BOFI断面测量系统在地铁隧道测量中的应用     

卢松耀  陈雪丰 《地理空间信息》2010,8(3):122-124

介绍了基于国产全站仪和PDA的隧道断面测量系统的组成及特点,结合工程案例总结了地铁隧道断面测量的方法,对相关技术人员有较高的参考价值。  相似文献   

Morlet变换在超宽频带地震仪记录的汶川震前数据处理中的应用     

皮誉洋  周云耀  吕永清 《大地测量与地球动力学》2018,38(9):974-978

介绍了Morlet小波变换的基本原理和特点。以汶川地震为例，选取2008-05-01~05-12的地震计垂直向连续波形数据，使用Morlet小波变换得到时频谱。分析时频图发现，在汶川地震发生前的数十h中，0.1~0.2 Hz频段的能量幅值出现明显的递增趋势，是非台风扰动引起的频率异常，与已有论文结论符合良好，证明Morlet小波变换是分析震前频率特征的有效方法。  相似文献   

Integrated garnet and zircon–titanite geochronology constrains the evolution of ultra‐high–pressure terranes: An example from the Sulu orogen     

Da Wang  Jeffrey D. Vervoort  Christopher M. Fisher  Hui Cao  Guangxu Li 《Journal of Metamorphic Geology》2019,37(5):611-631

Dating ultra‐high–pressure (UHP) metamorphic rocks provides important timing constraints on deep subduction zone processes. Eclogites, deeply subducted rocks now exposed at the surface, undergo a wide range of metamorphic conditions (i.e. deep subduction and exhumation) and their mineralogy can preserve a detailed record of chronologic information of these dynamic processes. Here, we present an approach that integrates multiple radiogenic isotope systems in the same sample to provide a more complete timeline for the subduction–collision–exhumation processes, based on eclogites from the Dabie–Sulu orogenic belt in eastern China, one of the largest UHP terranes on Earth. In this study, we integrate garnet Lu–Hf and Sm–Nd ages with zircon and titanite U–Pb ages for three eclogite samples from the Sulu UHP terrane. We combine this age information with Zr‐in‐rutile temperature estimates, and relate these multiple chronometers to different P–T conditions. Two types of rutile, one present as inclusions in garnet and the other in the matrix, record the temperatures of UHP conditions and a hotter stage, subsequent to the peak pressure (‘hot exhumation') respectively. Garnet Lu–Hf ages (c. 238–235 Ma) record the initial prograde growth of garnet, while coupled Sm–Nd ages (c. 219–213 Ma) reflect cooling following hot exhumation. The maximum duration of UHP conditions is constrained by the age difference of these two systems in garnet (c. 235–220 Ma). Complementary zircon and titanite U–Pb ages of c. 235–230 Ma and c. 216–206 Ma provide further constraints on the timing of prograde metamorphism and the ‘cold exhumation' respectively. We demonstrate that timing of various metamorphic stages can thus be determined by employing complementary chronometers from the same samples. These age results, combined with published data from adjacent areas, show lateral diachroneity in the Dabie–Sulu orogeny. Three sub‐blocks are thus defined by progressively younger garnet ages: western Dabie (243–238 Ma), eastern Dabie–northern Sulu (238–235 Ma) and southern Sulu terranes (225–220 Ma), which possibly correlate to different crustal slices in the recently proposed subduction channel model. These observed lateral chronologic variations in a large UHP terrane can possibly be extended to other suture zones.  相似文献   

Ultra‐high temperature metamorphism recorded in Fe‐rich olivine‐bearing migmatite from the Khondalite Belt,North China Craton          下载免费PDF全文

Cyril Lobjoie  Wei Lin  Pierre Trap  Philippe Goncalves  Qiuli Li  Didier Marquer  Olivier Bruguier  Arnaud Devoir 《Journal of Metamorphic Geology》2018,36(3):343-368

We document the first occurrence of Fe‐rich olivine‐bearing migmatitic metapelite in the Khondalite Belt, North China Craton. Petrological analyses revealed two exotic assemblages of orthopyroxene+spinel+olivine and orthopyroxene+spinel+cordierite. Phase relation modelling suggests that these assemblages are diagnostic of ultra‐high temperature (UHT) metamorphism in the Fe‐rich system, with temperatures from 1,000 to 1,050°C at 0.6 GPa. U–Th–Pb SIMS analyses on zircon reveal a similar age of c. 1.92 Ga for the olivine‐bearing migmatite and an adjacent gabbronoritic intrusion that is therefore identified as the heat source for the UHT metamorphism. These results, coupled with additional analysis of the famous Tuguiwula sapphirine‐bearing granulite, lead to a re‐appraisal of the P–T path shape and heat source for the UHT metamorphism. We suggest that UHT metamorphism, dated between 1.92 and 1.88 Ga, across the whole Khondalite belt, proceeded from a clockwise P–T evolution with an initial near‐isobaric heating path at ~0.6–0.8 GPa, and a maximum temperature of 1,050°C followed by a cooling path with minor decompression to ~0.5 GPa. Considering our results and previous works, we propose that the orogenic crust underwent partial melting at temperature reaching 850°C and depth of ~20 to ~30 km during a period of c. 30 Ma, between 1.93 and 1.90 Ga. During this time span, the partially molten crust was continuously intruded by mafic magma pulses responsible for local greater heat supply and UHT metamorphism above 1,000°C. We propose that the UHT metamorphism in the Khondalite belt is not related to an extensional post‐collisional event, but is rather syn‐orogenic and associated with mafic magma supplies.  相似文献   

