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一、对我国石油天然气工业发展历史、现状、前景的评估 1、世界天然气工业,从50年代以来迅速发展。1950年世界剩余探明储量为8.5万亿m~3,1988年初已达111.9万亿m~3。其探明储量大约每十年翻一番。据十二届世界石油大会(1987年,美国休斯敦)资料介绍,尚可寻找的储量为119万亿m~3。以目前年产约1.5～1.8万亿m~3(有人预测2020年年产可达2.0万亿m~3)计算,世界天然气储量可维持开采100年以上。从全球来看,在可望的未来,天然气仍是不可替代的重要能源和化工原料。天然气工业仍处于蓬勃发展的趋势。 相似文献
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A large scale model test of a 1 × 2 pile group was conducted in silts to investigate its behavior under eccentric lateral loading. The model pile group consisted of two well instrumented steel piles and was installed in a large soil tank with a close spacing of three-pile diameters on centers. The test results revealed that the eccentricity of lateral loads had limited effect on the overall performances of the 1 × 2 pile group, but significantly contributed to the unevenness of internal forces of the individual piles. The coupling effect between the lateral deflection and torque gave rise to the substantial increase in the torsional resistance of individual piles within the group, comparing to that of a torsionally loaded single pile. The contribution provided by the torsional resistances of individual piles in resisting the external torque continually decreased when the applied lateral load increased. In addition, a three-dimensional finite-element analysis for the pile group was performed and the simulated response was found to be in good agreement with the measured test results. Based on the same model, more cases with different loading conditions were further analyzed. It could be concluded from the analyses that the layout of individual piles within the group obviously affected the behavior of the 1 × 2 pile group under eccentric lateral loads. 相似文献
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The Mount Woods Domain in the Gawler Craton, South Australia records a complex tectonic evolution spanning the Palaeoproterozoic and Mesoproterozoic. The regional structural architecture is interpreted to represent a partially preserved metamorphic core complex that developed during the ~1600–1580 Ma Hiltaba Event, making this one of the oldest known core complexes on Earth. The lower plate is preserved in the central Mount Woods Domain, which comprises the Mount Woods Metamorphics. These rocks yield a detrital zircon maximum depositional age of ~1860 Ma and were polydeformed and metamorphosed to upper amphibolite to granulite facies during the ~1740–1690 Ma Kimban Orogeny. The upper plate comprises a younger succession (the Skylark Metasediments) deposited at ~1750 Ma. Within the upper plate, sedimentary and volcanic successions of the Gawler Range Volcanics were deposited into half graben that evolved during brittle normal faulting. The Skylark Shear Zone represents the basal detachment fault separating the upper and lower plate of the core complex. The geometry of normal faults in the upper plate is consistent with NE-SW extension.Both the upper and lower plates are intruded by ~1795–1575 Ma Hiltaba Suite granitic and mafic plutons. The core complex was extensively modified during the ~1570–1540 Ma Kararan Orogeny. Exhumation of the western and eastern Mount Woods Domain is indicated by new 40Ar/39Ar biotite cooling ages that show that rock packages in the central Mount Woods Domain cooled past ~300 °C ± 50 °C at ~1560 Ma, which was ~20 million years before equivalent cooling in the western and eastern Mount Woods Domain. Exhumation was associated with activity along major syn-Kararan Orogeny faults. 相似文献
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This paper reports in situ observations on barite (0 0 1) surface dissolution behavior in 0.1–0.001 M NaCl solutions at 30 °C using atomic force microscopy (AFM). The step retreating on barite (0 0 1) surfaces changed with increasing NaCl solution concentrations. In solutions with a higher NaCl concentration (⩾0.01 M), many steps showed curved or irregular fronts during the later experimental stage, while almost all steps in solutions with a lower NaCl concentration exhibited straight or angular fronts, even during the late stage. The splitting phenomenon of the initial 〈h k 0〉 one-layer steps (7.2 Å) into two half-layer steps (3.6 Å) occurred in all NaCl solutions, while that of the initial [0 1 0] one-layer steps observed