全球海平面变化与中国珊瑚礁   总被引：1，自引：0，他引：1       下载免费PDF全文

王国忠 《古地理学报》2005,7(4):483-492

本文以政府间气候变化专业委员会（IPCC）于2001年专门报告中关于21世纪内全球气候变化的温度和海平面变化的预估为前提。简要介绍了中国珊瑚礁的定位、类型和分布,对其进行了成熟度分类,评估了全球海平面变化对中国珊瑚礁的影响。据预测,21世纪我国各海域海平面上升以南海最大,为32 ~ 98cm,其平均上升速率为0.32 ~ 0.98cm/a。从海平面上升速率与珊瑚礁生长速率的理论对比分析,中国珊瑚礁基本上能与前者同步生长,即使海平面以预估高值上升,也不会威胁其生存。从中国珊瑚礁成熟度较高、其生长趋势以侧向生长为主的现实状况出发,未来全球海平面上升能为其创造向上生长的有利条件。从古地理学“将古论今”观点出发,自全新世6000aBP以来曾存在过的高海平面和较高表层海水温度的历史,也可以佐证,21世纪的全球海平面上升不会对中国珊瑚礁的存在和发育造成威胁。现存的珊瑚礁岛应对于全球海平面上升,可以做到“水涨岛高”,它们能够屹立于上升了的未来海平面之上;但对于岛上的人工建筑物则会被浸、被淹,或被淘蚀和破坏,因此必须根据海平面上升的幅度和速率,采取相应的防御措施。  相似文献   

Relationships between porosity,organic matter,and mineral matter in mature organic-rich marine mudstones of the Belle Fourche and Second White Specks formations in Alberta,Canada     

《Marine and Petroleum Geology》2014

This study presents approaches for evaluating hybrid source rock/reservoirs within tight-rock petroleum systems. The emerging hybrid source rock/reservoir shale play in the Upper Cretaceous Second White Specks and Belle Fourche formations in central Alberta, Canada is used as an example to evaluate organic and inorganic compositions and their relationships to pore characteristics. Nineteen samples from a 77.5 m-long core were analyzed using organic petrography, organic geochemistry, several methods of pore characterization, and X-ray powder diffraction (XRD). The lower part of the studied section includes quartz- and clay-rich mudrocks of the Belle Fourche Formation with low carbonate content, whereas the upper portion contains calcareous mudrocks of the Second White Specks Formation. Strata are mineralogically composed of quartz plus albite (18–56 wt. %), carbonates (calcite, dolomite, ankerite; 1–65 wt. %), clays (illite, kaolinite, chlorite; 15–46 wt. %), and pyrite (2–12 wt. %). Petrographic examinations document that organic matter represents marine Type II kerogen partly biodegraded with limited terrestrial input. Vitrinite reflectance R_o (0.74–0.87%), T_max values (438–446 °C) and biomarkers indicate mid-maturity within the oil window. The relatively poor remaining hydrocarbon potential, expressed as an S2 value between 2.1 and 6.5 mg HC/g rock, may result from an estimated 60–83% of the original kerogen having been converted to hydrocarbons, with the bulk having migrated to adjacent sandstone reservoirs. However, the present-day remaining total organic carbon TOC_pd content remains relatively high (1.7–3.6 wt. %), compared with the estimated original TOC_o of 2.4–5.0 wt. %. The calculated transformation ratio of 60–83% suggests that the remaining 17–40 wt. % of kerogen is able to generate more hydrocarbons. The studied section is a tight reservoir with an average Swanson permeability of 3.37·10⁻⁵ mD (measured on two samples) and total porosity between 1.7 and 5.0 vol. % (3 vol. % on average). The upper part of the sandy Belle Fourche Formation, with slightly elevated porosity values (3.5–5 vol. %), likely represents the interval with the best reservoir properties in the studied core interval. Total pore volume ranges between 0.0065 and 0.0200 cm³/g (measured by a combination of helium pycnometry and mercury immersion). Mesopores (2–50 nm ∅) are the most abundant pores and occupy 34–67% of total porosity or a volume of 0.0030–0.0081 cm³/g. In comparison, micropores (<2 nm ∅) cover a wide range from 6 to 60% (volume 0.0007–0.0053 cm³/g), and macropores (>50 nm ∅) reach up to 57% with the exception of some samples failing to indicate the presence of this pore fraction (volume 0.0000–0.0107 cm³/g). Macroporosity is mostly responsible for variations in total porosity, as suggested by macroporosity's strongest correlation with total porosity within the section. The relatively narrow ranges of TOC and minerals contents among measured samples limit our ability to further deconvolute factors that influence changes in total porosity and pore size distribution.  相似文献   

Geochemical characteristics and origin of reservoir bitumens from Well Zhong 1 in the Katake Uplift,Tarim Basin     

