山东重大基础地质问题研究进展

在1∶50万山东省大地构造相图编制和大地构造相综合研究的基础上,作者对山东重大基础地质问题提出了新的划分方案.山东地块是经多期增生和碰撞、镶嵌、叠覆而成的,其漫长的地质构造演化具明显的阶段性,可分为前南华纪、南华纪-中三叠世和晚三叠世-第四纪三大构造演化阶段.大地构造分区分为陆块区、造山系和叠加造山-裂谷系,划分出3个Ⅰ级构造单元、5个Ⅱ级构造单元、18个Ⅲ级构造单元和55个Ⅳ级构造单元.基于鲁东和鲁西地区在地层建造、岩浆活动、构造格局和成矿作用等存在的重大差异性,新厘定的渤海陆块作为华北陆块区之下的Ⅱ级构造单元.厘定大别-苏鲁造山带的北部边界、鲁西陆块与渤海陆块的边界.对古元古代荆山群、粉子山群形成的构造环境进行了深入探讨,认为是弧后盆地靠近大陆边缘一侧的构造背景,在古元古代晚期的造山过程中,粉子山群和荆山群等均卷入了造山过程,其中荆山群发生了深俯冲及高压麻粒岩相变质作用.胶东地区构造-岩浆事件和金矿成矿作用受控于特提斯、古亚洲洋和太平洋三大构造域,金矿形成于中生代构造体制转折和岩石圈减薄的动力学背景,与华北板块和扬子板块碰撞及太平洋板块的俯冲机制存在密切成因关系.     

Rosetta-Alice observations of exospheric hydrogen and oxygen on Mars

The European Space Agency’s Rosetta spacecraft, en route to a 2014 encounter with comet 67P/Churyumov-Gerasimenko, made a gravity assist swing-by of Mars on 25 February 2007, closest approach being at 01:54 UT. The Alice instrument on board Rosetta, a lightweight far-ultraviolet imaging spectrograph optimized for in situ cometary spectroscopy in the 750-2000 Å spectral band, was used to study the daytime Mars upper atmosphere including emissions from exospheric hydrogen and oxygen. Offset pointing, obtained five hours before closest approach, enabled us to detect and map the H i Lyman-α and Lyman-β emissions from exospheric hydrogen out beyond 30,000 km from the planet’s center. These data are fit with a Chamberlain exospheric model from which we derive the hydrogen density at the 200 km exobase and the H escape flux. The results are comparable to those found from the Ultraviolet Spectrometer experiment on the Mariner 6 and 7 fly-bys of Mars in 1969. Atomic oxygen emission at 1304 Å is detected at altitudes of 400-1000 km above the limb during limb scans shortly after closest approach. However, the derived oxygen scale height is not consistent with recent models of oxygen escape based on the production of suprathermal oxygen atoms by the dissociative recombination of .     

东日本大地震地震序列的震源机制解特征及其动力学意义

日本本州及其邻近区域的应力状态以及弧后盆地的演化机制一直是人们所关注的问题.本文对2011年3月11日东日本大地震地震序列(2011年3月11日至2012年3月15日)的哈佛双力偶解进行了聚类分析,得到五种类型的震源机制解:与主震类型一致的低倾角逆断层型地震;主张应力方向垂直于日本海沟走向的正断层型地震;主张应力方向平行于日本海沟走向的正断层型地震;主压应力方向平行于日本海沟走向的逆断层型地震;包括走滑型地震在内的其他类型地震.东日本大地震地震序列中发生在弧前增生楔地震的震源机制解与大地震发生之前地震的震源机制解特征有显著区别,反映出该地区的应力状态与震前相比有较大改变.东日本大地震及其前震释放了附近区域的累积弹性应力,主震破裂区附近太平洋板块和其上覆板块接近完全解耦,降低了日本海盆地、中国东北地区的近东西向挤压应力水平.不过,整个本州岛东部区域太平洋板块和其上覆板块并没有完全解耦,但应力水平并不高.我们认为,日本海及中国东北应力水平的降低会使该区域的近东西向挤压型地震的危险性降低,而使NNE-SSW走向的走滑型地震活动性增强.同时,火山活动性也会增强.尤其是本州岛地区,存在近期火山爆发的可能性.东日本大地震地震序列的震源机制解特征还提示我们,日本海的应力状态及日本海的演化可能在一定程度上取决于太平洋板块和上覆板块的耦合状态.持续的弱耦合将不仅使得弧后大范围的地区保持岩浆上涌所必须的拉伸应力环境,而且还会因弧前隆起区发育大量正断层型地震而向深部提供促使岩浆生成所必须的水,因而造成日本海的再次扩张.     

