Evolution of an englacial volcanic ridge: Pillow Ridge tindar, Mount Edziza volcanic complex, NCVP, British Columbia, Canada

Glaciovolcanic deposits are critical for documenting the presence and thickness of terrestrial ice-sheets, and for testing hypotheses about inferred terrestrial ice volumes based on the marine record. Deposits formed by the coincidence of volcanism and ice at the Mount Edziza volcanic complex (MEVC) in northern British Columbia, Canada, preserve an important record for documenting local and possibly regional ice dynamics. Pillow Ridge, located at the northwestern end of the MEVC, formed by ice-confined, fissure-fed eruptions. It comprises predominantly pillow lavas and volcanic breccias of alkaline basalt composition, with subordinate finer-grained volcaniclastic deposits and dykes. The ridge is presently  4 km long,  1000 m in maximum width, and  600 m high. Fifteen syn- and post-eruptive lithofacies are recognized in excellent exposures along the glacially dissected western side of the ridge. We recognize five lithofacies associations: (1) poorly sorted tuff breccia and dykes, (2) proximal pillow lava, dykes and tuff breccia, (3) distal pillow lava, poorly sorted conglomerate and well-sorted volcanic sandstone, (4) interbedded tuff, lapilli tuff, and tuff breccia units, and (5) heterolithic volcanogenic conglomerate and sandstone. Given the abundance of pillow lavas and the lack of surrounding topographic barriers capable of impounding water, we agree with Souther [Souther, J.G., 1992. The late Cenozoic Mount Edziza volcanic complex. Geol. Soc. Can. Mem., vol. 420. 320 pp] that the bulk of the edifice formed while confined by ice, but have found evidence for a more complex and variable eruption history than that which he proposed. Preliminary estimates of water-ice depths derived from FTIR analyses of H₂O give ranges of 300 to 680 m assuming 0 ppm CO₂, and 857 to 1297 m assuming 25 ppm CO₂. Variations in depth estimates among samples may indicate that water/ice depths changed during the evolution of the ridge, which is consistent with our interpretations for the origins of different lithofacies associations. Given that the age of the units are likely to be ca. 0.9 Ma [Souther, J.G., 1992. The late Cenozoic Mount Edziza volcanic complex. Geol. Soc. Can. Mem., vol. 420. 320 pp], Pillow Ridge may be the best documentation of a regional high stand of the Cordilleran Ice Sheet (CIS) in the middle Pleistocene, and an excellent example of the lithofacies and stratigraphic complexities produced by variations in water levels during a prolonged glaciovolcanic eruption.     

我国典型海洋型冰川区高海拔区输出水量变化对气候变暖的响应

通过丽江盆地气象水文观测资料研究发现: 冰雪消融加剧、融水增加, 漾弓江流域径流量明显上升; 高海拔冰雪区消融期提前, 春季径流增加明显; 高海拔冰雪区的径流输出对漾弓江流域水量平衡的贡献量逐年增加, 体现了全球气候变暖背景下高海拔冰雪区对整个流域水循环的重要性.对海螺沟流域实测气象水文资料的分析也表明, 气候变暖背景下, 该流域冰雪区水量输出也逐年上升.两流域高海拔区输出水量的剧烈增加, 明显响应了气候变暖, 表明了流域水循环的加速, 这必然将对区域的发展和资源开发产生重要影响.      

泰山玉皇顶三维可视化系统的设计与实现

根据泰山玉皇顶景点的特征,结合现有的地形图、遥感影像和实地调查资料数据,运用三维建模软件和多源数据融合等技术,研发了基于VRM ap的三维可视化系统,为玉皇顶景点的宣传、保护和管理提供了三维的、具有沉浸感的交互平台,从而更好地为旅游管理人员和广大游客服务。     

青藏高原东南缘晚渐新世-早中新世中下地壳流动:滇西瑶山与玉龙变质杂岩构造解析

通常认为位于青藏高原东南缘的巽他地块侧向刚性块体挤出调节了印度-欧亚板块碰撞及后碰撞。然而,最近的研究表明,低粘度的中下地壳流动可以解释青藏高原向外扩张的现象。关于哪种机制在巽他地块挤出过程中起着主导作用仍未解决。在本研究中,我们重点围绕哀牢山-红河构造带南部的瑶山杂岩以及构造带北部邻区的玉龙杂岩开展构造研究。详细的宏观构造解析、显微构造以及组构分析说明切向剪切作用在瑶山与玉龙穹隆的形成与剥露中起着重要作用,组成穹窿的岩石均具有分层流变学特点。瑶山穹隆是发育在较深岩石层位的穹隆构造,而玉龙穹隆是发育在较浅岩石层位的穹隆构造。向南或东南切向剪切可能是上地壳向南的重力滑动和粘滞下地壳相对中上地壳向北流动共同作用的结果。前者可能与高原重力塌陷有关,但后者的驱动力有待进一步研究。     

Crustal structure beneath the Mount Cameroon region derived from recent gravity measurements

In this study, the recent update of the gravity database with new measurements has raised the opportunity of improving the knowledge of the crustal structure beneath the large volcanic system called Mount Cameroon, and its implication in the regional tectonics. The multi-scale wavelet analysis method was applied to highlight the geologic features of the area, and their depths were estimated using the logarithmic power spectrum method. The results reveal a complex crustal structure beneath Mount Cameroon with high variation in the lateral distribution of crustal densities. The upper and lower crusts are intruded by dense materials originating from the mantle with less lateral extension. The trends of Tiko and Ekona faults along the intrusion suggest tectonic activities as deep as 25 km. The difference in mantle composition or temperature between the East and the West of the studied area is clearly seen in detailed wavelet images and agrees with a mantle origin for the Cameroon Volcanic Line.     

