山东东营凹陷新生代天文地层表简介

综合山东东营凹陷郝科1等6口井的天文地层研究结果提出"东营凹陷新生代天文地层表",表中列出的是"国际地层表(2004)"、"中国区域年代地层表(2000)"和0—65Ma期间天文偏心率405ka周期编号以及东营凹陷孔店组(顶部)至平原组各组的年龄以及东营凹陷新生代51Ma以来3个大的地层不整合:1)沙河街组二段下部,大约33.8—33.4Ma期间405ka周期振幅不明显、100ka周期较强,与南大西洋33.4—33.7Ma和热带太平洋33.6—33.7Ma期间沉积物中显著转折等特征可作对比;2)东营组-馆陶组界线上下,东营组三角洲顶面最后萎缩时间约为24.467Ma,推测由此至渐新世末(23.03Ma),大约近1.5Myr期间本区没有大的湖泊,而是冲积—河流相沉积,中新世初(23.03Ma)快速隆起,直到约18—16Ma开始馆下段的上部沉积,这一区域性角度不整合面形成大约持续5—7Myr;3)上新统-更新统界线上下,根据本区东辛2-4井古地磁和天文地层研究,测出布容、松山、高斯和吉尔伯特等4个极性时,求出2.546Ma—1.806Ma期间[明上(上)亚段顶]可能沉积并剥蚀过的地层厚度为129m;1.806—0.908Ma期间,因构造活动本区上升成为高山,第四系平一段底部形成了大的不整合面。     

山东济阳坳陷始新统-渐新统天文地层界线年龄分析

山东济阳坳陷沙河街组上部天文地层研究是以牛38井沙三段中亚段顶界年龄34.892Ma作为标定,分析和计算出沙二段下亚段底年龄为33.799Ma、沙段二段上亚段底为33.338Ma、沙一段底为32.940Ma和东营组底为31.829Ma。从天文地层界线年龄分析,沙三段-沙二段界线的年龄大致可对比为"国际地层表(2004)"始新统-渐新统界线年龄33.90Ma,而沙二段下亚段-上亚段界线年龄比国际始新统-渐新统界线的滞后大约600ka。在"中国区域地层表"始新统-渐新统界线年龄(32Ma)和"国际地层表"的始新统-渐新统界线年龄(33.9Ma)之差的1.9Myr,大致相当于本区计算的沙一、二段的持续时间。SP数据的小波分析表明,在沙二段-沙三上亚段界线附近,即约33.8Ma之后,约405ka周期开始变得不明显、不规则,幅度亦下降,剧烈突变发生时间在33.4Ma左右。上述界线对应偏心率周期的理论值突变的时间。因此推论始新世-渐新世转折期是偏心率多个理论周期重迭而导致的一个特殊的时期,也是本区沙二段下亚段这段地层形成不整合面的时间,大约在33.8—33.4Ma期间。     

2022年《中国学术期刊影响因子年报》发布——《地球学报》复合影响因子2.578

<正>由《中国学术期刊(光盘版)》电子杂志社有限公司、中国科学文献计量评价研究中心和清华大学图书馆出版的《中国学术期刊影响因子年报(自然科学与工程技术)(2022年版)》(简称《年报》)已发布。根据《年报》的统计结果,在105种地质类期刊中,《地球学报》2022年影响力指数为377.707,排名第21,复合影响因子是2.578,分区为Q1(表1)。《年报》采用的统计分析方法体现了如下8个特点:     

首届人类世科学大会在西安成功举办

2023年6月17—18日,首届“人类世科学大会”在古都西安成功举办,本次会议由中国地质学会主办,中国地质学会人类世研究分会、中国科学院地球环境研究所、黄土科学全国重点实验室（筹）、陕西省基础学科（地球系统科学）研究中心共同承办。     

Turning points in black holes astrophysics

Black hole astrophysics is expected to have a major breakthrough any day. Theoretical understanding is well advanced, so the breakthrough has to come from observers. Conclusive and direct evidence of event horizons, signatures of tidal deformation of gas clouds (and eventual disappearance of matter behind horizons) could be obtained in matter of months. At this juncture, we wish to summarize how the subject came to this stage and what is the state-of-the-art flow solution around a black hole. We touch upon the most crucial issue of (un)predictability of this subject. We believe that if viscosity is roughly what MRI simulations are pointing to us, we still require very detailed knowledge of properties of the companion, especially time dependent mass transfer from the companion to the black hole.     

Optical observations of the broad-lined type Ic supernova SN 2012ap

The optical observations of the type Ic supernova(SN Ic) SN 2012 ap in NGC 1729 are presented. A comparison with other SNe Ic indicates that SN 2012 ap is highly reddened(with E(B- V)host～0.8 mag) and may represent one of the most luminous SNe Ic ever observed, with an absolute V-band peak magnitude of ～-19.3±0.5 mag after extinction correction. The near-maximum-light spectrum shows wide spectral features that are typical of broad-lined SNe Ic. One interesting feature in the spectrum is the appearance of some narrow absorption features that can be attributed to the diffuse interstellar bands, consistent with the large reddening inferred from the photometric method. Based on the light curves and the spectral data, we estimate that SN 2012 ap produced a56 Ni mass of ～ 0.3 ± 0.1M in the explosion, with an ejecta mass of 2.4+0.7-0.7M and a kinetic energy of E5K= 1.1+0.4-0.4× 102 erg. The properties of its progenitor are also briefly discussed.     

