Misplaced Pages

#474525

119-519: After a long shutdown, the Climax mine reopened and resumed molybdenum shipment on May 10, 2012. The mine is owned by Climax Molybdenum Company, a subsidiary of Freeport-McMoRan . The prospector Charles Senter discovered and claimed the outcropping of molybdenite (molybdenum sulfide) veins in 1879, during the Leadville , Colorado Silver Boom , but had no idea what the mineral there was. Senter determined that

238-473: A proxy fight for control of the company. In 1929, he then sought help from his former supervisor at Lee, Higginson & Co. , J.T. Claiborne, who then enlisted clerk John Hay Whitney – who had become one of the wealthiest men in America following the 1927 death of his father, Payne Whitney . Williams eventually gained control of the company from founder Swenson, becoming its president in 1931, with Claiborne as

357-500: A reflexive verb . The lower plate itself is the subject. It subducts, in the sense of retreat, or removes itself, and while doing so, is the "subducting plate". Moreover, the word slab is specifically attached to the "subducting plate", even though in English the upper plate is just as much of a slab. The upper plate is left hanging, so to speak. To express it geology must switch to a different verb, typically to override . The upper plate,

476-563: A stockwork in an altered quartz monzonite porphyry . Like other porphyry-type ore deposits, the ore is low-grade, much less than one percent molybdenum, but the ore bodies are very large. Beside molybdenum, the mine has also produced tin (from cassiterite ), tungsten (from hübnerite ), and pyrite as by-products. The rocks of the Climax Stock are alkaline felsic intrusives. They range from porphyritic alkaline rhyolite to alkaline aplite to porphyritic alkaline granite. In map view,

595-521: A 1996 Dames & Moore environmental audit. The report, endorsed by Freeport, also estimated that during the life of the mine 3.2 billion tons of waste rock – large components of which generate acid  – would be dumped into the local river system. Overburden (waste rock) from the mine had already polluted a nearby lake due to acid mine drainage . Citing extensive, long-term and irreversible environmental damage in New Guinea,

714-457: A 2,000-foot (610 m) cliff separates the Ertsberg mine (at 12,000 feet (3,700 m) elevation) from the mill (at 10,000 feet). Moving copper concentrate from that mill to the shipping port required installation of a 109-kilometre (68 mi) slurry pipeline – then the world's longest. Mine construction and startup cost about US$ 200 million. The Ertsberg project was an engineering marvel, but

833-578: A 25% interest in oil and gas assets primarily in the western United States to Britoil for $ 73.5 million. In 1989, the company sold about $ 1.5 billion in assets to finance development of the Grasberg mine and the Main Pass offshore sulfur-oil-gas deposit off Louisiana. In 1994, the company completed the corporate spin-off of its entire interest in Freeport-McMoRan Copper & Gold, which owned

952-530: A Vice-President, and Whitney as Chairman. Williams also served as Chairman during 1958–1967. Williams led the company's diversification, beginning with the purchase of manganese deposits in Oriente Province , Cuba. In 1932, Freeport Sulphur Company acquired the sulfur rights for Lake Grande Ecaille and vicinity in Plaquemines Parish , Louisiana, and escalated the development of sulfur deposits in

1071-408: A chemist who identified the gray mineral as containing molybdenum in 1895, at the time there was virtually no market for the metal. When steelmakers determined the utility of molybdenum as an alloy in producing hard steel, the first ore shipments from the deposit began in 1915, and the Climax mine began full production in 1914. The main ore-bearing area was Bartlett Mountain, which was mined out during

1190-406: A consequence of the rigidity of the plate. The point where the slab begins to plunge downwards is marked by an oceanic trench . Oceanic trenches are the deepest parts of the ocean floor. Beyond the trench is the forearc portion of the overriding plate. Depending on sedimentation rates, the forearc may include an accretionary wedge of sediments scraped off the subducting slab and accreted to

1309-400: A landslide killed eight workers. A government study concluded that the incident was the result of negligence. Important warning signs had been detected two days prior. In response to this, management moved some equipment, but did not keep workers out of the area. A month later two workers died from being exposed to sulfur fumes. The government ultimately overturned its conclusion and attributed

SECTION 10

#1732855778475

1428-460: A larger portion of Earth's crust to deform in a more brittle fashion than it would in a normal geothermal gradient setting. Because earthquakes can occur only when a rock is deforming in a brittle fashion, subduction zones can cause large earthquakes. If such a quake causes rapid deformation of the sea floor, there is potential for tsunamis . The largest tsunami ever recorded happened due to a mega-thrust earthquake on December 26, 2004 . The earthquake

