The paper deals with the Lower Kungurian (Philippovian Horizon; Lower Permian) biota of the Middle Cis-Urals, Russia. The biota is characterized on the basis of four representative localities (Philippovskoe Bus-stop, Philippovskian Quarry, Kamai and Kiselevo-Suksun Highway), which are situated in the stratotype area of the Kungurian stage. All the localities can be regarded as Lagerstätten, but of authentically low biodiversity, since they represent oligotrophic lagoons of abnormal fluctuating salinity. General reconstruction of the Philippovian near-shore shallow-water ecosystem is given. Two new species of algae Algites philippoviensis sp. nov., A. shurtanensis sp. nov., and a new species of the limulids Paleolimulus kunguricus sp. nov. are described for the first time.
In recent years, many fossil vertebrates, including feathered dinosaurs, have been discovered at Nanshimenzi village, Gangou Town, Qinglong County, Hebei Province, China. A geological section including the fossil-bearing strata was measured at Nanshimenzi, to determine the exact geological age and sedimentary characteristics of the section, and a new lithostratigraphic unit was named as the Nanshimenzi Bed. The Nanshimenzi Bed is about 56.6 m in thickness, mainly consisting of gray sandstones and siltstones and containing fossil vertebrates and several coal streaks. On the basis of survey and comparison, the Nanshimenzi Bed should be assigned to Tiaojishan Formation and probably to the upper part of the formation.
The authors presented geochronology and geochemical data of diorites from Nancha gold deposit in Tonghua region, with the aim to constraining its formation age, magma source and tectonic setting. LA-ICP-MS U-Pb dating results of zircons from the diorites indicate that the rocks were formed in the Middle Jurassic (171±2 Ma, MSWD=1.19). Geochemically, these rocks have SiO2 concentrations of 52.52%-54.90%, K2O of 2.14%-3.84%, Na2O of 3.17%-3.35%, MgO of 7.43%-9.34% and high Mg# of 68.57-72.57. These rocks are characterized by enrichment in large ion lithophile elements(LILE, such as K, Ba, Rb and Sr)and light rare earth elements (LREE), relatively depletion in high field strength elements (HFSE, such as Ta, Nb, Ti and Zr), and heavy rare earth elements (HREE). These characteristics suggest that primary magma of the rocks were derived from the partial melting of mantle with miner crustal contamination, which may related to partial melting of mantle wedge by addition of sediment melt from subducting oceanic crust. Based on former and present studies, the authors consider that the Nancha ore deposit high-Mg diorites were formed in compressional structural setting which is similar to volcanic arc. It could be related to the subduction of the Paleo-Paci-fic plate beneath the Eurasian continent.
Zircon LA-ICP-MS U-Pb age and whole-rock geochemistry data are presented for the Hutouya granodiorite porphyries in Mengyin, western Shandong, to restrict its petrogenesis. The analyzed zircons exhibit oscillatory growth zoning and core-rim textures in the cathodoluminescence images and have high Th/U ratios (0.04-1.66), indicating its magmatic origin. The youngest group of magmatic zircon yields weighted mean 206Pb/238U age of 132±2 Ma, which represents the forming age of the granodiorite porphyries, i.e., the Early Cretaceous. The oldest group of magmatic zircon 207Pb/206Pb ages ranges from 2 398 Ma to 2 370 Ma, yielding a weighted mean age of 2 389±23 Ma, suggesting that the basement of the North China Craton should exist in the research area. Geochemically, the samples are characterized by high SiO2 (70.38% and 64.87%), low MgO (0.60% and 1.53%) and Mg# values (42.92 and 50.42). Moreover, they show enrichment of light rare earth elements and large ion lithophile elements (e.g. Rb, Ba and K), depletion of heavy rare earth elements and high field strength elements (e.g. Nb and Ta), positive anomaly of Pb, and negative anomaly of Ti. These results, together with previously published data, indicate that the Hutouya granodiorite porphyries were derived from partial melting of a delaminated lower continental crust and subsequent interaction with the mantle peridotites. They are consistent with the period of lithospheric thinning beneath the eastern North China Craton and may be formed in an extensional tectonic environment.
Spectral conjugate gradient method is an algorithm obtained by combination of spectral gradient me-thod and conjugate gradient method, which is characterized with global convergence and simplicity of spectral gradient method, and small storage of conjugate gradient method. Besides, the spectral conjugate gradient method was proved that the search direction at each iteration is a descent direction of objective function even without relying on any line search method. Spectral conjugate gradient method is applied to full waveform inversion for numerical tests on Marmousi model. The authors give a comparison on numerical results obtained by steepest descent method, conjugate gradient method and spectral conjugate gradient method, which shows that the spectral conjugate gradient method is superior to the other two methods.
Along with the economic development, large tunnels need to be constructed in many high mountains or complex structure regions, and the design and construction of detailed tunnel exploration become particularly important. Transient electromagnetic method (TEM) uses a non-grounded loop or an electrode to send a primary electromagnetic pulse into the ground, and observes spatial and temporal distribution of secondary electromagnetic field, which is widely applied in mineral resource exploration, engineering geology, etc. The application of TEM in the tunnel construction of Kaiyuan Temple is researched in this study. The smoke loop inversion is adopted for inverting the transient electromagnetic data. The drilling data and high density resistivity method data are combined for comparison. The obtained inversion result greatly coincides with the actual conditions. Therefore, the geophysical prospecting basis can be provided for the division of stratum, delineation of geologi-cal structure, and design and construction of tunnel pavement. By virtue of TEM, drilling data and high density resistivity method, the tunnel construction of Kaiyuan Temple has obtained satisfactory results.
There is usually source effect in the field work of controlled-source audio-frequency magnetotelluric method. Source effect is a thorny problem during field working, data processing and interpretation. Therefore, it is very important for the results of field prospecting to model source effect and summarize its influence rules. Based on the previous research, the authors use 3D finite difference method to simulate the electromagnetic field and set different anomaly situation to study the source effect in near-field measurement, then conclude the in-fluence rules of source effect. Simulations provide the reference for the actual field work and data processing to correct the influence of source effect, so the information of the underground will be more approaching to the real.
Based on surfaced-related multiple elimination (SRME), this research has derived the methods on multiples elimination in the inverse data space. Inverse data processing means moving seismic data from forward data space (FDS) to inverse data space (IDS). The surface-related multiples and primaries can then be separated in the IDS, since surface-related multiples will form a focus region in the IDS. Muting the multiples energy can achieve the purpose of multiples elimination and avoid the damage to primaries energy during the process of adaptive subtraction. Randomized singular value decomposition (RSVD) is used to enhance calculation speed and improve the accuracy in the conversion of FDS to IDS. The synthetic shot record of the salt dome model shows that the relationship between primaries and multiples is simple and clear, and RSVD can easily eliminate multiples and save primaries energy. Compared with conventional multiples elimination methods and ordinary methods of multiples elimination in the inverse data space, this technique has an advantage of high calculation speed and reliable outcomes.
In order to make more available methods for natural jadeite quality evaluation, this study applied rigorous coupled wave theory to calculate and simulate the reflection characteristics of various natural jadeites, and establish evaluation standard based on the relationship between refractive index and reflectivity and responses of reflection efficiency to refractive index, grating thickness and incident angles, etc. The results suggest that reflection efficiency varies significantly as a function of the natural jadeite quality, which can provide a new method to evaluate natural jadeite.