Variations of under-ice currents in Southern Baikal by data of 2012–2016

New data on under-ice currents in Lake Baikal have been obtained with the use of high-accuracy instruments. The obtained data were used to analyze the time and space variations of under-ice currents, to calculate the coefficients of horizontal turbulent exchange and turbulent energy dissipation rates, and to derive spectral estimates of the obtained results. The estimated structures of the under-ice boundary layer near the Angara opening and far from it (up to 5 km) were compared.     

Cristobalite in the 2011–2012 Cordón Caulle eruption (Chile)

Cristobalite is a low-pressure high-temperature polymorph of SiO₂ found in many volcanic rocks. Its volcanogenic formation has received attention because (1) pure particulate cristobalite can be toxic when inhaled, and its dispersal in volcanic ash is therefore a potential hazard; and (2) its nominal stability field is at temperatures higher than those of magmatic systems, making it an interesting example of metastable crystallization. We present analyses (by XRD, SEM, EPMA, Laser Raman, and synchrotron μ-cT) of representative rhyolitic pyroclasts and of samples from different facies of the compound lava flow from the 2011–2012 eruption of Cordón Caulle (Chile). Cristobalite was not detected in pyroclasts, negating any concern for respiratory hazards, but it makes up 0–23 wt% of lava samples, occurring as prismatic vapour-deposited crystals in vesicles and/or as a groundmass phase in microcrystalline samples. Textures of lava collected near the vent, which best represent those generated in the conduit, indicate that pore isolation promotes vapour deposition of cristobalite. Mass balance shows that the SiO₂ deposited in isolated pore space can have originated from corrosion of the adjacent groundmass. Textures of lava collected down-flow were modified during transport in the insulated interior of the flow, where protracted cooling, additional vesiculation events, and shearing overprint original textures. In the most slowly cooled and intensely sheared samples from the core of the flow, nearly all original pore space is lost, and vapour-deposited cristobalite crystals are crushed and incorporated into the groundmass as the vesicles in which they formed collapse by strain and compaction of the surrounding matrix. Holocrystalline lava from the core of the flow achieves high mass concentrations of cristobalite as slow cooling allows extensive microlite crystallization and devitrification to form groundmass cristobalite. Vapour deposition and devitrification act concurrently but semi-independently. Both are promoted by slow cooling, and it is ultimately devitrification that most strongly contributes to total cristobalite content in a given flow facies. Our findings provide a new field context in which to address questions that have arisen from the study of cristobalite in dome eruptions, with insight afforded by the fundamentally different emplacement geometries of flows and domes.     

Solar control of the ionosphere at heights between 100 and 200 km—A comparison of theory and experimental data

Theoretical results on the vertical distribution of ionospheric plasma in the E and F1 layers are reviewed, and compared with experimental data. Treated generally are ion production and recombination, particularly the role of vibrationally excited nitric oxide ions. Emphasis is placed on the conditions responsible for the valley between the E and F1 regions.Finally, certain invariants, that is functional relationships between particular parameters of the distribution of ionospheric plasma, are created and their uses evaluated.     

On the material invariant of 110°-conjugate angle of shear bands——Reply to Gomez-Rivas and Griera(2015)

After their experimental data were re-explained in terms of the maximum-effective-moment(MEM) criterion, Gomez-Rivas and Griera(2015) challenge the validity of the MEM-Criterion in terms of shear fractures, which have mixed up with shear fractures and shear bands. The two features are similar in appearance but different in deformation mechanism(s). The MEM-criterion proves that ?55? to ?1 are the maximum effective moment directions and the shear bands that formed by material-line(beddings or fabrics) rotation mechanism have a constant conjugate angle of 110?. Theoretically, the 55? or 110? is a material-invariant, and practically, a statistic-invariant or preferred direction with average deviation of ~10?. By this angle, shear bands can be easily recognized from shear fractures with conjugate angle never over 90?. The High-strain deformation in the lozenges usually predates the surrounding shear bands. Two stress states can not coexisted simultaneously in the same place and the resolving ?1′ normal to the related shear zone represents 0–100% deformation partitioning, depending on the original kinematic vorticity of the shear zones.     

