Tectonometamorphic evolution of the Himalayan metamorphic core between the Annapurna and Dhaulagiri, central Nepal

The metamorphic core of the Himalaya in the Kali Gandaki valley of central Nepal corresponds to a 5-km-thick sequence of upper amphibolite facies metasedimentary rocks. This Greater Himalayan Sequence (GHS) thrusts over the greenschist to lower amphibolite facies Lesser Himalayan Sequence (LHS) along the Lower Miocene Main Central Thrust (MCT), and it is separated from the overlying low-grade Tethyan Zone (TZ) by the Annapurna Detachment. Structural, petrographic, geothermobarometric and thermochronological data demonstrate that two major tectonometamorphic events characterize the evolution of the GHS. The first (Eohimalayan) episode included prograde, kyanite-grade metamorphism, during which the GHS was buried at depths greater than c. 35 km. A nappe structure in the lowermost TZ suggests that the Eohimalayan phase was associated with underthrusting of the GHS below the TZ. A c. 37 Ma ⁴⁰Ar/³⁹Ar hornblende date indicates a Late Eocene age for this phase. The second (Neohimalayan) event corresponded to a retrograde phase of kyanite-grade recrystallization, related to thrust emplacement of the GHS on the LHS. Prograde mineral assemblages in the MCT zone equilibrated at average T =880 K (610 °C) and P =940 MPa (=35 km), probably close to peak of metamorphic conditions. Slightly higher in the GHS, final equilibration of retrograde assemblages occurred at average T =810 K (540 °C) and P=650 MPa (=24 km), indicating re-equilibration during exhumation controlled by thrusting along the MCT and extension along the Annapurna Detachment. These results suggest an earlier equilibration in the MCT zone compared with higher levels, as a consequence of a higher cooling rate in the basal part of the GHS during its thrusting on the colder LHS. The Annapurna Detachment is considered to be a Neohimalayan, synmetamorphic structure, representing extensional reactivation of the Eohimalayan thrust along which the GHS initially underthrust the TZ. Within the upper GHS, a metamorphic discontinuity across a mylonitic shear zone testifies to significant, late- to post-metamorphic, out-of-sequence thrusting. The entire GHS cooled homogeneously below 600–700 K (330–430 °C) between 15 and 13 Ma (Middle Miocene), suggesting a rapid tectonic exhumation by movement on late extensional structures at higher structural levels.     

铜陵地区中酸性侵入岩年代学研究

本文选择了铜陵地区主要岩石类型的代表性岩体中黑云母为测定对象，准确地测定了侵入岩的４０Ａｒ／３９Ａｒ同位素年龄。测定结果表明，区内侵入岩的年龄均小于１４０Ｍａ，属燕山晚期的产物，后期热事件为成矿时代，晚于岩浆侵入时代，在此基础上，分析了ＫＡｒ法、ＲｂＳｒ法同位素年龄产生偏差的原因     

超灵敏加速器质谱计测定^32Si样品制备新技术

介绍了制备元素硅的一种化学方法，它可用于ＡＭＳ装置的离子源。含硅的物质溶解在ＨＦ中，用ＬｉＡｌＨ４把ＳｉＦ４还原成ＳｉＨ４，再将ＳｉＨ４加热分解成元素硅，并且沉淀在石墨盘上，用ＡＭＳ测定ｗ３２Ｓｉ／ｗＳｉ总比值，其灵敏度可达１０＾－１３。     

中国东部6区域近1000年干湿序列的重建和气候跃变分析

本文利用我国的历史气候记载，为东部6区域重建了最近1033年的时间分辨率为1年的区域于湿气候序列，讨论其可靠性，并分析其变化的准周期性和跃变特征。跃变分析采用移动t检验方法，分析各区域干湿气候的世纪尺度和10～20年尺度的跃变现象，辨识跃变信号的参考年代，指出北方各区域的跃变趋势相同，但有时与长江下游地区相反，以及跃变信号在寒冷气候背景下较多出现等特点。     

Accretion and exhumation at a Variscan active margin, recorded in the Saxothuringian flysch

The Saxothuringian flysch basin, on the north flank of the Central European Variscides, was fed and eventually overthrust by the northwestern, active margin of the Tepla-Barrandian terrane. Clast spectra, mineral composition and isotopic ages of detrital mica and zircon have been analyzed in order to constrain accretion and exhumation of rocks in the orogenic wedge. The earliest clastic sediments preserved are of early Famennian age (ca. 370?Ma). They are exposed immediately to the NW of the suture, and belong to the par-autochthon of the foreland. Besides ultramafic (?ophiolite) material, these rocks contain clasts derived from Early Paleozoic continental slope sediments, originally deposited at the NW margin of the Saxothuringian basin. These findings, together with the paleogeographic position of the Famennian clastics debris on the northwestern passive margin, indicate that the Saxothuringian narrow ocean had been closed by that time. Microprobe analyses of detrital hornblendes suggest derivation from the “Randamphibolit” unit, now present in the middle part of the Saxothuringian allochthon (Münchberg nappes). Detrital zircons of metamorphic rocks formed a little earlier (ca. 380?Ma) indicate rapid recycling at the tectonic front. The middle part of the flysch sequence (ca. early to middle Viséan), both in the par-autochthon and in the allochthon, contains abundant clasts of Paleozoic rocks derived from the northwestern slope and rise, together with debris of Cadomian basement, 500-Ma granitoids and 380?Ma (early Variscan) crystalline rocks. All of these source rocks were still available in the youngest part of the flysch (c. middle to late Viséan), but some clasts record, in addition, accretion of the northwestern shelf. Our findings permit deduction of minimum rates of tectonic shortening well in excess of 10–30?mm per year, and rates of exhumation of ca. 3?mm/a, and possibly more.     