Contrasting Aerodynamic Morphology and Geochemistry of Impact Spherules from Lonar Crater,India: Some Insights into Their Cooling History

The ~50 or 570 ka old Lonar crater, India, was excavated in the Deccan Trap flood basalt of Cretaceous age by the impact of a chondritic asteroid. The impact-spherules known from within the ejecta around this crater are of three types namely aerodynamically shaped sub-mm and mm size spherules, and a sub-mm sized variety of spherule, described as mantled lapilli, having a core consisting of ash-sized grains, shocked basalt and solidified melts surrounded by a rim of ash-sized materials. Although, information is now available on the bulk composition of the sub-mm sized spherules (Misra et al. in Meteorit Planet Sci 7:1001–1018, 2009), almost no idea exists on the latter two varieties. Here, we presented the microprobe data on major oxides and a few trace elements (e.g. Cr, Ni, Cu, Zn) of mm-sized impact spherules in unravelling their petrogenetic evolution. The mm-sized spherules are characterised by homogeneous glassy interior with vesicular margin in contrast to an overall smooth and glassy-texture of the sub-mm sized spherules. Undigested micro-xenocrysts of mainly plagioclase, magnetite and rare clinopyroxene of the target basalt are present only at the marginal parts of the mm-sized spherules. The minor relative enrichment of SiO₂ (~3.5 wt% in average) and absence of schlieren structure in these spherules suggest relatively high viscosity of the parent melt droplets of these spherules in comparison to their sub-mm sized counterpart. Chemically homogeneous mm-sized spherule and impact-melt bomb share similar bulk chemical and trace element compositions and show no enrichment in impactor components. The general depletion of Na₂O within all the Lonar impactites was resulted due to impact-induced volatilisation effect, and it indicates the solidification temperature of the Lonar impactites close to 1,100 °C. The systematic geochemical variation within the mm-sized spherules (Mg# ~0.38–0.43) could be attributed to various level of mixing between plagioclase-dominated impact melts and ultrafine pyroxene and/or titanomagnetite produced from the target basalt due to impact. Predominance of schlieren and impactor components (mainly Cr, Ni), and nearly absence of vesicles in the sub-mm sized spherules plausibly suggest that these quenched liquid droplets could have produced from the impactor-rich, hotter (~1,100 °C or more) central part of the plume, whereas the morpho-chemistry of the mm-sized spherules induces their formation from the relatively cool outer part of the same impact plume.     

X-ray afterglow of GRB 050712: multiple energy injections into the external shock

As indicated by observed X-ray flares,a great amount of energy can be intermittently released from the postburst central engine of gamma-ray bursts(GRBs).As a natural consequence,the GRB’s external shock could be repeatedly energized.With such a multiple energy injection model,we explore the unique X-ray afterglow light curve of GRB 050712,which exhibits four shallow decay plateaus.Together with three early X-ray flares,the central engine of GRB 050712 is believed to have released energy at least seven times after the burst.Furthermore,we find that the energies released during the four plateaus are all on the same order of magnitude,but the luminosity significantly decreased with time.These results may provide some interesting implications for the GRB central engine.     

Research on method of pressure grouting piling of driven tube

The pressure grouting pile of driven tube can improve the load bearing capacity of the single pile from the mechanism of pressure grouting pile of driven tube.On the basis of analyzing the mechanism,the authors designed the machines and tools of pressure grouting,determined the operating manufacture and technology parameter on the pressure grouting secondly.The result shows that the pressure grouting pile of driven tube not only changes the pile type but also reduce the length of the pile and its engineering cost,it enhances the load bearing capacity of single pile an the same time.     

The grain-size characteristics of Quaternary deposits at Xingshan near Siping in Jilin province, China

This research paper analyses the grain-size characteristics of the Quaternary deposits at Xingshan near Siping, Jilin province in China by employing graphic measures to study the grain size distribution and its mode of transport and deposition. The Quaternary deposits at Xingshan lie unconformable on Cretaceous rocks made of siltstone, mudstone and sandstone. The average grain size is between 8.06 to 8.55Ф （0. 002 6 0. 003 7 mm）. The Quaternary deposits at Xingshan mainly compose of very fine silt to clay. The compositions of the grade are clay 63 % and silt 37 %. The clay size components are weathered debris transported and deposited by flowing water from the SE highlands or hills to the low lying NW Xingshan plains whereas the silty components accumulated by aoelian process. The Quaternary deposits at Xingshan accumulated in the middle and late Pleistocene interglacial periods from （459.12 - 39.03 ） ka to （88.92 - 7.56 ） ka. The standard deviation ranged from 0.96 to 1.36%, indicating that the sediments are moderately to poorly sorted, Coefficient of skewness ranged from 0.16 - 0.31 with an average skewness of 0. 218, （Positively skewed towards fine）. Kurtosis values （0.84- 1.05） from the grain size distribution and visual inspection of the frequency curves indicate platykurtic to mesokurtic curves and unimodal to bimodal grain-size distribution. The type of deposit formation is sand dune and the source is at a distal from its provenance.