Youjun Tang  Ling Zan 《中国地球化学学报》2011,30(3):398-404

The source of marine crude oils from Tarim Basin is still disputed.However,research on the reservoir bitumens may provide a piece of new evidence to elucidate oil source.Geochemical characteristics of reservoir bitumens from different strata from Well Zhong 1 in the Katake Uplift were discussed here in detail.Pr/Ph ratios of reservoir bitumen from Well Zhong 1 range from 1.14 to 1.39,CPI ratios from 1.01 to 1.08,which indicates no odd-even predominance of normal alkanes,with OEP ratios ranging from 0.98 to 1.05.The contents of gammacerane and C28 sterane of reservoir bitumen from Well Zhong 1 are low,while dibenzothiophene series are abundant.Ster-ane isomerization maturity parameter and Ts/(Ts+Tm) ratio indicate that the reservoir bitumen from Well Zhong1 is mature to highly mature.Based on the differences in biomarker distribution,it is concluded that reservoir bitumen from Well Zhong 1,of which molecular parameters are contrary to those in Cambrian oil from Well Tadong 2,origi-nated from the Upper Ordovician source rocks.  相似文献   

西北太平洋柔鱼（Ommastrephes bartramii）繁殖生物学初步研究   总被引：1，自引：0，他引：1       下载免费PDF全文

李思亮  刘必林  陈新军  马金  曹杰  张广文 《海洋与湖沼》2011,42(2):179-185

根据2007年7—10月西北太平洋海域采集的1342尾柔鱼样本,分析其性腺成熟度和性腺成熟度指数等生物学特征,进行繁殖生物学研究。结果表明,总性别比均接近1：1,性成熟个体的雌性比例小于雄性,说明雄性繁殖期较长,性成熟较早。性成熟个体比例的动态变化表明,9月底雌性达到性成熟高峰。8—10月胴长组成出现双峰结构,对应于未...  相似文献   

南海北部陆架区海域深水金线鱼的产卵场     

陈国宝  李永振  陈丕茂 《广东海洋大学学报》2002,22(6):20-25

根据 1997年 12月至 1999年 6月在南海北部陆架区海域进行的底拖网渔业资源调查的资料 ,统计分析了南海北部陆架区海域深水金线鱼性腺成熟期的组成及分布、季节性变化和水深变化规律。结果表明 ,南海北部陆架区海域深水金线鱼的产卵场位于广东沿海水深 6 0～ 15 0m海区 ,尤其是珠江口外海区的群体更为密集 ;该生殖群体的产卵期较长 ,且分布范围大 ,未见有显著性变化。  相似文献   

中国南方海相页岩气选区关键参数探讨   总被引：9，自引：0，他引：9  

郗兆栋  唐书恒  王静  张振  李彦朋  龚明辉  肖何琦 《地质学报》2018,92(6):1313-1323

中国南方海相页岩具有热演化程度高和经历过多期构造运动等特征,基于多个页岩气区块的勘探开发实践,提出了以保存条件为核心、地质评价为重点,兼顾经济评价的页岩气有利区选区思路,筛选出了有机质含量、有机质成熟度和压力系数3项中国南方海相页岩气选区的关键评价指标。有机质含量是页岩气富集成藏的物质基础,在选区时应本着"高中找厚"的原则,即在TOC含量平均较高的页岩层段(系)寻找富有机质页岩连续厚度大的页岩层段;成熟度过高对页岩气的富集成藏有消极的影响,在选区时应本着"高中找低"的原则;压力系数可以直观反映页岩气的保存程度,压力系数越高,表明页岩气的保存程度越好,在选区时应本着"强中找高"的原则,即在强构造的地质背景下寻找压力系数高的区块。以湘西北牛蹄塘组页岩气的实际勘探情况为例,认为湘西北地区牛蹄塘组页岩气具有较好的勘探开发前景,但是成熟度过高和保存条件差(压力系数低)是影响湘西北地区页岩气富集与高产的主要潜在风险。  相似文献   

Diversities in biomarker compositions of Carboniferous–Permian humic coals in the Ordos Basin,China     

