湖北清江和尚洞洞顶植物叶片和土壤的类脂物对比及其意义

用GC-MS对湖北清江岩溶地区和尚洞洞顶植物叶片与该洞上覆土壤层中的类脂物进行了分析和对比。在植物叶片中检测出了一系列直链烷烃、脂肪酸、以及丙三醇、植醇和甾醇等类脂物,其中直链烷烃的碳数分布范围大体在C21～C36之间,以C29或C31为主峰且具有奇偶优势;脂肪酸的分布主要集中在中、短链脂肪酸内（C数<23）,以C16为主峰呈单峰型分布且具有偶奇优势;醇的分布很不规则,仅检测出丙三醇,植醇和三种甾醇,没有检测到脂肪酮类化合物。与之相比,洞顶上覆土壤层中检测出更加丰富的类脂物。类脂物具有如下特征:正构烷烃以C31为主峰,还存在低碳数正构烷烃和异构烷烃,如2-甲基、3-甲基、4-甲基、5-甲基、6-甲基、7-甲基、8-甲基等一系列的单甲基支链烷烃,这些支链烷烃显示了微生物的贡献;脂肪酸分布也以低碳数的C16为主峰,且低碳数脂肪酸的含量较植物叶片中明显的增加,同时一些异构和反异构脂肪酸（C14∶0,C15∶0和C17∶0）以及一些单不饱和脂肪酸（C16∶1,C17∶1,C18∶1和C20∶1）也被检测到,也表明土壤中的脂肪酸不仅存在高等植物的贡献,还存在微生物的来源;没有植醇,但出现姥鲛烷和植烷并检测到了一系列脂肪醇化合物,碳数分布在C21～C36之间;检测到一系列的酮,具有奇偶优势,碳数分布范围在C23～C30和C33。高等植物叶片和土壤的差异反映了微生物对高等植物类脂物输入到土壤过程的重要贡献。本研究工作不仅提供了该岩溶地区植物叶片的类脂物信息,还为研究土壤有机质的来源和植物叶片中类脂物在地质过程中的转变提供信息,更为研究岩溶地区滴水和石笋中类脂物的来源提供一定的参考。     

滇池湖泊沉积物中游离类脂物的有机地球化学特征

在对滇池湖泊沉积物有机质总体特征分析的基础上,对沉积物中可溶性有机质的组成进行了定量测定,并揭示了其剖面变化特征.研究结果表明:(1)正构烷烃组分具有较强的稳定性,反映出滇池沉积有机质以菌藻类来源为主,沉积柱上、下两段存在陆源高等植物输入相对增加的特征,且从下往上存在草本植物相对贡献增加的特征;(2)脂肪醇组分,以具有强烈偶碳优势的高碳数脂肪醇为主,反映了沉积有机质中陆源输入的部分;(3)脂肪酸组分揭示出可溶有机质中以浮游植物贡献为主,局部层段存在相对较强的细菌改造作用.因此,湖泊沉积物记录了滇池从一个贫营养的湖泊演变成富营养化湖泊的过程,特别是最近几十年,滇池内源有机物和陆源有机物的输入都呈现快速增长的趋势,结合同位素组成特征表明滇池进入了重富营养化阶段.     

湖北清江和尚洞洞穴滴水脂肪酸分布特征及其古生态意义

对采自湖北省清江和尚洞滴水样品,采用XAD大孔径树脂吸附法及气相色谱-质谱联用仪(GC-MS)检测出种类丰富的脂肪酸,包括直链(nC12:0～nC30:0)与支链(iC14:0～iC26:0,及aC15:0和aC17:0)饱和脂肪酸,直链单不饱和脂肪酸(nC15:1,nC16:1,nC17:1和nC18:1),多不饱和脂肪酸(nC18:2)及微量的支链不饱和脂肪酸(iC17:1).滴水脂肪酸分布特征显示有机质以微生物来源为主,兼有高等植物贡献.占优势的偶碳直链饱和脂肪酸(主要是nC16:0,nC18:0和nC14:0),含量相对较高的单不饱和脂肪酸及多不饱和脂肪酸可能主要来源于地下水微藻.滴水中还检出含量较高的nC17:1和nC15:1及微量的iC17:1和iC15:1,它们很可能来自洞顶土壤厌氧层中的硫酸盐还原菌.洞顶土壤、滴水与现代石笋碳酸钙沉积脂肪酸分布对比揭示,石笋有机质主要来源于土壤,也有地下水微生物及洞穴原地微生物贡献.     