1547-457: A minimum estimate of how far the continent has subducted. The results show at least a minimum of 229 kilometers of subduction of the northern Australian continental plate. Another example may be the continued northward motion of India, which is subducting beneath Asia. The collision between the two continents initiated around 50 my ago, but is still active. Oceanic-Oceanic plate subduction zones comprise roughly 40% of all subduction zone margins on

1666-460: A point of no return. Sections of crustal or intraoceanic arc crust greater than 15 km (9.3 mi) in thickness or oceanic plateau greater than 30 km (19 mi) in thickness can disrupt subduction. However, island arcs subducted end-on may cause only local disruption, while an arc arriving parallel to the zone can shut it down. This has happened with the Ontong Java Plateau and

1785-898: A sale to China Molybdenum of Tenke Fungurume Mine , a cobalt/ copper mine in DRC Congo, were not successful. Instead, the Kisanfu mine was sold to China Molybdenum in a separate transaction in 2020. In December 2019, Freeport Cobalt (a joint venture between Freeport-McMoRan and Lundin Mining ) sold its cobalt refinery in Kokkola , Finland to Umicore . FCX held an effective 56% interest in that enterprise. Arizona Colorado New Mexico Past board members include Henry Kissinger , John Hay Whitney , Robert A. Lovett , Benno C. Schmidt Sr. , Gus Long , Arleigh Burke , J. Stapleton Roy , Godfrey Rockefeller and his cousin-in-law, Jean Mauzé . In 2011, Freeport

1904-471: A series of minerals in these slabs such as serpentine can be stable at different pressures within the slab geotherms, and may transport significant amount of water into the Earth's interior. As plates sink and heat up, released fluids can trigger seismicity and induce melting within the subducted plate and in the overlying mantle wedge. This type of melting selectively concentrates volatiles and transports them into

2023-521: A smelter in exchange for a special permit to operate the mine until 2041. In 2018, the company ranked at number 176 on the Fortune 500 list. During this year, Indonesian President Joko Widodo also planned to take control of 51% of Freeport Indonesia's equity, effectively handing over Freeport control to the Indonesian government. The Indonesian government planned to settle payments of $ 3.85 billion during

2142-411: A steeper angle is characterized by the formation of back-arc basins . According to the theory of plate tectonics , the Earth's lithosphere , its rigid outer shell, is broken into sixteen larger tectonic plates and several smaller plates. These plates are in slow motion, due mostly to the pull force of subducting lithosphere. Sinking lithosphere at subduction zones are a part of convection cells in

2261-426: A total enterprise value of over $ 20 billion. The transaction added significantly to the company's petroleum assets. The transaction was criticized as a conflict of interest due to the common ownership of the companies. In 2015, the company paid a $ 137.5 million settlement to resolve claims that executives and directors had conflicts of interest that resulted in the company overpaying in that transaction. In 2014,

2380-510: A zone of shortening and crustal thickening in which there may be extensive folding and thrust faulting . If the angle of subduction steepens or rolls back, the upper plate lithosphere will be put in tension instead, often producing a back-arc basin . The arc-trench complex is the surface expression of a much deeper structure. Though not directly accessible, the deeper portions can be studied using geophysics and geochemistry . Subduction zones are defined by an inclined zone of earthquakes ,

2499-418: Is "consumed", which happens the geological moment the lower plate slips under, even though it may persist for some time until its remelting and dissipation. In this conceptual model, plate is continually being used up. The identity of the subject, the consumer, or agent of consumption, is left unstated. Some sources accept this subject-object construct. Geology makes to subduct into an intransitive verb and

SECTION 20

#1732855778475

2618-456: Is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle. A region where this process occurs is known as a subduction zone , and its surface expression

2737-499: Is accreted to (scraped off) the continent, resulting in exotic terranes . The collision of this oceanic material causes crustal thickening and mountain-building. The accreted material is often referred to as an accretionary wedge or prism. These accretionary wedges can be associated with ophiolites (uplifted ocean crust consisting of sediments, pillow basalts, sheeted dykes, gabbro, and peridotite). Subduction may also cause orogeny without bringing in oceanic material that accretes to

2856-488: Is characterized by low geothermal gradients and the associated formation of high-pressure low-temperature rocks such as eclogite and blueschist . Likewise, rock assemblages called ophiolites , associated with modern-style subduction, also indicate such conditions. Eclogite xenoliths found in the North China Craton provide evidence that modern-style subduction occurred at least as early as 1.8  Ga ago in

