论龙门山中北段东缘印支运动晚幕的性质

对龙门山中北段东缘地区印支运动晚幕的性质有两种看法,即褶皱运动和局部上升运动。经对该次构造事件之不整合的性质再研究后,认为其为一次掀斜运动。形成该掀斜运动的机制为从晚三叠世晚期至中侏罗世中期区域水平挤压力减小而引起龙门山前陆盆地岩石圈均衡回返上升。     

福建武夷山2个典型植物群落建群种的热值研究

研究了福建武夷山自然保护区2个典型植物群落一甜槠群落(Castanopsis eyrei community)和黄山松群落(Pinus taiwanensis community)建群种的热值和灰分含量,以及凋落物热值的季节变化.结果表明:(1)2个建群种甜槠和黄山松各器官的灰分含量、干重热值和去灰分热值因种而异,同种植物不同器官之间灰分含量和热值存在差异.甜槠各器官灰分含量在0.69%～4.09%之间,干重热值在17.06～20.28kJ/g之间,去灰分热值在17.46～21.00kJ/g 之间;黄山松各器官灰分含量在0.58%～3.14%之间,干重热值在16.27～22.14kJ/g之间,去灰分热值在16.60～22.58kJ/g之间.(2)甜槠和黄山松凋落物热值的季节变化存在差异.(3)林地残留物的干重热值与年凋落物的干重热值相比,呈现了下降的趋势.     

Characteristics and geological significance of the eclogites from the Tongbai Mountains, Henan Province

Some eclogites and the related high-P metamorphic belt have been found for the first time from the Tongbai Mountains, Henan Province, where the eclogites and their probable retrogressive products ——garnet amphibolites——occur as lenses in mica-schists. The fresh eclogites comprise garnet, omphacite, quartz, rutile, phengite, barroisite, etc. The compositional features of garnet and available geothermobarometers indicated that the eclogites belong to the low-T type. The mica-schists contain phengite, quartz, garnet and rutile that are also attributed to high-P assemblage. The eclogites and related high-P belt probably belong to the Early Paleozoic in age, which is distinct from the Indosinian Dabie high- and ultrahigh-P metamorphic belt.     

使用 MiVnt图像分析系统进行树木 年轮细胞特征研究的尝试

以芦芽山白杄(Picea meyeri)的树轮样本作为对象,尝试使用MiVnt图像分析系统观测树轮细胞特征.建立了包含树轮宽度、细胞数目、细胞大小、最大细胞大小、最小细胞大小、早材细胞数目、晚材细胞数目在内的7个树轮年表.结果表明,树轮宽度、细胞数目和早材细胞数目年表具有较高的气候信息质量.晚材细胞数目年表与其余年表之间具有负相关关系,表明细胞特征可以体现与树轮宽度不同的气候信息.除晚材细胞数目年表外,其余年表均与生长季气温呈负相关,与降水呈正相关,体现了土壤干旱对树木生长的限制.晚材细胞数目年表与生长季末期的降水显著负相关,体现了生长季末期气候条件对形成层细胞的影响.本文是研究树木生长与气候因子关系的有益补充.     

马松岭铜矿区变火山-沉积岩系形成环境研究

在搜集前人相关测试数据,对龙门山中段马松岭矿区出露广泛的变火山岩及其准同期变辉绿岩、赋矿火山-沉积围岩进行补充采样和测试基础上,通过岩石地球化学研究,认为马松岭矿区变火山-沉积岩系主体为变岛弧钙碱系列,含少量变大洋岛碱性玄武岩和变正常沉积岩,形成环境为张裂岛弧;彭州式铜矿可能是在VMS型矿胚基础上经后期改造而成;与火山沉积岩系准同期的变辉绿岩为岛弧拉斑系列,因受到不断成熟的过渡壳物质混杂,而主体显高铝系列特征。     

S-wave velocity of the crust around Tianshan Mountains inverted from seismic ambient noise tomography

We process ambient noise data from seismic stations deployed in central Asia to determine the crustal shear wave velocity structure beneath the Tianshan Mountians and surrounding area. About 748 inter-station Rayleigh wave empirical Green’s functions have been recovered to estimate the phase velocity dispersions over periods from 6 to 50 s using the image transformation technique. Results show that for short periods (6–20 s), the distribution of Rayleigh wave phase velocities is generally consistent with surface geology, with high velocities corresponding to mountain ranges and low velocities to sedimentary basins. Along two profiles, which trend from NE-SW and NW-SE, the shear wave velocity shows a pair of high velocity anomalies dipping in opposite directions beneath the Tianshan Mountains. At shallow depths, those high velocity anomalies roughly correlate with areas where the mountain front and the surrounding basin are connected. The profiles also show a narrow zone beneath the Tianshan Mountains, which may represent a route for the upwelling from upper mantle. Those observations suggest that the underthrusting of the Tarim Basin and Kazakh Shield combine with the weakness of the crust, which is heated by the upwelling from upper mantle, may play an important role on the reactivation of the Tianshan Mountains associated with the India-Eurasia collision.     