only in the 0.1 M NaCl solution. The step retreat rates increased with an increasing NaCl solution concentration. We observed triangular etch pit and deep etch pit formation in all NaCl solutions, which tended to form late in solutions with lower NaCl concentrations. The deep etch pit morphology changed with increasing NaCl solution concentrations. A hexagonal form elongated in the [0 1 0] direction was bounded by the {1 0 0}, {3 1 0}, and (0 0 1) faces in a 0.001 M NaCl solution, and a rhombic form was bounded by the {5 1 0} and (0 0 1) faces in 0.01 M and 0.1 M NaCl solutions. An intermediate form was observed in a 0.005 M NaCl solution, which was defined by {1 0 0}, a curved face tangent to the [0 1 0] direction, {3 1 0}, and (0 0 1) faces: the intermediate form appeared between the hexagonal and rhombic forms in solutions with lower and higher NaCl concentrations, respectively. The triangular etch pit and deep etch pit growth rates also increased with the NaCl solution concentration. Combining the step and face retreat rates in NaCl solutions estimated in this AFM study as well as the data on the effect of water temperature on the retreat rates reported in our earlier study, we produced two new findings. One finding is that the retreat rates increase by approximately two-fold when the NaCl solution concentration increases by one order of magnitude, and the other finding is that the retreat rate increase due to a one order of magnitude increase in the NaCl concentration corresponds to an increase of approximately 8 °C in water temperature. This correlation may help to understand and evaluate increasing dissolution kinetics induced by the different mechanisms where barite dissolution is promoted by the catalytic effect of Na+ and Cl− ions (through an increase in the NaCl solution concentration) or by an increase in the hydration of Ba2+ and SO42− (through an increase in water temperature). 相似文献
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《地学前缘(英文版)》2022,13(6):101431
Melt inclusions in kimberlitic minerals and diamonds indicate that chlorides are important constituents of mantle carbonatite melts. Besides, alkaline chlorides are important constituents of saline high-density fluids (HDFs) found in diamonds from kimberlites and placers around the world. Continuous compositional variations suggest that saline and carbonatitic HDFs could be genetically linked. However, the essence of this link remains unclear owing to the lack of data on phase relations in the chloride-carbonate systems under pressure. Here we studied subsolidus and melting phase relations in the system NaCl–CaCO3–MgCO3 at 6 GPa and 1000–1600 °C using a Kawai-type multianvil press. We found that at 1000 °C, subsolidus assemblage consists of halite, magnesite, and aragonite. At higher temperatures, the stabilization of dolomite splits the subsolidus area into two partial ternary fields: halite + magnesite + dolomite and halite + dolomite + aragonite. The minimum on the liquidus surface corresponds to the halite-dolomite-aragonite ternary eutectic, situated at 1100 °C. The eutectic melt has Ca# 89 and contains 30 wt.% NaCl (26 mol% 2NaCl). The system has two ternary peritectics: halite + dolomite = magnesite + liquid located near the ternary eutectic and magnesite + dolomite = Mg-dolomite + liquid situated between 1300 and 1400 °C. Although under dry conditions incipient melting yields carbonate-dominated melt, the addition of water facilitates the fusion of NaCl and expands the liquid field to NaCl-rich compositions with up to 70 wt.% NaCl. The obtained results favor the idea that hydrous saline melts/fluids (brines) found as inclusions in diamonds could be a lower temperature derivative of mantle carbonatite melts and disagree with the hypothesis on chloride melt generation owing to the chloride-carbonate liquid immiscibility since no such immiscibility was established. We also studied the interaction of the NaCl–CaCO3–MgCO3 system with iron metal and found that carbonate reduction produces C-bearing species (Fe0, Fe-C melt, Fe3C, Fe7C3, C0) and wüstite containing Na2O, CaO, and MgO. Besides, a carbonate chloride compound, Ca2Cl2CO3, was established among the reaction products. The interaction between NaCl-bearing carbonate melt shifts its composition toward Mg-poor and NaCl-rich. Given the above, an alternative hypothesis can be proposed, according to which the interaction of alkaline chloride-bearing carbonate melts formed in the subduction zones with the reduced mantle should be accompanied by diamond crystallization and shift the composition of the melt from carbonatitic to alkali-rich saline. 相似文献