2975-493: Is driven mostly by the negative buoyancy of the dense subducting lithosphere. The down-going slab sinks into the mantle largely under its own weight. Earthquakes are common along subduction zones, and fluids released by the subducting plate trigger volcanism in the overriding plate. If the subducting plate sinks at a shallow angle, the overriding plate develops a belt of deformation characterized by crustal thickening, mountain building , and metamorphism . Subduction at

3094-444: Is fairly well understood, the process by which subduction is initiated remains a matter of discussion and continuing study. Subduction can begin spontaneously if the denser oceanic lithosphere can founder and sink beneath the adjacent oceanic or continental lithosphere through vertical forcing only; alternatively, existing plate motions can induce new subduction zones by horizontally forcing the oceanic lithosphere to rupture and sink into

3213-593: Is found behind the Aleutian Trench subduction zone in Alaska. Volcanoes that occur above subduction zones, such as Mount St. Helens , Mount Etna , and Mount Fuji , lie approximately one hundred kilometers from the trench in arcuate chains called volcanic arcs . Plutons, like Half Dome in Yosemite National Park, generally form 10–50 km below the volcanoes within the volcanic arcs and are only visible on

3332-447: Is known as an arc-trench complex . The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. Subduction is possible because the cold and rigid oceanic lithosphere is slightly denser than the underlying asthenosphere , the hot, ductile layer in the upper mantle . Once initiated, stable subduction

3451-477: Is more buoyant and as a result will rise into the lithosphere, where it forms large magma chambers called diapirs. Some of the magma will make it to the surface of the crust where it will form volcanoes and, if eruptive on earth's surface, will produce andesitic lava. Magma that remains in the lithosphere long enough will cool and form plutonic rocks such as diorite, granodiorite, and sometimes granite. The arc magmatism occurs one hundred to two hundred kilometers from

3570-411: Is old, goes down the subduction zone. As this happens, metamorphic reactions increase the density of the continental crustal rocks, which leads to less buoyancy. One study of the active Banda arc-continent collision claims that by unstacking the layers of rock that once covered the continental basement, but are now thrust over one another in the orogenic wedge, and measuring how long they are, can provide

3689-571: Is on Fremont Pass , along the Continental Divide. About 20 different federal or state agencies affected Climax operations, including the U.S. EPA , the U.S. Forest Service , and the Bureau of Land Management . In 1991, the mine declared the Storke Level ore abandoned; no more ore could be extracted profitably, so the company redirected its focus to other activities, such as open-pit reclamation,

Climax mine - Misplaced Pages Continue

3808-551: Is one of a number of large molybdenum deposits in central Colorado and northern New Mexico. Other molybdenum deposits in the region include the Questa mine in New Mexico, and the Henderson and Urad mines near Empire, Colorado . Historically, mining was principally by "sub-level induced panel caving", a method that removes ore by undercutting the base of a panel in the ore deposit, causing

3927-689: Is ongoing beneath part of the Andes , causing segmentation of the Andean Volcanic Belt into four zones. The flat-slab subduction in northern Peru and the Norte Chico region of Chile is believed to be the result of the subduction of two buoyant aseismic ridges, the Nazca Ridge and the Juan Fernández Ridge , respectively. Around Taitao Peninsula flat-slab subduction is attributed to the subduction of

4046-519: The Cascade Volcanic Arc , that form along the coast of continents. Island arcs (intraoceanic or primitive arcs) are produced by the subduction of oceanic lithosphere beneath another oceanic lithosphere (ocean-ocean subduction) while continental arcs (Andean arcs) form during the subduction of oceanic lithosphere beneath a continental lithosphere (ocean-continent subduction). An example of a volcanic arc having both island and continental arc sections

4165-754: The Chile Rise , a spreading ridge . The Laramide Orogeny in the Rocky Mountains of the United States is attributed to flat-slab subduction. During this orogeny, a broad volcanic gap appeared at the southwestern margin of North America, and deformation occurred much farther inland; it was during this time that the basement -cored mountain ranges of Colorado, Utah, Wyoming, South Dakota, and New Mexico came into being. The most massive subduction zone earthquakes, so-called "megaquakes", have been found to occur in flat-slab subduction zones. Although stable subduction

4284-567: The Government Pension Fund of Norway excluded Freeport-McMoRan from its investment portfolio, following a recommendation from the fund's ethical council. In 2013, a tunnel collapse killed twenty eight workers. The Freeport geological team claimed that the collapse at the Big Gossan tunnel was caused by erosion of the ceiling, brought about by the continuous infiltration of the limestone wallrocks by corrosive acidic groundwater. Freeport