察尔汗盐湖正构烷烃和单体碳同位素分布特征及其古植被意义

对察尔汗盐湖ISL1A钻孔沉积物样品进行了有机分子地球化学分析, 检测出了丰富的类脂物, 包括正构烷烃、一元正脂肪酸、一元正脂肪醇等, 本文主要讨论正构烷烃类脂物的分布特征。正构烷烃的分布型式表明其来源于低等菌藻类生物和陆生高等植物, 正构烷烃的高碳数部分均有显著的奇偶优势, 高碳数正构烷烃全部以C31 为主峰碳。正构烷烃分布特征表明在110.1~50.1 ka B.P.期间, 察尔汗盐湖地区为草原植被景观。对C27、C29、C31 长链正构烷烃进行了单体碳同位素测定, 利用二元模式估算了C3 和 C4 植物的相对输入贡献, 结果表明, 以C3 植物为主。     

南海沉积物中的黏土矿物:指示东亚季风演化历史?

黏土矿物以其示踪洋流变化和揭示物源区同时期气候变化的能力,近年来在南海沉积古环境研究中的地位日益显现。但是,南海黏土矿物能否用于直接指示东亚季风演化历史的研究仍然颇为争议。本研究认为,南海黏土矿物主要受控于物源区供给和洋流搬运作用,黏土矿物本身不具同时期气候条件特征。以南海北部为例,珠江、台湾和吕宋岛这三个主要物源区无论是冰期还是间冰期都提供相同的黏土矿物组合,这些黏土矿物在输入到南海后分别受到不同洋流的搬运。因此,南海晚第四纪黏土矿物组合用于指示东亚季风演化历史的应用是通过洋流的搬运作用来实现的,在不同海区的应用效果不同。     

南海表层沉积物中生物钡的分布特征及其与初级生产力的关系

分析了南海东部53个站位表层沉积物中生物钡、铝以及有机碳和生物硅等生源物质的分布特征。结果表明,南海东部表层沉积物中的有机碳含量在研究区的北部陆架区出现高值,而在吕宋岛以西的深海则最低;生物硅的平面分布则表现为在吕宋岛以西的深海低沉积速率区出现高值,而低值则出现在高沉积速率的北部海域;生物钡的平面分布与生物硅的分布特征相似,高值出现在吕宋岛以西的深海区,且表现出自北而南沉积物中生物钡的含量逐渐增加的趋势。研究区内初级生产力表现为从北向南增加的趋势,而沉积物中生物钡的含量也呈现相似的趋势,表明沉积物中生物钡的含量和上层水体的生产力有一定的相关性。但表层沉积物中生物钡与有机碳呈弱的负相关关系,而与生物硅显著相关,且生物钡和生物硅与水深的相关性均呈现显著的相关性。因此,在采用沉积物中生物钡含量研究南海上层水体初级生产力时应谨慎对待。     

南海北部古俯冲带的位置及其对南海扩张的控制

为了确定南海北部古俯冲带的具体位置,作者利用美国LCT综合反演软件对收集到的重磁数据进行处理解释,结果显示在南海北部从台湾西南部到一统暗沙隆起,即沿南海海盆北部陆坡为一条布格重力异常水平梯度峰值带,指示了古俯冲带的具体位置;其北部的高磁异常代表了与之对应的古火山弧。深反射地震资料也验证了南海北部陆坡位置存在古俯冲带,钻井资料显示俯冲带存在的时代为晚侏罗世到早白垩世。据此绘制了南海地区晚中生代到现今的构造古地理演化图,指出南海的扩张应与晚中生代俯冲带这个先存的软弱带有关,南海海盆正是从古俯冲带的位置开始扩张。     