Late Pleistocene glaciation of the Changbai Mountains in northeastern China

The Changbai Mountains （2749 m a.s.l.） in northeastern China are one of the typical mountain regions with glaciation since late Pleistocene as evidenced by well-preserved erosive and accumulative landforms at elevations above 2000 m a.s.l, formed by glaciers around the crater lake, Tianchi Lake. Cirque glaciers developed on both the inner and outer sides of the volcanic cone. Well-preserved cirques, glacial trough valleys, glacial threholds, polished surfaces of the glacial erratics and the moraine ridges indicate that several glaciation processes took place during the last glacial period in this region. Resuits of optically stimulated luminescence （OSL） dating on the moraine sediments, and the K/Ar, thermal ionization mass spectrometry （TIMS）, electronic spinning resonance （ESR） dating on the volcanic rocks suggest two periods of glacier advances. One is named the Black Wind Mouth glacier advance taking place on the west and north slopes of the volcanic cone at an elevation of 2000-2100 m a.s.l., which is dated to about 20 ka, being the result of the Last Glacial Maximum （LGM）. The other is named the Meteorological Station glacier advance at the elevation of 2400-2600 m a.s.l., dated to 11 ka during the late glacial period, and is tentatively correlated to the Younger Dryas stage. The scope of the former glacier advance is larger than that of the latter. Regional comparisons showed that the glacial sequences in the Changbai Mountains are similar to other glaciated areas in eastern Asia during the later part of the last glacial cycle.     

汶川地震的地表破裂与逆冲-走滑作用

2008年5月12日在龙门山映秀-北川断裂带发生的8.0级特大地震,属于逆冲-走滑型地震.作者以地表破裂为切入点,在映秀-北川断裂和彭灌断裂的关键部位,对断错山脊、洪积扇、河流阶地、边坡脊、断层陡坎、河道锴断、冲沟侧缘壁位错、小路位错、公路位错、公路拱曲、构造裂缝、断层偏转、擦痕、挤压脊、坡中槽等汶川地震所导致的地表破裂和断裂带开展了详细的野外地貌测量,标定了映秀-北川断裂带和彭灌断裂的垂向断距和水平断距,结果表明汶川地震的地表破裂带沿北东东向延伸,走向介于NE30°～50°之间,倾向北西,倾角介于30°～40°之间.其中北川-映秀断裂带的破裂带从映秀向北东延伸达180～190 km,属于单侧多点破裂型,以逆冲-右行走滑为特点,垂直位错为1.60～6.00 m,水平位错为0.20～6.50 m;彭灌断裂的地表破裂出露于彭州磁蜂场-绵竹汉旺之间,长度为30～40 km,以逆冲-右行走滑为特点,垂直位错为0.39～2.00 m之间,水平位错为0.20～0.70 m.表明该地震地表破裂带存在逆冲运动分量和右行走滑运动分量,逆冲运动分量略大于或等于右行走滑运动分量.根据历史地震和活动构造地貌的年龄测定资料,作者认为该区单条断裂的强震复发间隔在1～3ka.在此基础上,初步编制了龙门山地区的地质动力模型图,并认为下地壳物质在龙门山的近垂向挤出和垂向运动,导致了龙门山断裂带的向东逆冲运动、龙门山构造带抬升和汶川特大地震.     

龙门山巨型滑覆型飞来峰体系与龙门山构造活动性

广泛分布于龙门山推覆构造带前缘的飞来蜂群构成规模巨大的飞来蜂体系,其平面展布和构造线方向与龙门山推覆构造一致,但构造倒向与龙门山推覆构造相反.其明显构造特征表明为滑覆作用形成,并且与龙门山构造演化密切相关,主要形成于喜马拉雅期.龙门山收缩变形的继续发展对飞来峰产生叠加变形,中央断裂可截覆飞来蜂,反映了龙门山构造带具有很强的新构造活动性.