超深涌水钻孔的钻探工艺及水文地质试验方法研究     

李建平 《中国煤炭地质》2012,(1):32-34,44

C4Z—G-05孔为某铁路高黎贡山隧道工程勘察钻孔,钻孔深度1075．5m。钻探过程中分别在孔深288～400m和611～724m穿过落差大于100m的断裂构造破碎带,并出现涌水及漏水现象,施工难度大,水文地质试验难以进行。据此,采取了合理的施工顺序,并根据钻进时的机械设备及钻进情况及时调控钻进参数;针对不同的地层,选用不同的泥浆类型,从而顺利的完成了该孔钻探工作。在水文地质试验中,对松散层潜水,采取了抽水试验,对两个断裂带,适时的运用观测涌水量和压力水头及涌水试验的方法,并选择适宜的计算公式,较好的完成了该孔的水文地质参数的计算工作．取得了良好的效果。  相似文献   

A New Single Vacuum Furnace Design for Cosmogenic 3He Dating     

Laurent Zimmermann  Pierre Henri Blard  Pete Burnard  Sarah Medynski  Raphael Pik  Nicolas Puchol 《Geostandards and Geoanalytical Research》2012,36(2):121-129

Helium‐3 is a stable cosmogenic isotope that can be used to determine the time interval during which a rock sample has been at or close to the Earth’s surface. As a result of the high production rate of ‘cosmogenic’³He (≈ 130 at g^?1 year^?1) and the low detection limit of modern mass spectrometers, it is possible to date exceptionally young surfaces (≈ 1000 years). The precision and accuracy of cosmogenic ³He measurements depend critically on the passive helium blank (produced by the metalwork of the extraction furnace) which can be significant relative to the sample signals. We have developed and constructed, at the CRPG (Nancy, France), a new high temperature furnace (< 1500 °C) to extract helium in minerals such as apatite, pyroxene and olivine at 1050, 1350 and 1450 °C, respectively. The furnace demonstrated an excellent helium extraction yield (> 99% for olivine and pyroxene for heating times of 20–30 min and temperatures in the range 1050–1450 °C) and low residual helium contributions (the blank, obtained under the same analytical conditions as for sample extraction: 1 × 10^?15 mole ⁴He and < 4 × 10^?21 mole ³He). This is approximately an order of magnitude lower than those reported by other laboratories using conventional furnaces.  相似文献   

The fate of zircon during UHT–UHP metamorphism: isotopic (U/Pb, δ18O,Hf) and trace element constraints          下载免费PDF全文