岩溶地区现代土壤与洞穴石笋中单甲基支链烷烃与烷基环己烷对比研究

利用GC-MS（气相色谱—质谱仪）,对采自湖北清江流域和尚洞洞顶的土壤样品与洞内石笋样品进行分析,发现土壤中存在的七个系列单甲基支链烷烃在所有的石笋样品中均可以找到,呈现相似的分布模式,石笋中七个系列支链烷烃有可能来自洞穴滴水携带的土壤中的支链烷烃,但是也不能排除石笋原地生长的微生物的贡献。烷基环己烷的分布在土壤与石笋中呈现了相似的分布模式,但是主峰碳数有所变化,高碳数部分与低碳数部分的相对含量也发生了变化。主要原因可能是微生物选择性降解的结果,也有可能是土壤与石笋中微生物种类分布差异所造成的。本次研究初步显示了相对封闭稳定的洞穴沉积物与上覆土壤层中生物标志化合物的异同。      

南海表层沉积物的稀土和微量元素的丰度及其空间变化

对南海表层沉积物中稀土元素、微量元素丰度和分布特征的研究结果表明,在空间分布上,∑REE与Nb、,Th、Ta、Rb、Ti、Zr、Hf、Cs、Ga、Li等相似,呈显著正相关,反映出这些元素在风化、搬运和沉积过程中地球化学行为非常相似;元素Sr几乎与所有元素都呈负相关,指示其来源或存在形式不同于其他元素,主要来源于生物作用,而在粗粒级的钙质生物贝壳和碎屑中富集.∑REE与Nb、Th、Ta、Rb、Ti、Zr、Hf、Cs、Ga、Li在陆架区具有沿陆分带特点,北部陆架区、中南半岛中东部和加里曼丹岛西北部沿大陆区域富集,与该区陆源河流物质输入及海流的分选作用,造成某些富含稀土和微量元素的重砂矿的富集有关;西南部巽他陆架和东南部岛礁区以及中、西沙附近区域含量较低,与该区域的生源碳酸盐的稀释作用,使粘土矿物相对减少和火山物质对其产生的“稀释“作用有关.南海各海区沉积物和全海区表层沉积物平均值的球粒陨石标准化稀土元素分布模式,总体上与中国大陆沉积物和浅海沉积物相似,而与大洋玄武岩完全不同,反映了南海沉积物与中国浅海沉积物及中国大陆沉积物的物源大致相同,主要来自陆源.南海各海区沉积物稀土元素的球粒陨石标准化配分曲线仍表现出了一定差异,陆架区轻稀土比重稀土明显富集,存在比较明显的Eu负异常,与陆架区相比较,陆坡区和海盆区则轻稀土含量相对降低,重稀土含量有所上升,LREE/HREE从陆架区、陆坡区到海盆区逐渐降低,显示陆架区主要为陆源,而陆坡和海盆沉积物中则有幔源物质加入.稀土元素的大陆壳标准化配分模式大部分较为平坦,少数样品呈轻稀土弱富集型或重稀土弱富集型.说明南海海表层沉积物主要来源于周边大陆.从各海区沉积物稀土元素的大陆壳标准化配分曲线对比来看,陆架区表现为轻稀土富集、重稀土亏损,具一定的铕负异常,深部海盆区则出现明显的中稀土和重稀土的富集,铕异常变弱,与深部海盆区有基性火山物质的加入的地质事实相吻合.南海表层沉积物稀土元素和微量元素总体上呈现出以陆源沉积为主的特征.其元素平均丰度和各参数值都比较接近陆源河流和中国浅海沉积物,而与深海沉积物和大洋玄武岩差别显著,显示南海沉积物虽然受到火山沉积和生物沉积的混合作用的影响,但其物质源仍然主要来自于周缘大陆.     

