腾冲热水沉积金矿床硅质岩特征和金银赋存状态研究

腾冲热水沉积金矿床硅质岩特征和金银赋存状态研究王江海（中国科学院广州地球化学研究所．广州５１０６４０）张丽彦（北京矿冶研究总院．北京１０００４４）关键词硅质岩，热水沉积，金赋存状态，银金矿，腾冲贵金属矿床中有用元素（如腾冲热海金矿床中的金和银）的赋存...     

综合找矿方法在山西小青沟银锰多金属矿田的应用

本文利用山西小青沟银锰多金属矿田的1：1万综合物化探测量资料,总结出激发极化法、高精度磁测、甚低频电磁法和化探原生晕是寻找该类型矿床的最佳综合找矿方法,并进行了有效的大比例尺成矿预测。     

燕山地区与变质核杂岩一伸展构造有关的金、银矿找矿远景探讨

该文在概述燕山地区前寒武系中金的背景值和近年在中、上元古界中新发现许多金、银矿床等事实的基础上,从伸展构造理论出发,研究了燕山地区金、银贵金属矿床的形成机制,认为中、上元古界中金、银贵金属矿床的形成与变质核杂岩一伸展构造密切相关,由此对燕山地区前寒武纪金、银贵金属矿远景进行了预测,并提出了进一步工作的建议。     

Variability of a cyprinid lake ecosystem with special emphasis on the native fish fauna under intensive fisheries management including common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix)

The lake investigated (Lake Heiliger See near the town of Angermünde, North-East Germany) is small (10.2 ha) but deep (z_max = 12 m, ? = 6.5 m). During summer the thermocline is at a depth of 4-5 m, and the hypolimnion is filled with H₂S already by mid-June, making 60-75% of the bottom area inaccessible to fish. The native fish fauna is dominated by planktivorous roach (Rutilus rutilus). A test stocking of silver carp (Hypophthalmichthys molitrix) together with an unplanned and erroneous stocking of common carp (Cyprinus carpio), coupled with an incorrectly calculated strong stocking of eel (Anguilla anguilla), which assumed that the total lake area yielded fish food organisms, brought about a strong depression of the food biomass available to native fish. Both silver carp and common carp showed a pattern of behaviour which only partly agreed with results obtained in experimental ponds prior to lake stocking. At least for 10 years there was a very low zooplankton biomass (mostly below 1 mg/l fresh weight) caused by silver carp and a strongly reduced benthos biomass (frequently below 1 g/m² fresh weight) caused by common carp and eel on H₂S-free bottom areas. Despite this extreme situation, which lasted for 20 years and is rarely found in lakes elsewhere, it was not possible to demonstrate negative effects on the native fish fauna comprising 16 species. Also the dominance pattern seems uninfluenced in the long run. A strong decline of the catchable roach stock was observed for some years, but the stock reappeared soon in comparable quantity. During the time of roach stock depression the individual growth of roach (and common carp) was particularly low. Nevertheless, roach succeeded in reproduction during this time in spite of the reduced zooplankton and detritus concentrations. Fry numbers per year ranged from 500-15 000 individuals/ha. The pike perch (Stizostedion lucioperca) was perhaps the most endangered species of all those living at small population numbers in the lake, since its fry is confined to the limnion where competition from silver carp and adult roach and perhaps predation by roach is highest. However the pike perch stock remained unchanged at the low level of 1950, the time prior of carp and eel stocking. All other rare species of Lake Heiliger See spawn in the littoral zone where fry survival conditions were less impacted. In summary, we present more evidence that the fish fauna of cyprinid lakes is more robust than in salmonid lakes. The regulation capacity of fish communities of eutrophic lakes seems to be able to offset even severe direct and indirect influences of fisheries management.     

刁泉银铜矿床硫化物次生富集特征

通过对刁泉银铜矿物分带性、生成顺序及硫同位素的研究，阐明了矿区次生氧化带中含铜矿物的富集规律及生成顺序，指出次生富集作用对银铜矿石的富集具有控制作用。     

锰银精矿及粗银粉中银的容量法快速测定

对某地锰银精矿及冶炼半成品——粗银粉，采用湿法溶样后，直接采用硫氰酸钾容量法测定Ag，对w(Ag)为0．22％～70．96％的样品，测定结果与原子吸收法以及火试金容量法结果相符。