Chemical composition of Archaean hydrothermal fluids from the Dresser formation (Pilbara Drilling Project, Australia)

2006 ◽  
Vol 70 (18) ◽  
pp. A507
Author(s):  
M. Pujol ◽  
P. Philippot ◽  
B. Marty
Keyword(s):  
Chemical Composition ◽  
Hydrothermal Fluids ◽  
Drilling Project

scholarly journals Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides

2015 ◽  
Vol 68 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Gisele Tavares Marques ◽  
Marcondes Lima da Costa ◽  
Érico Rodrigues Gomes
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
High Stability ◽  
Hydrothermal Fluids ◽  
Northeastern Brazil ◽  
Quartz Crystals ◽  
Hydrothermal Processes ◽  
Hydrothermal Environment

Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins.

scholarly journals A study on Chinese ancient jades with mercury alteration unearthed from Lizhou’ao Tomb

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yi Bao ◽  
Changqing Xu ◽  
Qinwen Zhu ◽  
Yuesheng Li
Keyword(s):  
Chemical Composition ◽  
Surface Water ◽  
Human Activity ◽  
Environmental Conditions ◽  
Structural Changes ◽  
Hydrothermal Fluids ◽  
Jiangxi Province ◽  
High Grade ◽  
Structural Hierarchy ◽  
Spring And Autumn Period

Abstract“Alteration” geologically refers to chemical composition and/or structural changes of minerals under the influences of hydrothermal fluids, surface water, seawater, or other environmental conditions. In this paper, we use the word “alteration” to refer to chemical component and structural changes in jade artifacts caused by human activity and natural weathering, which is different from the term in geology. “Mercury alteration”, a kind of black alteration related to Hg, is unique among the several types of alteration that occur in Chinese ancient jades. Mercury alteration often appears on ancient jade artifacts unearthed from high-grade tombs of the pre-Qin period (before 221 B.C.). Therefore, ancient jades with mercury alteration have attracted substantial attention from Chinese archaeologists. This paper reports the use of materials analytic techniques to study such ancient jade fragments. The studied jade samples date to the middle and late periods of the Spring and Autumn Period (~500 B.C.) and were unearthed from Lizhou’ao Tomb in Jiangxi Province, China. Structural analyses revealed the internal microstructure of the ancient jade fragments and the microdistribution of the mercury alteration. The jade fragments exhibit typical characteristics of round holes and structural hierarchy, which imply that the jades were heated before burial. The black alteration on these jade samples was found to be rich in Hg. The results of this study will be widely useful in the study of ancient jade artifacts and jade culture in Chinese archeology.

scholarly journals Scientific Results of Conduit Drilling in the Unzen Scientific Drilling Project (USDP)

2005 ◽  
Vol 1 ◽  
pp. 18-22 ◽  
Author(s):  
S. Nakada ◽  
K. Uto ◽  
S. Sakuma ◽  
J. C. Eichelberger ◽  
H. Shimizu
Keyword(s):  
Lava Dome ◽  
Hydrothermal Fluids ◽  
Seismic Signals ◽  
Directional Drilling ◽  
Geological Investigation ◽  
Unzen Volcano ◽  
Scientific Drilling ◽  
Core Samples ◽  
Scientific Results ◽  
Drilling Project

Directional drilling at Unzen Volcano in Japan during mid of 2004 penetrated the magma conduit and successfully recovered samples of the lava dike that is believed to have fed the 1991–1995 eruption. The dike was sampled about 1.3 km below the volcano’s summit vent and is intruded into a broader conduit zone that is 0.5 km wide. This zone consists of multiple older lava dikes and pyroclastic veins and has cooled to less than 200 ˚C. The lava dike sample was unexpectedly altered, suggesting that circulation of hydrothermal fluids rapidly cools the conduit region of even very active volcanoes. It is likely that seismic signals monitored prior to emergence of the lava dome reflected fracturing of the country rocks, caused by veining as volatiles escaped predominantly upward, not outward, from the rising magma. Geophysical and geological investigation of cuttings and core samples from the conduit and of bore-hole logging data continues. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.3.01.2006" target="_blank">10.2204/iodp.sd.3.01.2006</a>

Chemical composition of hydrothermal fluids in the central and southern Mariana Trough backarc basin

2015 ◽  
Vol 121 ◽  
pp. 126-136 ◽  
Author(s):  
Jun-ichiro Ishibashi ◽  
Urumu Tsunogai ◽  
Tomohiro Toki ◽  
Naoya Ebina ◽  
Toshitaka Gamo ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Hydrothermal Fluids ◽  
Backarc Basin
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