东海赤潮高发区沉积物柱状样中正构烷烃和脂肪醇的分布与来源

选取了东海赤潮高发区4个站位的沉积物柱状样,通过测定δ13C_TOC值,利用δ13C的双端元模型计算了沉积物中TOC的海源和陆源贡献率,并分析了正构烷烃和脂肪醇的组成与分布,探讨了其来源。结果表明,东海赤潮高发区沉积物中,正构烷烃以高碳数烷烃为主,有明显的奇碳优势,且呈双峰群分布;各站位总正构烷烃（T-ALK/μg/g）含量随深度有不同的变化;碳数奇偶优势指数（CPI）、陆源海源优势烷烃比（TAR）、平均链长（ACL）等正构烷分子指标,反映出在调查海区陆源正构烷烃的输入占主导,且以草本植物为主。直链烷基醇主要来源于陆地高等植物,4个站位的植醇经历了相似的生物化学过程,说明沉积环境较一致;菜籽甾醇与甲藻甾醇的比值指示了调查海区浮游植物种群的历史变化,由于水体富营养化的日益加重所导致的赤潮由简单的硅藻赤潮向硅藻甲藻混合型赤潮转变。     

白令海陆架区柱样沉积物脂类分子特征及其气候变化响应

为探究全球变暖对于高纬度海洋生态环境的影响,对中国第5次北极科学考察在白令海陆架区采集的BL16柱样沉积物中的脂类进行了研究.沉积物中检测到丰富的饱和烃和脂肪酸等化合物,其组成和分布显示,该沉积柱中有机质为陆源和海源混合输入.其中长链正构烷烃和长链饱和正构脂肪酸主要来源于陆源高等植物,饱和异构和反异构脂肪酸主要来源于海洋自生细菌,短碳链正构烷烃、反异构烷烃和烷基环戊烷烃的浓度相互间有较好的相关性,表明其来源较为一致,主要来源于海洋浮游藻类和细菌.海源短链正构烷烃与陆源长链正构烷烃的比值∑C_15-21/∑C_23-33在0.14~0.90之间,表明该沉积柱中正构烷烃主要以陆源输入为主.沉积柱中短链正构烷烃、反异构烷烃和烷基环戊烷浓度,以及脂肪酸中异构、反异构脂肪酸组分与长链饱和正构脂肪酸组分的相对变化与总有机碳含量（TOC）、总氮含量（TN）变化一致,尤其在20世纪70年代以来明显升高,可能反映了海洋初级生产力持续增加的趋势,并且对全球变暖做出了灵敏的响应.      

Fractionation of carbon isotopes in biosynthesis of fatty acids by a piezophilic bacterium Moritella japonica strain DSK1

We examined stable carbon isotope fractionation in biosynthesis of fatty acids of a piezophilic bacterium Moritella japonica strain DSK1. The bacterium was grown to stationary phase at pressures of 0.1, 10, 20, and 50 MPa in media prepared using sterile-filtered natural seawater supplied with glucose as the sole carbon source. Strain DSK1 synthesized typical bacterial fatty acids (C_14-19 saturated, monounsaturated, and cyclopropane fatty acids) as well as long-chain polyunsaturated fatty acids (PUFA) (20:6ω3). Bacterial cell biomass and individual fatty acids exhibited consistent pressure-dependent carbon isotope fractionations relative to glucose. The observed Δδ_FA-glucose (−1.0‰ to −11.9‰) at 0.1 MPa was comparable to or slightly higher than fractionations reported in surface bacteria. However, bulk biomass and fatty acids became more depleted in ¹³C with pressure. Average carbon isotope fractionation (Δδ_FA-glucose) at high pressures was much higher than that for surface bacteria: −15.7‰, −15.3‰, and −18.3‰ at 10, 20, and 50 MPa, respectively. PUFA were more ¹³C depleted than saturated and monounsaturated fatty acids at all pressures. The observed isotope effects may be ascribed to the kinetics of enzymatic reactions that are affected by hydrostatic pressure and to biosynthetic pathways that are different for short-chain and long-chain fatty acids. A simple quantitative calculation suggests that in situ piezophilic bacterial contribution of polyunsaturated fatty acids to marine sediments is nearly two orders of magnitude higher than that of marine phytoplankton and that the carbon isotope imprint of piezophilic bacteria can override that of surface phytoplankton. Our results have important implications for marine biogeochemistry. Depleted fatty acids reported in marine sediments and the water column may be derived simply from piezophilic bacteria resynthesis of organic matter, not from bacterial utilization of a ¹³C-depleted carbon source (i.e., methane). The interpretation of carbon isotope signatures of marine lipids must be based on principles derived from piezophilic bacteria.     

