3 edition of Distribution of gold in porphyry copper deposits found in the catalog.
Distribution of gold in porphyry copper deposits
1988 by U.S. Dept. of the Interior, U.S. Geological Survey in [Reston, Va.?] .
Written in English
|Statement||by Dennis P. Cox and Donald A. Singer|
|Series||U.S. Geological Survey open-file report -- 88-46|
|Contributions||Singer, D. A, Geological Survey (U.S.)|
|The Physical Object|
So this gives us a start in deciding where to focus our exploration because of the extensive subduction during the tertiary i. You will also remember that nature concentrates the metals by a process of partially melting the crustal rocks at depth and letting them rise through the crust and cool and then dumping the value less minerals such as feldspars and quartz and concentrating the metals in the remaining magma and hydrothermal fluids. Porphyry copper deposits and their close relatives, porphyry molybdenum deposits contain disseminated mineralization, meaning that a large volume of shattered rock contains a ramifying network of tiny quartz veins, spaced only a few centimetres apart, in which grains of the copper ore minerals chalcopyrite and bornite or the molybdenum ore mineral molybdenite occur with pyrite. Erich U. They range from 0.
Brines, and especially sodium-calcium chloride brines, are effective solvents of many sulfide and oxide ore minerals, and they are even capable of dissolving and transporting native metals such as gold and silver. Porphyry copper deposits commonly contain hundreds of millions of metric tons of ore that averages a fraction of 1 percent copper by weight; although they are low-grade, the deposits constitute important sources because they may be worked on a large scale at low cost. Reserves of 37, tons at 2. Load Next Page. Skarns are often striking looking rocks containing red garnets and green pyroxenes. In the second and final stage, the magma is cooled rapidly at relatively shallow depth or as it erupts from a volcanocreating small grains that are usually invisible to the unaided eye.
The West Zone outcrops, while the East Zone, which extends to a depth of at least m, is unconformably overlain by a sequence of Late Cretaceous to Eocene sedimentary and volcanic rocks. These alteration types become important in the exploration of porphyry style mineralization as they provide vectors to the mineralization. Leucocratic Quartz Diorite is a later intrusive phase which occurs on the southern margin of the main intrusive mass. The driver probably barely noticed when he drove over this SUV everything about porphyry deposits is big. Early pyrite in the Kawerong Quartz Diorite, ii.
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Of the latter, most still exist in complete or fragmentary form, despite depredations by later Byzantine Emperors, Crusadersand Ottoman conquerors.
As with almost all ore deposit types porphyry targets need to be drilled eventually to quantitatively determine actual copper, gold and molybdenum values in the identified mineralization.
Examples of porphyry copper deposits[ edit ]. You could not be signed in. Idealized drawing of a porphyry copper deposit, showing the relationship between the porphyry body, the altered and mineralized rock, and the overlying volcano.
Collectively, these type of deposits are known as " porphyry copper deposits ". View Larger Image So how do we explore for Porphyry Copper Deposits which are completely covered by barren younger rocks?
Leucocratic Quartz Diorite is a later intrusive phase which occurs on the southern margin of the main intrusive mass.
The hydrothermal solutions may also deposit ore minerals of iron, copper, zinc, tungsten, or molybdenum. References Fitzmayer, J. Eppinger, David L.
Continuing active volcanism at the Bagana Volcano, 32 km north of the mine, has resulted in a blanket of recent ash to several metres thick obscuring much of the island, including the Panguna area.
Distribution of gold in porphyry copper deposits book sediments, geochemistry is a cheap method of first pass evaluation. The northern section of the Kahiltna terrane is dominated by Late Triassic basalt, andesite and sedimentary rocks which are overlain by Jurassic to Cretaceous andesitic turbidites, which were intruded by intermediate to felsic Cretaceous plutons, and capped by Tertiary volcanic and sedimentary units and by Quaternary glacial deposits.
The main lithologies of the mineralised complex in the mine area Fig. Theme Session on Transition between porphyry copper and epithermal systems. The most recent source geological information used to prepare this summary was dated: She notes that these Sicilian porphyry sarcophagi "are the very first examples of medieval free-standing secular tombs in the West, and therefore play a unique role within the history of Italian sepulchral art earlier and later tombs are adjacent to, and dependent on walls.
The water in a hydrothermal solution can come from any of several sources. If the cover rocks are thicker than that or weathering has oxidized the sulfides to deeper than this, IP is of little use. If gold is present in the ore-forming solutions, more of it will be deposited in high-temperature porphyry copper-gold deposits where it will be closely associated with bornite.
Kawerong Quartz Diorite - the bulk of the intrusion is un-mineralised and occurs to the north-west of the Panguna mine.
Electrum exhibits significant compositional differences between Stage I and II. VMS deposits constitute some of the richest deposits of copper, lead, and zinc known.
HoschAssociate Editor. Intense quartz veining with chalcopyrite and bornite accompanied the subsequently intruded Leucocratic Quartz Diorite to form a stronger zone of Cu-Au mineralisation in the south of the ore zone annulus, iv.
In addition, mineralisation amenable to upgrading by screening would add a further Mt Distribution of gold in porphyry copper deposits book. I would like to thank Jeff for his generous support in making this presentation possible and Battle Mountain Gold for their generous support for our studies in the Kori Kollo District.
The intrusives also simulates the limestone altering its composition and forming and endo skarns.For copper-molybdenum porphyry deposits, formation is broadly concentrated in three time periods: Palaeocene-Eocene, Eocene-Oligocene, and middle Miocene-Pliocene.
For both porphyry and epithermal gold deposits, they are generally from the time period ranging from the middle Miocene to the Recent period., however notable exceptions are known.
Porphyry copper deposit, large body of rock, typically a porphyry of granitic to dioritic composition, that has been fractured on a fine scale and through which chalcopyrite and other copper minerals are disseminated. Porphyry copper deposits commonly contain hundreds of millions of metric tons of.
This report contains a revised descriptive model of porphyry copper deposits (PCDs), the world's largest source (about 60 percent) and resource (about 65 percent) of copper and a major source of molybdenum, gold and silver.
Despite relatively low grades (average percent copper in ), PCDs have significant economic and societal impacts due to their large size (commonly hundreds of.The Panguna porphyry copper-gold deposit is located in the Crown Prince Pdf of central-south Bougainville Island in eastern Pdf New Guinea, at an altitude of to m (#Location: 6° 19' 0"S, ° 29' 36"E).
Gold was initially discovered by prospectors at Kupei inand shortly after at nearby Panguna, some km to the sout-west.Mar 23, · Eleven gold‐rich porphyry copper and 14 epithermal gold deposits around the Pacific rim contain > t (‐7 million oz) of gold.
These large porphyry‐type deposits conform to a single overall model, whereas the large epithermal gold deposits are varied in Cited by: Note: Citations are based on reference standards.
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