From solar terms to medical terms(Part Ⅰ): A first step with big data

The story of the Twenty-four Solar Terms(24-ST_s) is one of the most popular elements in Chinese culture, which has a profound influence on agriculture production, health care, and even daily life in both ancient and modern China. This traditional calendric system was invented by the Chinese ancestors through combining fundamental astronomical knowledge with climatic and phenological conditions in the Yellow River Basin some 2000 years ago. Although the basic philosophy of the 24-ST_s remains valid for the country as a whole to date, their regional robustness has been increasingly challenged by accumulating observational data in terms of temporal shift and spatial inhomogeneity. To tackle these issues, we propose to recalibrate the medically related critical timings of Great Heat and Great Cold in the classic ST system by using big meteorological data, and adjust them by introducing geographically correlated analytical models. As a result, a novel calendric system, called the Twenty-four Medical Terms(24-MT_s), has been developed as an upgraded version of the traditional 24-ST_s. The proposed 24-MT_s are characterized by two striking features with respect to the 24-ST_s: A varying duration of each MT instead of a fixed one for the ST, and a geographically dependent timing for each MT instead of a unified one for the entire nation. As such, the updated 24-MT_s are expected to provide a more realistic estimate of these critical timings around the year, and hence, a more precise guidance to agronomic planning and health care activity in China.     

Wavelet analysis of paleomagnetic data: 4. Characteristic short times (0.4–4.5 ky) of variations in the elements of the geomagnetic field during the early Jaramillo reversal and in the stationary field during the Matuyama and Jaramillo chrons (Western Turkmenia)

The geomagnetic variations with characteristic times ranging from 0.4 to 15 ka are shown to be largely stochastic. Variations with different characteristic times appear during different time intervals and reflect accelerating and decelerating processes. The variations do not exhibit any predominant times. At the same time, almost periodic variations in the lithological characteristics are clearly seen in the wavelet diagrams of the parameters that reflect the changes in the composition (quantitative and qualitative) of ferrimagnetic material; i.e., the changes in the conditions of sedimentation related to climate variations. The variations with periods of 5, 8.5, and 13 ka are concurrent with the similar variations in the paleomagnetic data, while the variations with a period of 3.5 ka are only observed in the magnetic parameters. We suggest that the first mentioned oscillations reflect the changes of the external (relative to the Earth) origin, whereas the changes with a period of 3.5 ka are caused by some terrestrial factors.     

Comparisons, processing and interpretation of the surveyed data by GMS-06 and other magnetotelluric sounding systems

In recent years, the data collecting and processing of magnetotelluric sounding （MT） have progressed greatly. How to improve the quality of field surveyed data and obtain the high quality parameters such as apparent resistivity and phase is the most important link during the overall flow. It is closely related to the signal-to-noise ratio of magnetic sensors, the resolution of data collecting units and relevant processing methods as well. Produced by Germany Metronix Measurement Instruments and Electronics Ltd., the new type multi-channel geophysical measurement system GMS-06 was already adopted and used by domeslic units such as Institute of Geology and Geophysics of Chinese Academy of Sciences and Tongji University. Based on the brief introduction of GMS-06, this paper will give the comparisons and analyses of the synchronous surveyed MT data by GMS-06, MMS-03 MT system which was also produced by Metronix and V5-2000 MT system produced by Canada Phoenix Geophysics Ltd.. Then the preliminary processing and interpretation results of the long period MT data observed by GMS-06 in the area of Shanghai and Zhejiang are also discussed in the paper.     

ANDRA underground research laboratory: interpretation of the mineralogical and geochemical data acquired in the Callovian–Oxfordian formation by investigative drilling