4403-624: The Jayawijaya Mountains in what was then called the Netherlands New Guinea . In 1967, the company negotiated a contract with the Indonesian government to develop the Ertsberg deposit. In their feasibility study , Freeport geologists estimated that the orebody totaled 33 million tons averaging 2.5% copper, making it the largest above-ground copper deposit ever discovered. Construction of an open pit mine began in May 1970 and in mid-1973

4522-621: The Paleoproterozoic Era . The eclogite itself was produced by oceanic subduction during the assembly of supercontinents at about 1.9–2.0 Ga. Blueschist is a rock typical for present-day subduction settings. The absence of blueschist older than Neoproterozoic reflects more magnesium-rich compositions of Earth's oceanic crust during that period. These more magnesium-rich rocks metamorphose into greenschist at conditions when modern oceanic crust rocks metamorphose into blueschist. The ancient magnesium-rich rocks mean that Earth's mantle

4641-484: The Vitiaz Trench . Subduction zones host a unique variety of rock types created by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. The metamorphic conditions the slab passes through in this process create and destroy water bearing (hydrous) mineral phases, releasing water into the mantle. This water lowers the melting point of mantle rock, initiating melting. Understanding

4760-533: The Wadati–Benioff zone , that dips away from the trench and extends down below the volcanic arc to the 660-kilometer discontinuity . Subduction zone earthquakes occur at greater depths (up to 600 km (370 mi)) than elsewhere on Earth (typically less than 20 km (12 mi) depth); such deep earthquakes may be driven by deep phase transformations , thermal runaway , or dehydration embrittlement . Seismic tomography shows that some slabs can penetrate

4879-406: The core–mantle boundary . Here the slabs are heated up by the ambient heat and are not detected anymore ~300 Myr after subduction. Orogeny is the process of mountain building. Subducting plates can lead to orogeny by bringing oceanic islands, oceanic plateaus, sediments and passive continental margins to convergent margins. The material often does not subduct with the rest of the plate but instead

Climax mine - Misplaced Pages Continue

4998-411: The lower mantle and sink clear to the core–mantle boundary . Here the residue of the slabs may eventually heat enough to rise back to the surface as mantle plumes . Subduction typically occurs at a moderately steep angle by the time it is beneath the volcanic arc. However, anomalous shallower angles of subduction are known to exist as well as some that are extremely steep. Flat-slab subduction

5117-416: The zeolite , prehnite-pumpellyite, blueschist , and eclogite facies stability zones of subducted oceanic crust. Zeolite and prehnite-pumpellyite facies assemblages may or may not be present, thus the onset of metamorphism may only be marked by blueschist facies conditions. Subducting slabs are composed of basaltic crust topped with pelagic sediments ; however, the pelagic sediments may be accreted onto

5236-501: The Alaskan crust. The concept of subduction would play a role in the development of the plate tectonics theory. First geologic attestations of the "subduct" words date to 1970, In ordinary English to subduct , or to subduce (from Latin subducere , "to lead away") are transitive verbs requiring a subject to perform an action on an object not itself, here the lower plate, which has then been subducted ("removed"). The geological term

5355-584: The Alps. The chemistry of the inclusions supports the existence of a carbon-rich fluid in that environment, and additional chemical measurements of lower pressure and temperature facies in the same tectonic complex support a model for carbon dissolution (rather than decarbonation) as a means of carbon transport. Elastic strain caused by plate convergence in subduction zones produces at least three types of earthquakes. These are deep earthquakes, megathrust earthquakes, and outer rise earthquakes. Deep earthquakes happen within

5474-533: The April 5th annual stockholders' meeting, claiming, according to reports, that "management has refused them adequate information regarding the property. President E.P. Swenson denies that information has been thus withheld and states that the board, which represents the dominant interests, has no vacancies at the present time." In 1928, shareholder and scion of one of the founding investment firms, John Langbourne Williams & Sons, Langbourne Meade Williams, Jr. launched

5593-569: The Canadian mining company Bre-X 's claims of having found the largest gold mine ever discovered, in Borneo. Freeport announced that its prospective partner Bre-X did not have gold reserves at its Indonesian mine, as it had reported. Bre-X subsequently was exposed as a fraud and went bankrupt. In 1998, low commodity prices forced the company to suspend its dividend. In 2003, the company was subpoenaed as part of an investigation by anti-trust authorities in