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《Gondwana Research》2014,25(1):30-47
The ca. 2.45–2.0 Ga supracratonic record of six cratonic terranes (Superior Province, Hearne Domain, Fennoscandian crustal segment, and São Francisco, Pilbara and Kaapvaal cratons) is investigated. A <~2415–2420 basal unconformity appears pervasive, floored by basement lithologies for the three “Kenorland-related” terranes (Superior, Hearne and Fennoscandian) and by passive margin chemical sedimentary platform deposits for the apparently “non-amalgamated” cratons. Palaeosols are locally associated with this unconformity, and glacigenic lithologies, for all of the “non-amalgamated” cratons as well as for Superior. A relatively complete sedimentary record is recorded for the three Kenorland supercontinent terranes, including at least two glacial events, whereas hiatuses characterise the Pilbara and São Francisco cratons, with an incomplete record for Kaapvaal. Evidence for geodynamic reactivation at ca. 2.2 Ga includes widespread mafic dykes and volcanics, orogenies in Pilbara and São Francisco, glaciation in Kaapvaal and Pilbara, and significant transgressions thereafter on many of the cratonic terranes. While the overall ca. 2.45–2.2 Ga records studied here are at least compatible with the postulated global magmatic slowdown of Condie et al. (2009), distinct differences between the records associated with “Kenorland-related” and “non-amalgamated” cratons might reflect thermal subsidence and associated sedimentation accompanying the slowdown for the former group (where thermal blanketing likely played a role), while elevated freeboard and concomitant erosive regimes accompanied the inferred slowdown for the latter group. 相似文献
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Qi Fu Peng Lu Hiromi Konishi Robert Dilmore Huifang Xu W.E. Seyfried Chen Zhu 《Chemical Geology》2009,258(3-4):125-135
Batch reactor experiments were conducted to assess perthitic alkali-feldspar dissolution and secondary mineral formation in an initially acidic fluid (pH = 3.1) at 200 °C and 300 bars. Temporal evolution of fluid chemistry was monitored by major element analysis of in situ fluid samples. Solid reaction products were retrieved from two identical experiments terminated after 5 and 78 days. Scanning electron microscopy revealed dissolution features and significant secondary mineral coverage on feldspar surfaces. Boehmite and kaolinite were identified as secondary minerals by X-ray diffraction and transmission electron microscopy. X-ray photoelectron spectroscopy analysis of alkali-feldspar surfaces before and after reaction showed a trend of increasing Al/Si ratios and decreasing K/Al ratios with reaction progress, consistent with the formation of boehmite and kaolinite.Saturation indices of feldspars and secondary minerals suggest that albite dissolution occurred throughout the experiments, while K-feldspar exceeded saturation after 216 h of reaction. Reactions proceeded slowly and full equilibrium was not achieved, the relatively high temperature of the experiments notwithstanding. Thus, time series observations indicate continuous supersaturation with respect to boehmite and kaolinite, although the extent of this decreased with reaction progress as the driving force for albite dissolution decreased. The first experimental evidence of metastable co-existence of boehmite, kaolinite and alkali feldspar in the feldspar hydrolysis system is consistent with theoretical models of mineral dissolution/precipitation kinetics where the ratio of the secondary mineral precipitation rate constant to the rate constant of feldspar dissolution is well below unity. This has important implications for modeling the time-dependent evolution of feldspar dissolution and secondary mineral formation in natural systems. 相似文献
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Kent C.Condie 《地学前缘(英文版)》2018,9(1):51-60