Adaptive geo-information processing service evolution: Reuse and local modification method

Geo-information (GI) service automated composition according to user demands is a crucial task in spatial data infrastructures. State-of-the-art GI service composition approaches face serious limitations in terms of effectiveness and stability as the general GI processing service chain (GIPSC) must be generated from individual user specifications from scratch. This paper presents a novel approach called an adaptive geo-information service evolution (AgiSE) method which overcomes these limitations by adaptively reusing and modifying previously generated GIPSC. In this method, an influence domain minimisation (IDM) criterion is employed to modify the existing GIPSC to fit the new (changed) user demands through minimum revisions. The correction of local modification is ensured by process and integrity constraints. An innovative algorithm called influence domain pursuit is developed to find the optimised solution through a heuristic backward search based on the defined IDM. Experimental analysis shows the significant improvements of using AgiSE in GI services compared with existing traditional methods. The benefits of AgiSE are the improved efficiency of GI service composition and the improved executing stability of GIPSC which were achieved by reducing the service provider load. The AgiSE presented in this paper is crucial in reusing a general unified framework for GI service composition.     

On the evolution and stability of interfacial ripples on and off the critical frequency

Abstract

Under consideration are interfaces between two media of different densities and which arise from the interaction between the Mth and Nth harmonics of the motion where 1 ≤ N < M. By means of the method of multiple scales in both space and time a pair of nonlinear coupled partial differential equations is derived which model the progression of the interface. The equations contain a detuning parameter [sgrave] which allow imperfections in the resonance to be taken into account. Stokes-type sinusoidal solutions to the equations were sought. It was found that solutions exist for all values of the interaction ratio M/N. In some situations interfaces exist at both exact and near resonance; while in others they are destroyed by amplifications in the detuning. In yet others, a quantity of detuning is actually necessary for the profiles to exist. In all cases, even when the parameters are fixed, a very large class of interface profiles is possible. Finally, the stability of the profiles is studied. It is found that some are quite stable, even to perturbations with wavenumbers close to the main flow.     

Divergent evolution of Earth and Venus: Influence of degassing,tectonics, and magnetic fields

Knowledge of the earliest evolution of Earth and Venus is extremely limited, but it is obvious from their dramatic contrasts today that at some point in their evolution conditions on the two planets diverged. In this paper we develop a geophysical systems box model that simulates the flux of carbon through the mantle, atmosphere, ocean, and seafloor, and the degassing of water from the mantle. Volatile fluxes, including loss to space, are functions of local volatile concentration, degassing efficiency, tectonic plate speed, and magnetic field intensity. Numerical results are presented that demonstrate the equilibration to a steady state carbon cycle, where carbon and water are distributed among mantle, atmosphere, ocean, and crustal reservoirs, similar to present-day Earth. These stable models reach steady state after several hundred million years by maintaining a negative feedback between atmospheric temperature, carbon dioxide weathering, and surface tectonics. At the orbit of Venus, an otherwise similar model evolves to a runaway greenhouse with all volatiles in the atmosphere. The influence of magnetic field intensity on atmospheric escape is demonstrated in Venus models where either a strong magnetic field helps the atmosphere to retain about 60 bars of water vapor after 4.5 Gyr, or the lack of a magnetic field allows for the loss of all atmospheric water to space in about 1 Gyr. The relative influences of plate speed and degassing rate on the weathering rate and greenhouse stability are demonstrated, and a stable to runaway regime diagram is presented. In conclusion, we propose that a stable climate-tectonic-carbon cycle is part of a larger coupled geophysical system where a moderate surface climate provides a stabilizing feedback for maintaining surface tectonics, the thermal cooling of the deep interior, magnetic field generation, and the shielding of the atmosphere over billion year time scales.     

中国气候变迁及其对地理环境的影响

总结了五千年中国历史上的气候变化的特征，论述了气候的冷暖周期性变迁对中国历史地理环境的影响。     

关于盆地分析思想的发展

中国海陆地区内,沉积岩的分布面积达550万平方公里.这些沉积岩所存在的盆地保留着各种地质作用的记录,赋存着石油天然气和煤炭等矿产资源,是探索地质历史的窗口,也是国民经济建设的重要能源基地.因此,盆地的分析研究显得格外重要,其分析理论思想经历了直观阶段、发展阶段和深化阶段.目前比较完善的是运用综合地球物理方法研究盆地的一套系统工程理论,并将刘光鼎教授提出的综合地球物理解释方法学进一步深化.本文还讨论了盆地分析的有关理论基础.     

我国历史时期的湖泊围垦与湖泊退缩

根据历史资料记载,我国历史时期的湖泊围垦可分为三个时期,即魏晋——南北朝、南宋和明末清初。近乎90％的古湖泊消失于这些时期。大多数学者认为,人口增长导致湖泊围垦、退缩。本文进一步的研究表明,湖泊田垦时期与气候干旱期、黄河和长江的低水位期相吻合:与此同时,湖泊也处于低水位期。