Under the ANDRA Meuse/Haute Marne underground research laboratory scientific programme, two boreholes (EST204 and EST205) were drilled to a depth of 510 m for the purposes of scientific characterisation. Twenty-nine core samples were taken in borehole EST205 every 3 m between 422 and 504 m depth. Physical property measurements (water content, porosity, density, specific surface), geochemical analyses (major and trace elements, cation exchange capacity [CEC] and surface cation occupancy, leaching anions, redox state, organic matter concentration), and a semi-quantitative mineralogical study were conducted on the samples.As the rocks are in a reduced state, the core samples were stored under nitrogen immediately after drilling. All the steps of the sampling and of the characterisation are done with a research of limitation of the oxidation to obtain representative samples of the in situ conditions.The top of the formation is more carbonate-rich, with interbedded clayey layers and carbonate rock. The formation is more homogeneous in its central section with a clay mineral concentration of 45–50%, which corresponds to a maximum of flooding within the area. In the upper part of this section, micas and mixed-layer illite/smectite R0 dominate, whereas in the lower part of the section we find an abrupt transition to mixed-layer illite/smectite R1 associated with kaolinite.A statistical analysis, including the data of major and trace elements with the semi-quantitative mineralogy, enabled the identification of some mineralogical traps for trace elements. The values of cation occupancy at the surface of the clay minerals provided a good image of the pore water chemistry; pore water is in equilibrium with the clay surfaces. Leaching experiments revealed the pore water salinity and provided profiles of Cl and Br concentrations. Cl/Br values in the centre of the formation are close to the present-day seawater ratio, which could indicate a seawater origin of the pore water. Some measurements of total reduced capacity, provide quantified results of the reduced state of the rock.Processing the data on water content, helium and petroleum pycnometry enabled calculation of total rock porosity and gave an uncertainty range for this value. Finally, the high BET(N₂) specific surfaces are consistent with the clayey nature of the rock.     

Quantitative data about active tectonics and possible locations of strong earthquakes in the future in the northwestern Beijing

Introduction Northwestern Beijing covers the mountainous area from 114~116.5E and 39~41N, which is located at the joint place of the basically E-W trending Yanshan, the NE to NNE-trending Shanxi and the NW-trending ZhangjiakouPenglai active tectonic belts (regions). The long history of development and evolution in tectonics have formed the features of basin-range tectonics and multi-sets of fault systems with different ranges. Generally, they can be divided as NNE-NE, NNW-NW and appr…     

The 3D profile inversion of the MTS–MVS data by the example of the Shiveluch volcanic zone in the Kamchatka Peninsula

The joint use of the magnetovariational (MV) and magnetotelluric (MT) data and the a priori information about the areal distribution of the deep electrical conductivity within the studied area and the integral conductance of the sedimentary cover enabled us to conduct a three-dimensional (3D) inversion of these data and construct the 3D model of the northeastern part of Kamchatka. The results show that within the Shiveluch volcano, north and south of it, there are northwesterly striking conductive faults penetrating up to the mantle which ascends from a depth of 41 to 35 km. The electrical conductivity of these crustal structures which accommodate high seismic and volcanic activity is probably accounted for by fluid saturation.     

Variations in solar radiation in the solar activity cycle: Response of Earth’s atmospheric parameters (numerical modeling and analysis of observational data)

The results of a three-dimensional numerical simulation of changes in the temperature and wind within a height range of up to 100 km caused by changes in fluxes in the solar ultraviolet (UV) radiation in the 23rd solar activity cycle (which was characterized by unusually low values of UV-radiation fluxes) and also of global changes in the ozone content are presented. The simulation results showed that the response of the temperature to variations in the UV radiation are substantially of a nonzonal character, which is caused by the presence in the model of sources of quasi-stationary waves corresponding to the observational data.     

Comprehensive Information Interpretation in Oil and Gas Exploration—An Example of Buried-Hill Oil and Gas Field in the Jizhong area

The petroleum geophysical and geological comprehensive interpretation with whole-information of gravitational, magnetic, electrical and seismic methods has played an important role in the exploration and development of the buried-hill oil and gas pools in the Jizhong area, including the oil pools in the weathering surface of the buried-hill with “oil generated in the Cenozoic and accumulated in thePaleozoic”, and the gas pools in the buried-hill with “oil generated in both the Cenozoic and the Paleozoic, accumulated in the Paleozoic and sealed by the Mesozoic”. In recent years,high-precision gravitational and magnetic surveying and continuous electromagnetic profile (CEMP) prospecting were carried out on the Yangcun Slope that had been preliminarily recognized as a monocline in the Paleozoic structural-stratigraphy. After the geophysical and geological comprehensive interpretation with whole-information of gravitational,magnetic, electric and seismic data, the gas-bearing buriedhill zone of Matou-Huanghuadian was discovered.     