Prehistoric nutrient inputs and productivity in Narragansett Bay

Calculations by others of the preindustrial deposition of inorganic nitrogen from the atmosphere in the area of Narragansett Bay compared with recent measurements suggest that this flux has increased almost 15 times over natural background. On the basis of modern studies of the export of nitrogen and phosphorus from temperate forests, the prehistoric watershed also probably contributed very little reactive N or P to the bay. New information from undisturbed old-growth forests suggests that most of the N that was exported from the watershed was probably associated with refractory dissolved organic matter and thus contributed little to the fertility of the bay. The largest source of reactive dissolved inorganic nitrogen (DIN) and phosphorus (DIP) for Narragansett Bay under prehistoric conditions was the coastal ocean water entrained in the bay in estuarine circulation. The total input of DIN to this estuary has increased about five-fold and the input of total DIP has approximately doubled as a result of human activities. Recent ecosystem-level experiments using large (13 m³, 5 m deep) mesocosms designed as living models of Narragansett Bay showed that the primary production of phytoplankton in the bay is limited by the supply of DIN and that annual phytoplankton production is strongly correlated with the rate of input of DIN. The relationship between DIN input and annual phytoplankton production in the mesocosms is consistent with observations published by others working in 10 different natural marine systems, and a functional regression of the field and experimental data provides a tool to calculate the rate of prehistoric phytoplankton production that would have been associated with the prehistoric DIN input estimates. The result of this calculation suggests that phytoplankton production in the bay has approximately doubled (from about 130 g C m^?2 yr^?1 to 290 g C m^?2 yr^?1 for a baywide average) since the time of European contact. It also seems likely that seagrasses and macroalgae once made a much larger contribution to total system production than they do today.     

不同类型沉积物中脂肪酸的分布、演化和生烃意义

对近代海洋沉积物、泥炭、福山凹陷第三系泥岩、茂名盆地第三系油页岩和辽河盆地东部凹陷第三系沉积岩剖面等样品中脂肪酸类型和分布特征进行了分析与研究。结果表明以低等浮游动植物为主的沉积中，二元肪酸丰度相对比一元酸占优势。随深程度增加，沥青中脂肪酸高碳数相对减少，低碳数相对增高，偶碳估势逐渐消失。在辽河盆地东部凹陷埋深２２６６ｍ的泥岩中发现脂肪酸仍具有偶碳优势，证明沉积有机质中偶碳脂肪酸优势可以保存到生油高峰前的较高演化阶段，对低熟原油烷烃的生成和具奇碳优势有重要意义。     

Biogeochemical significance of fatty acid distribution in the coastal upwelling ecosystem off Concepción (36°S), Chile

The distribution of fatty acids (FAs) in the water column and surface sediment of the coastal upwelling ecosystem off Concepción (central Chile; almost monthly from February 2007 to November 2008) was analyzed using gas chromatography–mass spectrometry. The concentration of FAs in the water column ranged from 3.4 to 67.7 μg l⁻¹ and showed higher values in surface water than in bottom water, and under upwelling vs. non-upwelling conditions. The content in surface sediment ranged from 21.6 to 328.5 μg g dw⁻¹ and had a higher abundance in February 2007, and January–March and June 2008. In surface water 16:0, 18:0 and 16:1n-7 made up ca. 47% of the FAs during the study period, while in bottom water 16:0, 18:0 and 18:1n-9 accounted for ca. 45%, and in surface sediment ca. 43% was accounted for by 14:0, 16:0, 16:1n-7 and 18:1n-7 FAs. Seasonal variability in the relative abundance of saturated and polyunsaturated FAs (PUFAs) was observed in surface water, while in bottom water and surface sediment no major temporal change in FA composition was observed. A negative exponential relationship between bacterial FAs and PUFAs from surface water and sediment suggests that bacteria may be responsible for ca. 80% of PUFA removal during sinking. We suggest that the FA composition of the surface sediment of the ocean is a consequence of rapid alteration of the FA pool by biological activity in the water column and sediment, driven by the removal of the labile fraction of FAs.     