山区居民对气候变化及其影响与适应的感知分析——以玉龙雪山地区为例

通过问卷调查和访谈,揭示了青藏高原东南缘玉龙雪山地区居民对当地气候变化及其影响与适应的感知认识。结果表明：居民对玉龙雪山地区气候变化的感知强度与科学研究结果总体上具有很高的一致性。居民对气候变化对农业环境影响的感知不很强烈,认为气候变化并未影响到农作物长势和产量,但对气候变化导致农作物病虫害略有增加和作物生长期延长的感知却持较高赞同度。居民对气候变化及其适应的感知强度总体上与海拔高度相关显著,而对气候变化及其影响的感知则与年龄显著相关。气候变化已促使山区居民调整产业结构,发展低耗水农业经济,并积极参与山区旅游、外出打工,以弥补微薄的农业收入。同时,居民也期望政府能够给予他们一定的经济补偿,以弥补由于干旱和倒春寒等带来的经济损失。     

玉龙雪山冰川沉积序列OSL定年

位于青藏高原东南缘的玉龙雪山分布有欧亚大陆纬度最低的海洋型冰川,其主峰及周边地区保存了大量清晰完整的第四纪冰川遗迹。研究该区第四纪冰川作用遗迹及其冰川作用史,具有重要的理论与实际价值。应用光释光（OSL）测年技术对玉龙雪山冰川沉积物进行了定年,结合前人研究资料,重建玉龙雪山冰川作用史。研究结果表明：玉龙雪山东麓的末次冰期冰碛物主要形成于晚更新世末次冰期最盛时期,其平均年代约在25ka,西麓末次冰期冰碛物形成年代约为50ka,对应于深海氧同位素3阶段中期（MIS3b）。而倒数第二次冰期的年代在240ka左右,处于中更新世晚期,对应于MIS8阶段,当时玉龙雪山存在多条复式山谷冰川。该研究可为玉龙雪山第四纪冰川作用历史的重新认识以及光释光测年技术在该区的应用提供基础资料。     

云南玉龙雪山第四纪冰期与冰川演化模式

云南玉龙雪山高峰区有现代冰川１９条,面积１１．６１Ｋｍ＾２,冰川融水汇入金沙江。在现代冰川外围有丰富的古冰川遗迹,可划分３次更新世冰期,即大理、丽江和云杉枰冰期。相当于欧洲阿尔卑斯的玉木里斯和民德冰期。其中以丽江冰期冰川规模最大,当时,河水冰期的白水河冰川长２．５Ｋｍ,冰川 演化模式与梅里雪山、贡嘎山东坡相同,均属藏东南型,而与青藏高原广大高山区以例数第三次冰不川最大规模有别。主要是它们位于青藏高     

藏东玉龙超大型斑岩铜矿床成岩成矿系统时间跨度分析

藏东玉龙超大型斑岩铜矿床是目前西藏发现的最大斑岩铜矿床,含铜岩体主要由早期石英二长斑岩及晚期正长花岗斑岩组成。本文用LA-ICP-MS法测定早期石英二长斑岩及晚期正长花岗斑岩锆石U-Pb年龄及Ar-Ar法测定钾质蚀变带黑云母的Ar-Ar年龄,发现玉龙含矿斑岩体早期石英二长斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.3Ma, MSWD=0.92)与晚期正长花岗斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.2Ma, MSWD=1.24)基本相同,也和黑云母Ar-Ar坪年龄(41.7±0.8Ma)及等时线年龄(41.3±0.8Ma)在误差范围内一致。玉龙斑岩铜矿早期及晚期岩体锆石U-Pb年龄一致表明含矿岩体在地质上的早期及晚期主要是岩浆在较短时间内脉动侵入所致。玉龙含矿岩体锆石U-Pb年龄(封闭温度约800℃)、³⁹Ar-⁴⁰Ar 年龄(封闭温度约300℃)及前人获得的Re-Os年龄40.1±1.8Ma(封闭温度约500℃)在误差范围内基本一致,表明含矿岩体岩体快速冷却,玉龙超大型斑岩铜矿床成岩成矿系统时间跨度小于1Ma。     

西藏玉龙斑岩铜矿床绢云母族蚀变矿物短波红外光谱特征及对勘查的指示意义

玉龙斑岩铜矿晚期绢云母化、黏土化蚀变强烈叠加在早期的钾硅酸盐化带内,模糊了蚀变分带特征及其与铜矿化之间的相关性.利用短波红外光谱(SWIR)可快速识别斑岩铜矿床内含羟基蚀变矿物,根据该类矿物的空间分布特征与矿化的对应关系,指导找矿勘查工作.本文对玉龙铜矿床靠近斑岩体中心的三个钻孔进行了详细的蚀变-矿化编录和SWIR分析...