RS和GIS结合的初步尝试

通过对航空遥感图像物体特征（色调、形状、大小、阴影、纹理及其相互关系）的提取，采用人机交互和自动识别的方法进行遥感航片的综合分析和利用，是合肥市规划与建设管理信息系统的一个重要内容。ＡＲＣ／ＧＲＩＤ模块的优势在于一对于栅格数据进行显示和查询；对于栅格数据进行算术、逻辑、关系、赋值等操作；对数据进行管理；其分析功能很强，可进行环境分析、社会分析、水文分析、经济分析；建立模型。通过图象分类处理，可将城市绿化、江河、城市主干道、建筑物分类，并对城市绿化进行区域统计，对江河、日照进行分析和对所分割的地块进行检索分析     

Solar modulation of cosmogenic nuclide production over the last millennium: comparison between C and Be records

For about the last 30 years it has been recognized that the high frequency component of the tree rings ¹⁴C/¹²C record is dominated by the modulation of the cosmic ray flux by the solar wind. In particular, it has been demonstrated that the three most recent periods of low sunspot occurrence were characterized by high values of atmospheric ¹⁴C/¹²C. During the last millennium other periods of high ¹⁴C/¹²C values were observed but their solar origin is still debatable. In the present work we compare these fluctuations with an independent record of cosmogenic ¹⁰Be measured in ice from the South Pole to check the solar origin of the observed ¹⁴C/¹²C variations. In order to compare quantitatively the results obtained on ¹⁰Be and ¹⁴C, it is necessary to take into account the different behaviour of these two cosmogenic isotopes, and especially the damping effect of the carbon cycle in the case of ¹⁴C. As an input to a 12-box numerical model we used the relative fluctuations of the ¹⁰Be concentrations record measured in South Pole ice and converted it into a synthetic ¹⁴C record. We took into account the fact that ¹⁰Be modulation is enhanced in polar regions due to the orientation of the geomagnetic field. As expected, the fluctuations of the modelled ¹⁴C record are much smaller (a factor of 20) than those observed for the raw ¹⁰Be record. In addition, the variations are smoother and shifted in time by a few decades. The ¹⁰Be-based ¹⁴C variations closely resemble the ¹⁴C measurements obtained on tree rings (R = 0.81). In particular, it is easy to identify periods of maximal ¹⁴C/¹²C which correspond to solar activity minima centred at about 1060, 1320 (Wolf), 1500 (Spörer), 1690 (Maunder) and 1820 (Dalton) yr A.D. Cross-correlation calculations suggest that there is no significant lag between the ¹⁰Be-based ¹⁴C and the tree-ring ¹⁴C records. Our study strongly suggests the dominance of the solar modulation on the cosmonuclide production variations during the last millennium.     

40Ar/39Ar geochronology and exhumation of mylonitized metamorphic complex in Changle-Nanao ductile shear zone

New⁴⁰Ar/³⁹Ar plateau ages from rocks of Changle-Nanao ductile shear zone are 107.9 Ma(Mus), 108.2 Ma(Bi), 107.1 Ma(Bi), 109.2 Ma(Hb) and 117.9 Ma(Bi) respectively, which are concordant with their isochron ages and record the formation age of the ductile shear zone. The similarity and apparent overlap of the cooling ages with respective closure temperatures of 5 minerals document initial rapid uplift during 107–118 Ma following the collision between the Min-Tai microcontinent and the Min-Zhe Mesozoic volcanic arc. The⁴⁰Ar/³⁹ Ar plateau ages, K-Ar date of K-feldspar and other geochronologic information suggest that the exhumation rate of the ductile shear zone is about 0.18–1.12 mm/a in the range of 107–70 Ma, which is mainly influenced by tectonic extension.     

电法勘探的发展和展望

电法勘探在经历了近一个世纪的发展后，其方法理论、仪器设备、野外数据采集、处理和解释等方面都经历了一系列重大变化．本文以方法理论的进展为主线，回顾、展望了目前电法勘探中几个重要而令人关注的研究焦点．这些问题的研究进展将会对21世纪的电法勘探产生深远的影响．     

日地水文学与灾害预测

研究地球水文变化的日地物理成因和规律的日地水文学（Solar-TerrestrialHydrology），用于水、旱灾害预测多次获得证实.本文从日地水文物理基础、长江淮河22年周期性大洪水、黄河大洪水和太阳活动关系、太阳活动双重衰减期北方大旱、17世纪日地水文异常变化、太阳活动对暴雨洪水中短期影响、台湾海峡两侧大暴雨洪水落区转移、全球最大洪水日地水文研究以及学科发展和应用前景九个方面，对中国近70多年来的主要成果加以回顾和总结.基础科学、高科技和应用紧密结合，促成对国民经济发展直接相关的新学科，是当代科学进步的一个显著标志，这里又是一个例证．