Magneto- and biostratigraphy of the Jurassic/Cretaceous boundary in the Lókút section (transdanubian range,Hungary)

Jurassic-Cretaceous sediments of Transdanubian Range in Northern Hungary mostly retain their primary magnetizations and are suitable for detailed bio- and magnetostratigraphic studies. The Lókút section, 13 m in thickness, is localized in the central part of the Transdanubian Range. It contains the Jurassic/Cretaceous boundary in pelagic carbonate facies. Although the colour of the rocks changes from reddish-pinkish in the bottom to almost white at the top of the section, magnetite was identified as a magnetic carrier without evidence of hematite. Integrated bio- and magnetostratigraphical investigations resulted in construction of chronostratigraphical scheme. The section, embraces magnetozones from M21r to M18r, of upper Lower Tithonian (Parastomiosphaera malmica Zone) to Lower Berriasian age (Calpionella alpina Subzone). Sedimentation rate of pelagic limestones increased from 1–3 m/My during Tithonian to 5–7 m/My during Berriasian. The sedimentation rate and its changes up the section are comparable to those from the Jurassic/Cretaceous boundary sections of Trento plateau (Southern Alps, Italy) — sedimentary environments of Trento plateau and central Transdanubian Range in that time might be similar. Sedimentation rate within Umbrian Apennine basins and Križna unit in the Western Tatra Mts. seems significantly higher. Analysis of rock magnetic parameters reveals that detrital input was much lower into the Lókút section than into Križna basin in the Tatra Mts. (Zliechov trough). Increase of sedimentation rate occurs in both sections in the Upper Tithonian — Lower Berriasian. It coincides with the onset of calpionellid limestone facies and is related to increased productivity of calcareous micro- and nannoplankton. Detailed correlation of both sections basing on rock magnetic parameters and susceptibility changes is, however, not possible. They are dependent mostly on the local sedimentary conditions (Bakony Mts. — deep water plateau; Križna unit — deep water trough) and correlation with any “global” paleoenvironmental (climatic, eustatic) trends is not straightforward.     

Contemporary (1960–2012) Evolution of the Climate and Surface Mass Balance of the Greenland Ice Sheet

We assess the contemporary (1960–2012) surface mass balance (SMB) of the Greenland ice sheet (GrIS), its individual components and trends. We use output of the high-resolution (11 km) regional atmospheric climate model (RACMO2), evaluated with automatic weather stations and GRACE data. A persistent negative North Atlantic oscillation index over the last 6 years resulted in the summertime advection of relatively warm continental air toward the GrIS. Added to the enhanced radiative forcing by increased CO₂ levels, this has resulted in an increase in near-surface temperature of more than 2 K during 2007–2012 compared to 1960–1990. The associated decrease in albedo led to an extra absorption of shortwave radiation of ～6 Wm^?2 (11 %) in the summer months, which is the main driver of enhanced surface melting and runoff in recent years. From 1990 onward, we see a steady increase in meltwater runoff and an associated decrease in the SMB, accelerating after 2005, with the record low SMB year in 2010. Despite the fact that the GrIS was subject to the highest surface melt rates in 2012, relatively high accumulation rates prevented 2012 to set a record low SMB. In 2012, melt occurred relatively high on the ice sheet where melt water refreezes in the porous firn layer. Up to 2005, increased runoff was partly offset by increased accumulation rates. Since then, accumulation rates have decreased, resulting in low SMB values. Other causes of decreased SMB are the loss of firn pore space and decreasing refreezing rates in the higher ablation area. The GrIS has lost in total 1,800 ± 300 Gt of mass from surface processes alone since 1990 and about half of that in the last 6 years.     

