矿物分析明确了物源泄入的主要通道，倾角测井在单井点处对古流向有相当高的表现精度，但这三种方法均存在数据平面覆盖率较低和分布密度差异大的缺陷，而运用地震层位解释所得的地层等厚度图则可以在较大尺度上的二维平面内推测沉积时期的古地形，进而可以推测古流向，但它仅是一种间接预测方法，存在局部古流向预测精度较低的不足。文中综合各种方法，将直接预测方法的高精度和间接方法的高覆盖能力结合起来，对古流向作出较高精度的预测。在古流向研究的基础上建立了冲积扇－辫状河－河泛平原沉积体系的沉积相模式。该模式认为对于水流能量保持能力差的冲积扇，其古流向应该沿短轴陡坡降方向，即大致为SEE方向，而对于水流能量保持能力较强的辫状河来说，其古流向应该沿长轴缓坡降方向，即为SE甚至SSE方向。该模式的提出对于提高地震相－沉积相的转相精度具有一定的指导意义。     

The trophic ecology of arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) in Ellidavatn, a small lake in Southwest Iceland

In the lake Ellidavatn, southwest Iceland, fish samples were collected with gillnets of one mesh-size once or twice a month for two years. Stomach samples of 961 Arctic char and 429 brown trout were analysed. The annual diet of char consisted of chironomid larvae (31%), cladocerans Eurycercus lamellatus (19%), bivalves Pisidium spp. (16%), water snails Lymnaea peregra (15%), chironomid pupae (8%) and char eggs (5%) and that of trout consisted of sticklebacks (76%), salmonids (7%) and L. peregra (6%). The average percentage of indigestible plant remains and gravel in the stomach content was much higher for the char (14%) than trout (3%). There were large seasonal changes in the diet of char: char eggs were consumed in autumn, chironomid larvae mostly from autumn to spring, chironomid pupae in summer and E. lamellatus from summer to autumn. No seasonal changes in the diet of trout were seen. The diet overlap of char and trout was very low, usually about 10%, reaching a maximum of about 30% in late summer 1976 when the common diet was mainly E. lamellatus and chironomid pupae. The resource partitioning in Ellidavatn indicates that char are better adapted to preying on small benthic invertebrates than piscivorous trout. The segregation in the diet of the two species indicated competition for restricted food supply, which was also consistent with slow growth and low condition factor of char (0.8–1.0) and trout (1.0) in Ellidavatn. The prey of trout were two orders of magnitude larger than the prey of char which may explain why adult char grew more slowly (2 cm y⁻¹) than adult trout (4 cm y⁻¹) and reached sexual maturity at a smaller size (30 cm) than trout (40 cm).     

新疆主要造山带地壳发展的五阶段模式及成矿系列

按汉尼克（１９８１）提出的简单剪切模式，大陆解离是沿一条缓倾斜的拆离带发生移离。随着拆离的发展，上地慢软流圈隆起追随拆离面下降的一侧迁移，而始终处于解离大陆一侧边缘的下方（而不是在拉伸洋盆的中线上）。因此，在有上地幔软流圈隆起对应的陆缘一侧，会产生大量火山—深成岩浆作用（主要是上地幔物质的渗入），称为“岩浆型被动陆缘”（旧称“火山型被动陆缘”）；而另一侧，则仅表现为地壳表层的构造破坏和陆源碎屑堆积作用，即经典意义上的大西洋型被动陆缘，称为“非岩浆型被动陆缘”。裂谷一般地可看成是上述解离过程初期阶段的产物。上述过程的几种构造环境下的地壳，都具有厚度减小、地壳渗透性增加、成熟度降低的特点，称为“拉张型过渡壳”。拉张型过渡壳阶段是陆同型造山带地壳发展中必不可少的阶段。它的标志性建造是双峰式火山岩建造（岩浆型被动陆缘）和巨厚陆源碎屑岩夹基性火山岩建造（非岩浆型被动陆缘），建造序列由稳定性类型向非稳定性类型演化，地球化学表现出成熟度不断降低的趋势。当基底陆壳拉伸减薄至零时，出现洋壳，洋壳阶段的产物为蛇绿岩建造。当扩张终止，洋盆开始消减，两侧陆缘演化即进入“汇聚型过渡壳阶段”。在汇聚阶段中，前两阶段形成的产物被强烈堆挤     

关于碳酸盐源岩研究的两个问题

简要介绍了碳酸盐源岩研究中的两个问题:有机质的赋存状态(分散且不均一)及确立成熟度的新指标透射色指数(TCI)的最新进展。     

轮南油田原油中三甲基苯基类异戊二烯化合物的检出及其意义

轮南油田不同时代储层原油中检出了丰富的三甲基苯基类异戊二烯化合物。该类化合物被普遍认为是来自于高盐度和强还原水体沉积环境中绿硫菌体内的类胡萝卜素的特征性生物标志化合物。该类化合物的检出对轮南油田烃源岩研究具有重要的指示意义，暗示了具有分层水体或高盐度的强还原环境下发育的优势烃源岩，对该区烃类的主力生烃贡献不容忽视。基于C15-3，4，5-三甲基苯基类异戊二烯异构体在轮南油田原油中的分布规律，及C15-3，4，5／C13-2，3，6-比值与Pr／Ph，Ga／C31H和Ts／Tm等常规地球化学参数的对比，说明具有生源意义、能够指示沉积相特征的三甲基苯基类异戊二烯化合物分布，在一定程度上也受烃类热演化程度的影响。