Many geological and geochemical changes are recorded on Earth between 3 and 2 Ga.Among the more important of these are the following:(1)increasing proportion of basalts with"arc-like"mantle sources;(2)an increasing abundance of basalts derived from enriched(EM)and depleted(DM)mantle sources;(3)onset of a Great Thermal Divergence in the mantle;(4)a decrease in degree of melting of the mantle;(5)beginning of large lateral plate motions;(6)appearance of eclogite inclusions in diamonds;(7)appearance and rapid increase in frequency of collisional orogens;(8)rapid increase in the production rate of continental crust as recorded by zircon age peaks;(9)appearance of ophiolites in the geologic record,and(10)appearance of global LIP(large igneous province)events some of which correlate with global zircon age peaks.All of these changes may be tied directly or indirectly to cooling of Earth's mantle and corresponding changes in convective style and the strength of the lithosphere,and they may record the gradual onset and propagation of plate tectonics around the planet.To further understand the changes that occurred between 3 and 2 Ga,it is necessary to compare rocks,rock associations,tectonics and geochemistry during and between zircon age peaks.Geochemistry of peak and inter-peak basalts and TTGs needs to be evaluated in terms of geodynamic models that predict the existence of an episodic thermal regime between stagnant-lid and plate tectonic regimes in early planetary evolution. 相似文献
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《International Journal of Earth Sciences》1913,4(1):60-62
International Journal of Earth Sciences - 相似文献
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The most widely accepted origin of n-alkan-2-ones in peats is the microbial oxidation of the related n-alkanes and/or oxidative decarboxylation of fatty acids derived from plant input. The distributions of n-alkanes and n-alkan-2-ones in 48 samples from the Roñanzas 6000 cal. yr BP peat bog profile (N Spain) do not justify a single source. The n-alkan-2-ones typically dominate the n-alkanes, maximizing at C19 or C25/C27, whereas the n-alkanes maximized either at C23 or at C31/C33. The averaged δ13C values of the n-alkanes ranged from −32.3‰ to −33.1‰, but those of the n-alkan-2-ones were consistently higher (−29.2‰ to −29.9‰), suggesting a different, probably bacterial, source for the ketones. 相似文献
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Denis Thiéblemont Christine Flehoc Michel Ebang-Obiang Christophe Rigollet Jean-Pierre Prian François Prognon 《Comptes Rendus Geoscience》2013,345(7-8):272-283
We present new 14C data on charcoal fragments recovered from the lower (coarse-grained Stone Line) and upper (fine-grained Cover Horizon) portions of surficial formation profiles in Gabon. These data and others compiled from the literature enable a reconstruction of the Upper Holocene geological regional history of Gabon. The connection between the geological events recorded in the surficial formations and the Upper Holocene environmental crisis is discussed and a scenario connecting geological events with climatic and environmental changes is proposed. Such a scenario suggests that following the climatic crisis, the reconstitution of soils by aeolian sedimentation could have been an important factor of Bantu expansion. 相似文献
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由国家科学基金委地球科学部主办的“秦岭造山带学术讨论会”于1989年11月在西安召开。其目的在于交流秦岭造山带地质研究的最新成果和新观点、新认识、新方法;并根据当前学科发展和国民经济建设的需要,围绕秦岭造山带岩石圈的组成、结构及其演化的中心议题,集中讨论需进一步深入研究的关键科学问题,研究内容和主攻方向,为国家自然科学基金重大项目的设立提供科学依据。 会议得到国内地学界广泛响应和热情支持,来自教学、科研和生产部门的论文摘要达298篇(选编成册268篇)。经学术讨论会的学术委员会评审,确定会议代表85人,宣讲论文52篇、展示论文33篇;而实际到会代表达121名,来自全国的68个单位,且绝大部分是多年 相似文献
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M.I. Epov V.L. Mironov P.P. Bobrov I.V. Savin A.V. Repin 《Russian Geology and Geophysics》2009,50(5):470-474
We have measured the dielectric spectra of sand and bentonite mixtures with oil and saline water (NaCl solution) in the frequency range from 50 MHz to 16 GHz at 22 °C. The measured spectra were compared with predictions in terms of the generalized refractive mixing dielectric model (GRMDM), and the respective error was estimated as a check of the model applicability to describe oil-bearing formations. The results may be useful in developing new methods of electromagnetic logging. 相似文献