Spheroidal oscillations of the Earth stimulated by the Sumatra-Andaman earthquake with CDSN data

The 0S2~0S54 spheroidal modes of Earth’s free oscillations, triggered by the great Sumatra-Andaman earthquake of 26 December 2004 are retrieved from VHZ data recorded by seven upgraded stations of China Digital Seismograph Network (CDSN). We compare these spheroidal modes with theoretical free oscillation spectra calculated from the Preliminary Reference Earth Model (PREM) and find a coincidence between their periods. Spectral splitting phenomenon is observed obviously in 0S2, 0S3, 0S4, 2S1 and 1S2 free oscillation modes. What is most noticeable is that the oscillation mode 2S1 is reported for the second time (the first time by Rosat et al) without any data stacking. We simulated the split singlet of 0S2 mode on seven CDSN stations based on general focal mechanism and seismic moment of the earthquake. The result shows that seismic moment of the earthquake can reach 1023 N.m. We also find that the recording of Earth’s free oscillations carries abundant information of source mechanism and earthquake location, which is applicable to the detailed study of source rupture parameters.     

Determination of the direction and magnitude of recent tectonic stress in the Xianshuihe fault zone using fault slip data

ＤｅｔｅｒｍｉｎａｔｉｏｎｏｆｔｈｅｄｉｒｅｃｔｉｏｎａｎｄｍａｇｎｉｔｕｄｅｏｆｒｅｃｅｎｔｔｅｃｔｏｎｉｃｓｔｒｅｓｓｉｎｔｈｅＸｉａｎｓｈｕｉｈｅｆａｕｌｔｚｏｎｅｕｓｉｎｇｆａｕｌｔｓｌｉｐｄａｔａ谢富仁，李宏Ｆｕ－ＲｅｎＸＩＥａｎｄＨｏｎｇ...     

Study on noise in simultaneous geomagnetic difference data caused by the effect of Sq local-time varlauon

A new concept is suggested on tectonomagnetic research about the noise in simultaneous geomagnetic difference data caused by the effect of S _q local-time variation, together with the method of theoretical calculation. The level of the noise and its contribution to the total noises of the differences data are analyzed. The result indicates that the noise increases linearly with the increase of the distance between the two stations in the range of 40° longitude-difference, and its increasing rate is about 0.4 nT/(°) at latitude 40°N. The example calculated at a pair of sites with longitude-difference 0.357°, shows that the noise is about one fifth of the total noises of the difference data on geomagnetic quiet-day. Contribution No. 06FE3008, Institute of Geophysics, China Earthquake Administration.     

Study on noise in simultaneous geomagnetic difference data caused by the effect of S_q local-time variation

Introduction It is well known that the local geomagnetic field would change during the pregnancy of an earthquake, which may be associated with the change of the electromagnetic impedances of the crust medium. This phenomenon has been paid attention for a long time and up to now a lot of work both in observation and theory of tectonomagnetism has been carried out and much progress has been achieved (Stacey, 1964; Johnston, 1978; QI, 1977; Rikitake et al, 1980; Shapiro and Ab-dullabekov, 1982…     

Mineral chemistry, geochemistry and U-Pb SHRIMP zircon data of the Yangxin monzonitic intrusive in the foreland of the Dabie orogen

The lower Yangtze River area, situated at the fore-land of the Qinling-Dabie orogen, is an important re-gion for high-grade mineral deposits in Cen-tral-Eastern China. Nearly 300 different types of Cu and Au polymetal, Fe, and S mineral deposits have been found and mined in this zone[1,2]. The overall distribution of these deposits follows the trend of the Mesozoic igneous rocks, suggesting their fundamental controls on the formation of these deposits. Geo-physical and geologic observatio…     

Predicting the distribution of reservoirs by applying the method of seismic data structure characteristics： Example from the eighth zone in Tahe Oilfield

Seismic data structure characteristics means the waveform character arranged in the time sequence at discrete data points in each 2-D or 3-D seismic trace. Hydrocarbon prediction using seismic data structure characteristics is a new reservoir prediction technique. When the main pay interval is in carbonate fracture and fissure-cavern type reservoirs with very strong inhomogeneity, there are some difficulties with hydrocarbon prediction. Because of the special geological conditions of the eighth zone in the Tahe oil field, we apply seismic data structure characteristics to hydrocarbon prediction for the Ordovician reservoir in this zone. We divide the area oil zone into favorable and unfavorable blocks. Eighteen well locations were proposed in the favorable oil block, drilled, and recovered higher output of oil and gas.