J. Kotková  M. Whitehouse  U. Schaltegger  F.‐X. D'Abzac 《Journal of Metamorphic Geology》2016,34(7):719-739

Garnet–clinopyroxene ultra‐high‐pressure (UHP) rocks from the northern Bohemian Massif contain zircon with micro‐diamond inclusions. Trace element concentrations, oxygen and hafnium isotopic composition and U–Pb age of distinct textural domains in zircon characterize their growth conditions and temporal evolution. Diamond‐bearing zircon mantle domains with relicts of oscillatory zoning have uniform Th/U ratios (~0.1–0.2), high‐Ti contents (110–190 ppm, corresponding to temperatures of at least 1100 °C), and some (two of 17 mantle analyses) preserve steep heavy rare earth element (HREE) patterns with Yb_N/Gd_N = 10–11, with a weak negative Eu anomaly. These signatures are consistent with crystallization from a melt under UHP/ultra‐high‐temperature (UHT) conditions. Some of the bright‐cathodoluminscence (CL) rims preserve Th/U and Ti values characteristic of the zircon mantles, but others show elevated Th/U ratios of ~0.3–0.4 and lower Ti contents (20–40 ppm; only 13 ppm in a rare low‐CL outer rim). As they feature flat HREE patterns and negative Eu anomalies and commonly make embayments and truncate the mantle zoning, we suggest that they have formed through recrystallization in the solid state during exhumation of the rock, when both garnet and plagioclase were stable. The three zircon domains, that is, cores, mantles and rims, yield U–Pb concordia ages of 340.9 ± 1.5, 340.3 ± 1.5 and 341.2 ± 3.4 Ma respectively. When linked to the previously reconstructed P–T path of the rock, the error limits of the zircon mantle and rim ages constrain the exhumation of the rocks from depth of ~140 km (UHP) to ~80 km (HP) to a minimum rate of 1.5 cm yr^?1. The zircon cores are heterogeneous in terms of Th/U ratio (below 0.1 but also above 0.2) and REE characteristics, and their εHf values scatter between ?15.7 and +4.8 with similar values for individual domains within a single zircon grain suggesting a very localized control on hafnium isotope composition on a grain scale. The non‐equilibrated εHf values as well as a large range of the Hf‐depleted mantle model ages possibly reflect the presence of a heterogeneous population of old zircon. Consequently, the uniform and young ²³⁸U/²⁰⁶Pb ages may represent (near‐)complete resetting of the U–Pb geochronometer during the UHP–UHT event at c. 340 Ma through dissolution–reprecipitation process. In contrast to Hf, the oxygen isotope composition of zircon is homogeneous, ranging between 7.8‰ and 9.6‰ VSMOW, reflecting a source containing upper crustal material and homogenization at UHP–UHT conditions. Our study documents that continental crust was subducted to mantle depths at c. 340 Ma during the Variscan orogeny and was subsequently very rapidly exhumed, implying that the sequence of events was faster than can be resolved by the secondary ion mass spectrometry technique.  相似文献   

高瓦斯涌水超厚煤系复杂地层的钻进施工          下载免费PDF全文

孙孝刚  王聪  代敏兵  张涛 《探矿工程》2014,41(10):45-49

在瓦斯含量极高的煤层（厚）和不同地层段涌水的超厚水敏性地层中钻进施工,合理设计钻孔结构、选择设备、钻进方法、钻进参数和正确操作,是顺利完成钻进施工的前提,正确使用泥浆是孔内事故预防措施的关键。正确使用“高密度”水基成膜泥浆,既能保持孔内液柱与孔壁之间的压力平衡,也能降失水抑制水敏性地层水化膨胀和分散脱落,从而达到防止孔壁坍塌,起到稳定孔壁的作用。介绍了这些技术措施在贵州扬寨煤矿高瓦斯涌水超厚煤系复杂地层中的应用及效果。  相似文献   

辽西察哈尔山和小欧力营超单元花岗岩地质特征     

迟广城  林维峰 《国土资源》1999,(4)

辽西务欢池-铁匠各冷地区中生代—晚古生代花岗岩岩体可划分为十一个填图单元,据岩体形成时间、侵入接触关系、岩体及岩石组构特征,可把这十一个花岗岩填图单元归并为小欧力营和察哈尔山两个超单元。两个超单元主体岩性为钾长花岗岩和二长花岗岩,岩体成因类型属于壳幔混源型,二者岩源不同。小欧力营超单元同位素年龄为269Ma,侵入时代为早二叠纪,为强力就位;察哈尔山超单元同位素年龄为190Ma,侵位时代为早侏罗纪,岩石糜棱岩化明显,属于被动就位  相似文献   

再生水入渗区典型抗生素分布特征与地下水微生物群落影响因素研究     

郭子宁  王旭升  向师正  胡桐搏  刘菲  关翔宇 《岩矿测试》2022,(3):451-462

再生水入渗携带的抗生素污染是地下水污染的来源之一,已经成为城市地下水资源的安全中不可忽视的问题。抗生素对复杂和脆弱地下水环境中的微生物群落及其功能的影响值得关注。本研究基于利用16S rRNA基因高通量测序方法,对3月和9月两个月份再生水渗入区城市地下水中微生物群落结构进行分析。结合现场调查测试和室内分析,测得样品中离子(K~+、Na~+、Ca²⁺、Mg²⁺、NH~+₄、F~-、Cl~-、SO■、NO~-₃、NO~-₂、HCO~-₃、CO■)浓度,并采用超高效液相色谱-串联质谱技术测得主要的抗生素浓度(环丙沙星、诺氟沙星、氧氟沙星、莫西沙星、磺胺吡啶和磺胺醋酰),对研究区地下水环境中微生物群落结构及与环境因子的响应规律进行探讨。结果表明：(1)研究区内3月份地下水中抗生素浓度要高于9月份整体抗生素浓度,以磺胺醋酰和环丙沙星为主,此外除了季节因素外,人类活动可能是影响抗生素分布的又一因素;(2)微生物群落主要由变形菌门(Proteobacteria,81.0...  相似文献