Q. Yuan 《Australian Journal of Earth Sciences》2018,65(5):727-738

The molecular composition of Carboniferous–Permian coals in the maturity range from 0.66 to 1.63% vitrinite reflectance has been analysed using organic geochemistry to investigate the factors influencing the biomarker compositions of humic coals. The Carboniferous–Permian coal has a variable organofacies and is mainly humic-prone. There is a significant difference in the distribution of saturated and aromatic hydrocarbons in these coals, which can be divided into three types. The Group A coals have biomarker compositions typical of humic coal, characterised by high Pr/Ph ratios, a lower abundance of tricyclic terpanes with a decreasing distribution from C₁₉ tricyclic terpane to C₂₄ tricyclic terpane and a high number of terrigenous-related biomarkers, such as C₂₄ tetracyclic terpane and C₂₉ steranes. The biomarker composition of Group B coals, which were deposited in a suboxic environment, have a higher abundance of rearranged hopanes than observed in Group A coals. In contrast, in Group C coals, the Pr/Ph ratio is less than 1.0, and the sterane and terpane distributions are very different from those in groups A and B. Group C coals generally have abnormally abundant tricyclic terpanes with a normal distribution maximising at the C₂₃ peak; C₂₇ steranes predominates in the m/z 217 mass fragmentograms. The relationships between biomarker compositions, thermal maturity, Pr/Ph ratios and depositional environments, indicate that the biomarker compositions of Carboniferous–Permian coals in Ordos Basin are mainly related to their depositional environment. This leads to the conclusion that the biomarker compositions of groups A and B coals collected from Shanxi and Taiyuan formations in the northern Ordos Basin are mainly related to their marine–terrigenous transitional environment, whereas the biomarker compositions for the Group C coals from Carboniferous strata and Shanxi Formation in the eastern Ordos Basin are associated with marine incursions.  相似文献   

Identification and geochemical significance of polarized macromolecular compounds in lacustrine and marine oils     

Jingwei Cui  Rukai Zhu  Jian Hu 《中国地球化学学报》2014,33(4):431-438

Polarized macromolecular compounds in typical lacustrine and marine shale oils collected from the Ordos Basin and Tarim Basin of China were analyzed by FT-ICR-MS. Maturity was taken into consideration by diagenesis physical simulation experiments on shale oils, which had been collected at various temperature and pressure stages. The results showed that similar components existed in non-hydrocarbon and asphaltenes and the main peak compound classes of Nl and 02 were potential parameters for identifying typical marine oil and lacustrine oil in China. Nitrogen compounds/（nitrogen compounds and oxygen compounds）, such as Nl/（O2＋Nt）, NL/（Oa＋Nt）, Ni/（NiO1＋N1O2） are the maturity indicators, which are related with C-N and C-O bond energy. Differences in molecular components and weights between marine and lacustrine oils are the effective index to identify source maturity and sedimentary environment.  相似文献   

Natural Gas Types,Distribution Controlling Factors,and Future Exploration in the Western Qaidam Basin   总被引：1，自引：0，他引：1  

GUO Zeqing  SUN Ping  LI Jian  ZHANG Lin  LIU Weihong  TIAN Jixian  ZHANG Shaosheng  ZENG Xu 《《地质学报》英文版》2014,88(4):1214-1226

The Paleogene and Neogene oil and gas in the western Qaidam basin have a regular distribution in three concentric zones from the edge to the center of the basin.Natural gas mainly occurs in the inner zone,and the gas-oil ratio of the northern area of the basin is significantly higher than that of the southern area.Large amounts of carbon isotope data of natural gas,plotted in Xshaped and comprehensive identification diagrams for the southern area and northern area,respectively,were used to identify the types of natural gas.The large-scale distribution of natural gas is highly consistent with the Ro values of major source rocks,but is poorly correlated with the type of organic matter.This indicates that the main controlling factor of natural gas distribution is organic matter maturity,and the kerogen types act as the basis for the formation of different types of natural gas.Paleouplifts and squeezed anticlines near hydrocarbon generation depression centers,which are major natural gas-rich regions,control the migration directions of natural gas,while hydrocarbon migration pathways and fault systems connecting gas sources are the most important factors for natural gas reservoir formation in the inner basin.Therefore,favorable zones for natural gas distribution can be predicted on the basis of the distribution of thermal evolution and the gas generation intensity of major source rocks as well as the structural map.The Shizigou-YoushashanYingdong-Dawusi,Youquanzi –Kaitemilike- Youdunzi,and Xiaoliangshan – Nanyishan- Dafengshan structural belts are favorable zones for natural gas accumulation.This study has important theoretical and practical significance for future natural gas exploration.  相似文献   

鲁乐地区早前寒武纪花岗岩类演化及大陆地壳生长     

李洪奎  耿科  禚传源  梁太涛  陈莉 《山东地质》2012,(4):8-14

通过对太古宙和古元古代花岗岩成分判别分析,提出了鲁东地区早前寒武纪花岗岩类可能分为3期,第一期为中太古代TTG组合,发育不完全;第二期为新太古代T1T2G1组合,具有贫K2O的奥长花岗岩演化趋势;第三期为古元古代早期G2组合,仅具富K2O的钙碱性演化趋势。探讨了不同组合花岗岩的形成环境,新太古代T2T2G1组合为岛弧环境,古元古代早期为大陆碰撞环境;不同的花岗岩类岩石组合分别对应的陆壳成熟度为：T1T2G1组合为新生的初始不成熟陆壳,G2组合则为最终的成熟陆壳。鲁东早前寒武纪花岗岩类随时间从新太古代至古元古代早期的演化,记录了鲁东大陆地壳形成的完整的地质演化过程。  相似文献