我国再次发现硒铅矿

本文报道了我国再次在华南6217花岗岩型铀矿床中发现硒铅矿，测定了该矿物的化学成分，结合该铀矿床的矿物组合和成矿物理化学条件，讨论了硒铅矿的生成环境。     

Sr isotope evolution during chemical weathering of granites -- impact of relative weathering rates of minerals

The Sr isotopic systematics in the weathering profiles of biotite granite and granite porphyry in southern Jiangxi Province were investigated. The results showed that during the chemical weathering of granites, remarked fractionation occurred between Rb and Sr. During the early stages of chemical weathering of granites, the released Sr/Si and Sr/Ca ratios are larger than those of the parent rocks, and the leaching rate of Sr is higher than those of Si, Ca, K, Rb, etc. Dynamic variations in relative weathering rates of the main Sr-contributing minerals led to fluctuation with time in 87Sr/86Sr ratios of inherent and released Sr in the weathering crust of granite. Successive weathering of biotite, plagioclase and K-feldspar made 87Sr/86Sr ratios in the weathering residues show such a fluctuation trend as to decrease first, increase, and then decrease again till they maintain stable. This work further indicates that when Sr isotopes are used to trace biogeochemical processes on both the catchment and global scales, one must seriously take account of the prefer-ential release of Sr from dissolving solid phase and the fluctuation of 87Sr/86Sr ratios caused by the variations of relative weathering rates of Sr-contributing minerals.     

衡山花岗岩体西缘韧性剪切带的特征,成因及岩体定位机制

衡山花岗岩体由南岳岩体(早期)和白石峰岩体(晚期)组成,衡山岩体西缘形成有分带明显的韧性剪切带,向西倾斜,在XZ面上呈倾向滑动剪切运动,矿物显微变形构造显示为倾向简单剪切特征。经测定,韧性剪切带形成时温度下限为343.6℃,古差应力下限为52～62MPa,应变速率下限为2.05×10~(-14)/s-3.13×10~(-14)/s,推算总位移量在13.5km左右。在花岗岩体以外没有韧性剪切变形现象,说明该韧性剪切带是衡山岩体定位过程中由白石峰岩体沿南岳岩体边缘侵位的简单剪切作用所形成。     

湖南千里山花岗岩体的Nd-Sr同位素及岩石成因研究

本文利用Rb-Sr等时线方法测得第一阶段似斑状黑云母花岗岩、第二阶段等粒黑云母花岗岩和第三阶段花岗斑岩的成岩年龄分别为（152士9）×l0⁶ a、（137士7）×l0⁶ a ~（136士6）×10⁶ a和（131士1）×l0⁶ a。Sr-Nd同位素资料表明各阶段花岗质岩石均基本上源于地壳物质的重熔。与钨多金属矿化有关的似斑状黑云母花岗岩和等粒黑云母花岗岩属同一岩浆体系分异演化的产物，其钕模式年龄(t_DM= 2307×l0⁶ a)反映出成岩物质来自早元古宙地层的重熔。与铅，锌一银矿化有关的花岗斑岩的钕模式年龄(t_DM= 1284×l0⁶ ~ 1578×l0⁶ a)示意出其成岩物质来自中元古宙地层的重熔。     

超大型铀矿床成矿地质条件及我国北西部找矿方向分析

本文从研究国外超大型铀矿床特征和分类入手，总结其铀成矿地质条件，结合我国北西部地质特征、矿化分布特点，认为我国北西部今后寻找超大型铀矿床主要是中新生代可地浸的层间氧化带砂岩型铀矿，其次是伟晶花岗岩型、火山岩型及奥林匹克坝型（即隐爆角砾岩型）的铀矿床。     

白玉县炯隆寺-阿吉森多岩体成因分析

本文以同源岩浆演化序列的观点,探讨了炯隆寺-阿吉森多岩体的成因。研究结果表明,该岩体为印支晚期形成的同熔型花岗闪长岩-二长花岗岩,属于岛弧深成侵入的岩浆岩。     

利用尾矿废石制造微晶玻璃花岗岩的投资可行性分析

在论述尾矿废石利用现状的基础上,对利用尾矿废石制造微晶玻璃花岗岩的投资可行性进行了分析,提供了一套可用于此类决策的分析方法。     

浅议浅黄色花岗岩板材在高温条件下变色因素

奇台县菊花黄花岗岩板材,经高温氧-乙炔喷焰烧后呈褐红色薄膜状石材板,使其经济价值增加80%.菊花黄花岗岩板材中的钾长石矿物经高温氧-乙炔喷焰烧后,当其受热达到一定的温度时褐黄色微斜长石中所含的低价铁氧化物中的2价铁离子变为3价铁离子,使岩石的颜色由黄色转化为褐红色,微斜长石由三斜晶系向稳定的单斜晶系转变,由于高于900℃高温作用石材表面时间短,故能在石材表面形成厚约1mm左右的红色薄膜.经褪色强化实验,从理论上推测该红色薄膜石材在大气条件下可保持10年以上不褪色.     

Fracture in Westerly Granite under AE Feedback and Constant Strain Rate Loading: Nucleation, Quasi-static Propagation, and the Transition to Unstable Fracture Propagation

New observations of fracture nucleation are presented from three triaxial compression experiments on intact samples of Westerly granite, using Acoustic Emission (AE) monitoring. By conducting the tests under different loading conditions, the fracture process is demonstrated for quasi-static fracture (under AE Feedback load), a slowly developing unstable fracture (loaded at a `slow' constant strain rate of 2.5 × 10<sup>−6</sup> /s) and an unstable fracture that develops near instantaneously (loaded at a `fast' constant strain rate of 5 × 10⁻⁵ /s). By recording a continuous ultrasonic waveform during the critical period of fracture, the entire AE catalogue can be captured and the exact time of fracture defined. Under constant strain loading, three stages are observed: (1) An initial nucleation or stable growth phase at a rate of ~ 1.3 mm/s, (2) a sudden increase to a constant or slowly accelerating propagation speed of ~ 18 mm/s, and (3) unstable, accelerating propagation. In the ~ 100 ms before rupture, the high level of AE activity (as seen on the continuous record) prevented the location of discrete AE events. A lower bound estimate of the average propagation velocity (using the time-to-rupture and the existing fracture length) suggests values of a few m/s. However from a low gain acoustic record, we infer that in the final few ms, the fracture propagation speed increased to 175 m/s. These results demonstrate similarities between fracture nucleation in intact rock and the nucleation of dynamic instabilities in stick slip experiments. It is suggested that the ability to constrain the size of an evolving fracture provides a crucial tool in further understanding the controls on fracture nucleation.