Gold concentrations of magmatic brines and the metal budget of porphyry copper deposits
Article Abstract:
The Au/Cu ratio of primary high-temperature brines is identical to the bulk Au/Cu ratio in the Grasberg porphyry copper-gold deposit in Irian Jaya, Indonesia, and the Bajo de la Alumbrera gold-rich copper deposit in Argentina. Co-precipitation of Cu and Au was very efficient in both deposits, but metal precipitation was also extremely selective. It appears that very large volumes of ore metals are flushed through ore deposits. These are eventually dispersed if steep thermal and chemical gradients do not provide a driving force for efficient mineral precipitation.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Nature of the heating mechanism for the diffuse solar corona
Article Abstract:
The nature of the coronal heating mechanism remains a mystery. The corona comprises of several plasma structures including coronal loops which are magnetic and occur over a range of scales. X-ray observations of the diffuse corona show that variations in temperature along a loop is sensitive to the spatial distribution of the heating. It is concluded that the best fit to the loop temperature distribution is uniform heating, eliminating previously suggested mechanisms.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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Forest-killing diffuse CO2 emission at Mammoth Mountain as a sign of magmatic unrest
Article Abstract:
The results of a 1994-95 soil-gas survey in Mammoth Mountain, CA, identified CO2 concentrations of 30-96% in a 30-hectare region of killed trees. A total CO2 flux of at least 1,200 tons per day was estimated. The magnitude and duration of the CO2 flux suggest the existence of a large, deep magma source or a large reservoir of high-pressure gas.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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