Climatic and Tidal Forcing of Hydrography and Chlorophyll Concentrations in the Columbia River Estuary

Hydrographic patterns and chlorophyll concentrations in the Columbia River estuary were compared for spring and summer periods during 2004 through 2006. Riverine and oceanic sources of chlorophyll were evaluated at stations along a 27-km along-estuary transect in relation to time series of wind stress, river flow, and tidal stage. Patterns of chlorophyll concentration varied between seasons and years. In spring, the chlorophyll distribution was dominated by high concentrations from freshwater sources. Periods of increased stream flow limited riverine chlorophyll production. In summer, conversely, upwelling winds induced input of high-salinity water from the ocean to the estuary, and this water was often associated with relatively high chlorophyll concentrations. The frequency, duration, and intensity of upwelling events varied both seasonally and interannually, and this variation affected the timing and magnitude of coastally derived material imported to the estuary. The main source of chlorophyll thus varied from riverine in spring to coastal in summer. In both spring and summer seasons and among years, modulation of the spring/neap tidal cycle determined stratification, patterns of mixing, and the fate of (especially freshwater) phytoplankton. Spring tides had higher mixing and neap tides greater stratification, which affected the vertical distribution of chlorophyll. The Columbia River differs from the more tidally dominated coastal estuaries in the Pacific Northwest by its large riverine phytoplankton production and transfer of this biogenic material to the estuary and coastal ocean. However, all Pacific Northwest coastal estuaries investigated to date have exhibited advection of coastally derived chlorophyll during the upwelling season. This constitutes a fundamental difference between Pacific Northwest estuaries and systems not bounded by a coastal upwelling zone.     

海洋浮游生态系统中小型浮游动物的生态功能

小型浮游动物在海洋生态系统中的作用,主要指有多少能量通过小型浮游动物传递到桡足类,从而比较沿"浮游植物→中型浮游动物"和"浮游植物+细菌→小型浮游动物→中型浮游动物"两条食物链到达中型浮游动物的能流大小.为达到这个目的,需要研究各个能流路径的传递效率,即能量在各个营养级(初级生产--小型浮游动物,细菌生产--小型浮游动物,小型浮游动物的生长率,小型浮游动物--中型浮游动物)的传递效率.综述了国内外对上述营养级传递效率的研究现状,以期为我国的同类研究提供参考.浮游植物初级生产力被小型浮游动物摄食的比例平均为每天60%～75%,大大高于桡足类对浮游植物初级生产力的摄食压力每天10%.海洋浮游细茵的二次生产力相当于初级生产力的30%.其中80%～180%被小型浮游动物摄食.小型浮游动物的毛生长率为30%～40%,生产力是初级生产力的21%～34%.在西班牙西北部沿海,桡足类每天摄食2%～51%小型浮游动物生产力.因此,桡足类通过微食物网摄食的能量是初级生产力的0.4%～17%,与桡足类摄食初级生产的10%处于同一量级.不考虑碎屑提供的能流,小型浮游动物对桡足类饵料的贡献为20%以上,甚至可高达50%.     

