Eigensensitivity analysis of moisture-related buckling of marine composite panels

In this paper, an approximate closed-form solution is presented to compute the moisture-related buckling of symmetric angle-ply laminates. The environment corresponds to a steady state condition, which provides a uniform moisture distribution for the laminate. The laminate consists of four layers [θ/−θ]_s constructed of low, moderate and high stiffness ratio materials. Comparative results using the Rayleigh–Ritz method provides a means of assessing the accuracy of the expression. For certain laminate architectures, several modes must be computed to ascertain the lowest buckling mode, and once identified, provides an excellent approximation for the mode computed using the Rayleigh–Ritz method.     

Inversion of multiple thermal indicators: Quantitative methods of determining paleoheat flux and geological parameters. III. Stratigraphic age determination from inversion of vitrinite reflectance data and sterane isomerization data

Thermal indicator data are used in an inverse mode to determine ages of stratigraphic horizons simultaneously with paleoheat flux. Results from blind tests on wells with horizon ages ranging from Ordovician through Carboniferous and Jurassic to Miocene indicate that thermal indicator inversions are capable of resolving such ages to within about 10% uncertainty. Results using the inversion procedure with one thermal indicator (vitrinite reflectance) were comparable to the results using another independent thermal indicator (sterane isomerization) in the same well. The activation energy for sterane isomerization was determined to be 30±15 kJ mol^–1. In addition: (a) the age of a stratigraphic horizon, the thickness of eroded sediments at an unconformity, and the variation of paleoheat flux with time were determined simultaneously by thermal indicator inversion in a single well; (b) two neighboring wells, less than 10 km apart, provided essentially identical ages for the same formation when tested using the inversion procedure. The ability to determine stratigraphic horizon ages from inversion of thermal indicator data implies that sedimentation rates can be determined; thus, basinal evolution can be inferred to a degree of resolution not previously obtainable from assumed interpolation methods applied to determine the age of horizons between a limited set of stratigraphic horizons of known ages.     

北京十三陵中元古界长城系沉积相标志及沉积环境演化模式

北京十三陵地区中元古界长城系包括5个组：常州沟组、串岭沟组、团山子组、大红峪组、高于庄组，前2个组主要由碎屑岩组成，后3个组主要由碳酸盐岩组成。众多的沉积相标志从不同侧面说明：常州沟组沉积属于滨浅海碎屑岩沉积环境；从串岭沟组开始，其沉积环境向碳酸盐岩沉积环境过渡；后3个组沉积时的环境为典型的陆表海碳酸盐岩沉积环境。在综合研究的基础上给出了沉积环境演化模式。另外，长城系还有许多特殊的沉积现象值得进一步研究和讨论：世界上最古老的宇宙球粒；高于庄组白云岩层面上双脊波痕的内碎屑颗粒成因和硅化白云岩内青鱼骨状层理及硅质团粒的成因；特别是在大红峪组首次发现太阳星云物质－碳质球粒陨石。     

Interrelations between coeval mafic and A-type silicic magmas from composite dykes in a bimodal suite of southern Israel, northernmost Arabian–Nubian Shield: Geochemical and isotope constraints

Late Neoproterozoic bimodal dyke suites are abundant in the Arabian–Nubian Shield. In southern Israel this suite includes dominant alkaline quartz porphyry dykes, rare mafic dykes, and numerous composite dykes with felsic interiors and mafic margins. The quartz porphyry chemically corresponds to A-type granite. Composite dykes with either abrupt or gradational contacts between the felsic and mafic rocks bear field, petrographic and chemical evidence for coexistence and mixing of basaltic and rhyolitic magmas. Mixing and formation of hybrid intermediate magmas commenced at depth and continued during emplacement of the dykes. Oxygen isotope ratios of alkali feldspar in quartz porphyry (13 to 15‰) and of plagioclase in trachydolerite (10–11‰) are much higher than their initial magmatic ratios predicted by equilibrium with unaltered quartz (8 to 9‰) and clinopyroxene (5.8‰). The elevation of δ¹⁸O in alkali feldspar and plagioclase, and extensive turbidization and sericitization call for post-magmatic low-temperature (≤ 100 °C) water–rock interaction. Hydrous alteration of alkali feldspar, the major carrier of Rb and Sr in the quartz–porphyry, also accounts for the highly variable and unusually high I(Sr) of 0.71253 to 0.73648.

The initial ¹⁴³Nd/¹⁴⁴Nd ratios, expressed by ε_Nd(T) values, are probably unaltered and show small variation in mafic and felsic rocks within a narrow range from + 1.4 to + 3.3. The Nd isotope signature suggests either a common mantle source for the mafic and silicic magmas or a juvenile crustal source for the felsic rocks (metamorphic rocks from the Elat area). However, oxygen isotope ratios of zircon in quartz porphyry [δ¹⁸O(Zrn) = 6.5 to 7.2‰] reveal significant crustal contribution to the rhyolite magma, suggesting that mafic and A-type silicic magmas are not co-genetic, although coeval. Comparison of ¹⁸O/¹⁶O ratios in zircon allows to distinguish two groups of A-type granites in the region: those with mantle-derived source, δ¹⁸O(Zrn) ranging from 5.5 to 5.8‰ (Timna and Katharina granitoids) and those with major contribution of the modified juvenile crustal component, δ¹⁸O(Zrn) varying from 6.5 to 7.2‰ (Elat quartz porphyry dykes and the Yehoshafat alkaline granite). This suggests that A-type silicic magmas in the northern ANS originated by alternative processes almost coevally.