Early paleozoic granodioritic plutons in the Shedong W–Mo ore district, Guangxi, southern China: Products of re-melting of middle Proterozoic crust due to magma underplating

2017 ◽  
Vol 141 ◽  
pp. 59-73 ◽  
Author(s):  
Xingzhou Jiang ◽  
Zhiqiang Kang ◽  
Jifeng Xu ◽  
Zuohai Feng ◽  
Chongjin Pang ◽  
...  
Keyword(s):  
Southern China ◽  
Early Paleozoic ◽  
Middle Proterozoic ◽  
Ore District

Age of xenocrystic zircon from diatremes of western Canada

1991 ◽  
Vol 28 (8) ◽  
pp. 1232-1238 ◽  
Author(s):  
R. R. Parrish ◽  
I. Reichenbach
Keyword(s):  
Sedimentary Cover ◽  
Crystalline Basement ◽  
Late Paleozoic ◽  
Western Canada ◽  
Magmatic Activity ◽  
Early Paleozoic ◽  
Lower Paleozoic ◽  
Single Zircon ◽  
Crustal Xenoliths ◽  
Middle Proterozoic

Numerous diatremes of middle and late Paleozoic age intrude miogeoclinal middle and lower Paleozoic strata in the Canadian Cordillera. In addition to abundant crustal xenoliths and conspicuous mantle-derived mineral xenocrysts, rare zircon grains are present. U–Pb dating of single zircon crystals from many of these diatremes has failed to identify the presence of cogenetic (magmatic) zircons. All dated zircon grains are interpreted as xenocrysts derived from the crust. Their morphologies range from euhedral to very rounded, and their ages range from early Paleozoic to Archean. Most ages fall between 1.8 and 2.1 Ga, with subordinate age groupings in the late Archean (ca. 2.6 Ga), Middle Proterozoic (1.0–1.1 Ga), and early Paleozoic (ca. 470 Ma, 530 Ma). The Proterozoic and Archean zircons could have been derived from either the crystalline basement or its overlying sedimentary cover of Late Proterozoic to early Paleozoic age. Paleozoic zircons were probably derived from either intrusions within the basement or sills that intrude the early Paleozoic sedimentary cover, and they signify magmatic activity possibly related to rifting of the continental margin.

Geological Characteristics of the Dafulou Tin–Polymetallic Sulfide Deposits in Guangxi, South China

2012 ◽  
Vol 455-456 ◽  
pp. 1350-1355
Author(s):  
Yong Sheng Cheng
Keyword(s):  
Hydrothermal Alteration ◽  
South China ◽  
Southern China ◽  
Rock Series ◽  
The West ◽  
Sulfide Deposits ◽  
Geological Characteristics ◽  
Different Types ◽  
Closed Contact ◽  
Ore District

The Danchi mineralization belt is an important ore district in southern China. According to the tectonic characteristics, the Danchi mineralization belt could be devided into three mineralization belts, such as the east mineralization belt, the west mineralization belt and the middle mineralization belt. The Dafulou deposit, which belongs to the east mineralization belt, is located in the eastern flank of the NNW–SSE-trending Danchi anticlinorium. The key structures in the Dafulou ore district are the NW-trending faults, which developed parallel with the axis of the Dachang anticlinorium. In the Dafulou ore district, the Devonian stratum has a closed contact with the Sn–polymetallic deposits. In the Danchi mineralization belt, the granite belongs to alkali-calcium rock series or near to the alkali rock series. There are four different types of hydrothermal alteration, including silicification, carbonation, pyritization and pyrrhotitezation.

Variations in Surface Textures of Quartz Sand using Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 494-495
Author(s):  
Eugene J. Amaral
Keyword(s):  
Electron Microscopy ◽  
Glass Industry ◽  
Glass Slide ◽  
Distilled Water ◽  
Early Paleozoic ◽  
Secondary Effects ◽  
Surface Textures ◽  
High Silica ◽  
Sand Deposit ◽  
The U.S

Examination of sand grain surfaces from early Paleozoic sandstones by electron microscopy reveals a variety of secondary effects caused by rock-forming processes after final deposition of the sand. Detailed studies were conducted on both coarse (≥0.71mm) and fine (=0.25mm) fractions of St. Peter Sandstone, a widespread sand deposit underlying much of the U.S. Central Interior and used in the glass industry because of its remarkably high silica purity.The very friable sandstone was disaggregated and sieved to obtain the two size fractions, and then cleaned by boiling in HCl to remove any iron impurities and rinsed in distilled water. The sand grains were then partially embedded by sprinkling them onto a glass slide coated with a thin tacky layer of latex. Direct platinum shadowed carbon replicas were made of the exposed sand grain surfaces, and were separated by dissolution of the silica in HF acid.

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