中国前中生代海相烃源岩发育的构造-沉积条件

中国前中生代主要发育海相沉积,发育多层系、多沉积类型的烃源岩,展示了中国海相层系广阔的油气资源前景。但受构造背景和沉积环境的差异性控制,这些烃源岩的品质和分布规律也存在很大差异。震旦纪—早古生代早期（Z－O2）,中国主要板块处于洋盆扩张、陆块离散的构造—沉积阶段,围绕华北、扬子、塔里木等主要陆块周围,发育被动大陆边缘斜坡相烃源岩,这类烃源岩具有宽带状分布、范围广、品质优、长期继承性发育的特点。早古生代晚期（O3－S）,为洋盆俯冲消减、古中国陆汇聚形成阶段,受板块边缘隆起围限,主要发育台内坳陷烃源岩,这类烃源岩具有面状分布、持续时间较短的特点。晚古生代—中生代早期（D－T）,华北以相对的稳定构造背景为主,主要发育海陆过渡相煤系烃源岩,此类烃源岩具有面状分布、分布面积大、以生气为主的特点;南方以离散构造背景为主,华南台地裂解成“盆包台”格局,在深裂陷内部发育深水盆地相烃源岩,此类烃源岩具有窄带状分布、品质优、分布面积较小的特点。     

Sedimentological characteristics and new detrital zircon SHRIMP U–Pb ages of the Babulu Formation in the Fohorem area,Timor-Leste

Sedimentological characteristics and zircon provenance dating of the Babulu Formation in the Fohorem area, Timor-Leste, provide new insights into depositional process, detailed sedimentary environment and the distribution of source rocks in the provenance. Detrital zircon sensitive high-resolution ion microprobe (SHRIMP) U–Pb ages range from Neoarchean to Triassic, with the main age pulses being Paleozoic to Triassic. In addition, the maximum deposition ages based on the youngest major age peak (ca 256–238 Ma) of zircon grains indicate that the basal sedimentation of the Babulu Formation occurred after the early Upper Triassic. The formation consists predominantly of mudstone with minor sandstone, limestone and conglomerate that were deposited in a deep marine environment. These deposits are composed of six lithofacies that can be grouped into three facies associations (FAs) based on the constituent lithofacies and bedding features: basin plain deposits (FA I), distal fringe lobe deposits (FA II) and medial to distal lobe deposits (FA III). The predominance of mudstone (FA I) together with intervening thin-bedded sandstones (FA II) suggest that the paleodepositional environment was a low energy setting with slightly basin-ward input of the distal part of the depositional lobes. Discrete and abrupt occurrences of thick-bedded sandstone (FA III) within the FA I mudstone suggests that sandstone originated from a collapse of upslope sediments rather than a progressive progradation of deltaic turbidites. This combined petrological and geochronological study demonstrates that the Babulu Formation in the Fohorem area of the Timor-Leste was initiated as a submarine lobe system in a relatively deep marine environment during the Upper Triassic and represents the extension of the Gondwana Sequence at the Australian margin.     

Hypersaline and anoxia in the Devonian Frasnian-Famennian transition :Molecular fossil and mineralogical evidence from Guangxi ,South China

Abundant normal alkanes, isoprenoid hydrocarbons, terpanes and steranes were detected in 23 samples taken from the carbonate platform to basin facies in the Devonian Frasnian-Famennian (F-F) transition of Guangxi, South China. They were mainly derived from the phytoplankton or bacteria and algae. Molecular stratigraphic parameters, abundant micron gypsums and pyrite framboids show that hypersaline and anoxia prevailed in the F-F transition, the highly stressed environments occurred near the F-F boundary. Orbital cyclostratigraphic studies indicate that the hypersaline and anoxia prevailed in the F-F transition spanned an interval at least from the Palmatolepis linguiformis conodont Zone to the Middle Palmatolepis triangularis conodont Zone and lasted about 1.2 Ma. The Devonian marine ecosystem underwent Early Devonian gradual optimization, Middle Devonian to the F-F transitional stepwise deterioration and late Famennian recovery. A positive feedback among higher surface ocean temperatures, hypersaline, water column anoxia, enhanced nutrient regeneration, phytoplankton productivity and eutrophication was probably substantial in the F-F transition in Guangxi, South China, even in other regions of the world, such as Holy Cross Mountains of Poland, Montagne Noire in southern France, Alberta in Canada. The point that should be emphasized is that the decisive and direct causes of the F-F transitional mass extinction would be the stepwise deterioration of the marine ecosystem since the Middle Devonian other than a bolide impact on the earth. The hypersaline and anoxia prevailed in the F-F transition favor the formation and preservation of hydrocarbon source rocks in South China.