南极半岛北部陆架的演化及其油气潜能

在１９８７年美国南极研究计划Ｐｏｌａｒ Ｄｕｋｅ航次在南极半岛北部陆架采集了３２００ｋｍ地震反射剖面，结核陆地研究及ＤＳＤＰ３５４航次成果，我们地该区域的构造、气体演化史及可能的油气前景进行了分析评价。     

Marine debris collects within the North Pacific Subtropical Convergence Zone

Floating marine debris, particularly derelict fishing gear, is a hazard to fish, marine mammals, turtles, sea birds, coral reefs, and even human activities. To ameliorate the economic and environmental impact of marine debris, we need to efficiently locate and retrieve dangerous debris at sea. Guided by satellite-derived information, we made four flights north of Hawaii in March and April 2005. During these aerial surveys, we observed over 1800 individual pieces of debris, including 122 derelict fishing nets. The largest debris concentrations were found just north of the North Pacific Transition Zone Chlorophyll Front (TZCF) within the North Pacific Subtropical Convergence Zone (STCZ). Debris densities were significantly correlated with sea-surface temperature (SST), chlorophyll-a concentration (Chla), and the gradient of Chla. A Debris Estimated Likelihood Index (DELI) was developed to predict where high concentrations of debris would be most likely in the North Pacific during spring and early summer.     

布格重力异常建模反演在二连盆地油气勘探中的应用

二连盆地由众多小凹陷组成,伊和凹陷是其中之一.重力资料在盆地"探边摸底"、"定凹选带"等方面发挥着重要作用.本文基于布格重力异常资料,利用2.5D建模反演技术对其中横跨主洼槽的两条测线进行可视化建模及正演拟合.其中,初始模型的几何参数取自二维地震解释结果;物性参数中的纵向密度取自测井声波波速与密度的相关公式.正演拟合为建模反演技术的关键环节,密度横向变化,是在拟合过程中通过人机交互试错调整实现.通过正演拟合,揭示了主洼槽沉积层横向和纵向均存在较大的密度不均匀性,主洼槽有利于油气生成.与地震解释结果对比,二者在赛汉组-第四纪、腾格尔组深度相差不大,但凹陷底部拟合结果与地震解释结果有明显差异.通过钻井结果验证,正演拟合各沉积层深度与钻井揭示的各层深度结果一致,二维地震解释结果偏浅,其可能原因是时深转换选取的速度值偏小造成.     

Orogenesis and Basin Development: U-Pb Detrital Zircon Age Constraints on Evolution of the Late Paleozoic St. Marys Basin, Central Mainland Nova Scotia

The St. Marys Basin, along the southern flank of the composite Late Paleozoic Magdalen Basin in the Canadian Appalachians and along the Avalon-Meguma terrane boundary, contains Late Devonian-Early Carboniferous continental clastic rocks of the Horton Group that were deposited in fluvial and lacustrine environments after the peak of the Acadian orogeny. SHRIMP II (Geological Survey of Canada) data on approximately 100 detrital zircons from three samples of Horton Group rocks from the St. Marys Basin show that most of the zircons have been involved in a multistage history, recycled from clastic rocks in the adjacent Meguma and Avalonian terranes. Although there is a minor contribution from Early Silurian (411 Ma) and Late Devonian suites (ca. 380-370 Ma), Neoproterozoic (ca. 700-550 Ma) and Paleoproterozoic (ca. 2.0-2.2 Ga) zircon populations predominate, with a minor contribution from ca. 1.0-, 1.2-, and 1.8-Ga zircons. Published U-Pb single-zircon analyses on clastic sedimentary rocks indicate that the Meguma and Avalon terranes have different populations of detrital zircons, sourced from discrete portions (Amazonian and West African cratons) of the ancient Gondwanan margin. Both terranes contain Neoproterozoic and Late Archean populations. The SHRIMP data, in conjunction with published sedimentological and geochemical data, indicate that the Horton Group basin-fill sediments are largely the result of rapid uplift and erosion of Meguma terrane metasedimentary and granitoid rocks immediately to the south of the St. Marys Basin during the waning stages of the Acadian orogeny. Regional syntheses indicate that this uplift occurred before and during deposition and was a consequence of dextral ramping of the Meguma terrane over the Avalon terrane along the southern flank of the Magdalen Basin.     

The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458

Three new silicon-bearing radicals of astrophysical interest, SiCCH and the two nearly isoenergetic isomers SiCN and SiNC, were detected in a laboratory discharge in their X2Pi ground states by Fourier transform microwave and millimeter-wave absorption spectroscopy. Hyperfine structure was observed in the low rotational transitions of the (2)Pi(1/2) ladder, and well-resolved Lambda-doubling was observed in both fine-structure ladders. With the spectroscopic constants derived from the laboratory measurements, the spectra of all three can be calculated to an uncertainty of less than 0.1 km s(-1) in equivalent radial velocity over the entire range of interest to radio astronomers. SiCN, with a dipole moment of 2.9 D, is probably the most promising of the three for astronomical discovery.     

Measurement of Charge Exchange and X-Ray Emission Cross Sections for Solar Wind-Comet Interactions

X-ray emission from a comet was observed for the first time in 1996. One of the mechanisms believed to be contributing to this surprisingly strong emission is the interaction of highly charged solar wind ions with cometary gases. Reported herein are total absolute charge-exchange and normalized line-emission (X-ray) cross sections for collisions of high-charge state (+3 to +10) C, N, O, and Ne ions with the cometary species H2O and CO2. It is found that in several cases the double charge-exchange cross sections can be large, and in the case of C3+ they are equal to those for single charge exchange. Present results are compared to cross section values used in recent comet models. The importance of applying accurate cross sections, including double charge exchange, to obtain absolute line-emission intensities is emphasized.     

地球扁率在地质历史上的变化下限

为研究地球形状的长期变化,将地球假设为弹性椭球体,根据弹性动力学理论导出地球的扁率下限公式,扁率与地球的平均密度ρ、引力加速度g、自转角速度ω、平均半径R、弹性模量E、泊松比v相关.将新星云假说下地质历史时期半径、质量和角速度变化值代入公式计算出各地质历史时期地球扁率值,作为地球扁率变化值的下限值.地球的扁率自地球形成以来总体变化趋势是在减小.