5712-713: The Grand Ecaille dome in 1933, still using the Frasch Process developed by Dr. Herman Frasch , who had, in 1895, enjoined the American Sulphur Company into a partnership, forming the Union Sulphur Company , to initiate the first successful sulfur mining at Grand Ecaille, with which Freeport, like other competitors, would compete upon expiry of the Frasch patents in 1908. From its earliest inception, sulfur mining

5831-507: The Grasberg mine. In 1995, RTZ, a predecessor of Rio Tinto Group , made a $ 450 million investment in the company. In 1997, IMC Global , a large fertilizer producer, acquired Freeport-McMoRan Inc., the former parent company that now owned the sulfur and fertilizer businesses, in a $ 750 million transaction. Shareholders of Freeport-McMoRan received shares of IMC Global. In 1997, the Indonesian government asked Freeport-McMoRan to substantiate

5950-481: The United States, Canada, and Europe into price fixing in the copper industry. On March 19, 2007, the company acquired Phelps Dodge (for $ 25.9 Billion) and became the largest copper producer of any public company in the world. The corporate headquarters was moved from New Orleans , Louisiana to Phoenix, Arizona . In 2012, the company announced agreements to acquire affiliated companies McMoRan Exploration Company and Plains Exploration & Production Company for

6069-595: The adjacent stream drainage to the north. Most of the liquid is drained and the remaining solid pulverized minerals and waste are called tailings . When full—as seen from the highway—these tailings reservoirs look quite striking; something like a cross between a reservoir and a dammed mountain meadow. The Climax tailing impoundment now covers several square miles. The Climax mine is located at 39°21′57″N 106°11′09″W  /  39.36583°N 106.18583°W  / 39.36583; -106.18583 (39.365890,-106.185780) at an elevation of about 11,360 feet (3,460 meters). It

SECTION 50

#1732855778475

6188-514: The army realized that the Germans were using molybdenum as an alloy to strengthen and increase the durability of their tanks and other weapons. The Climax Molybdenum Company re-opened the mine in 1924, and operated it nearly continuously until the 1980s. The mine was shut down between 1995 and 2012 due to low molybdenum prices. The mine's owner, Freeport-McMoRan Copper & Gold, continued to work on environmental cleanup of past operations while holding

6307-472: The asthenosphere. Both models can eventually yield self-sustaining subduction zones, as the oceanic crust is metamorphosed at great depth and becomes denser than the surrounding mantle rocks. The compilation of subduction zone initiation events back to 100 Ma suggests horizontally-forced subduction zone initiation for most modern subduction zones, which is supported by results from numerical models and geologic studies. Some analogue modeling shows, however,

6426-523: The colder oceanic lithosphere is, on average, more dense. Sediments and some trapped water are carried downwards by the slab and recycled into the deep mantle. Earth is so far the only planet where subduction is known to occur, and subduction zones are its most important tectonic feature. Subduction is the driving force behind plate tectonics , and without it, plate tectonics could not occur. Oceanic subduction zones are located along 55,000 km (34,000 mi) convergent plate margins, almost equal to

6545-574: The company changed its name to Freeport Minerals Company, (not to be confused with Freeport Minerals Corporation, founded in 1834). In 1981, Freeport Minerals Company merged with the McMoRan Oil and Gas Company. In 1981, the company formed a 70/30 joint venture with an affiliate of FMC Corporation to operate the Jerritt Canyon gold mine near Elko, Nevada . In 1985, the company headquarters moved to New Orleans , Louisiana . The company also sold

6664-577: The company for annual fees of $ 1.5 million. In May 2016, the company sold a 13% interest in its Morenci Mine to Sumitomo Group for $ 1 billion in cash. In 2016, Freeport sold its deepwater assets, including the Marlin TLP, and the Holstein and Horn Mountain spars, to Anadarko Petroleum . In August 2017, the company agreed to give a 51% interest in the Grasberg mine to the Government of Indonesia and build

6783-417: The company had spent about US$ 200 million preparing for a restart of the mine, with an estimated US$ 350 million more needed to complete the capital improvements and reopen. In May 2012, following a 17-year shutdown, the Climax mine reopened and resumed shipment of molybdenum. The ore deposit is a porphyry type, similar to many large copper deposits, where many intersecting small veins of molybdenite form

6902-589: The company sold its assets in the Eagle Ford shale to Encana for $ 3.1 billion. In 2015, the company announced job cuts at its Sierrita Mine in Arizona due to low copper and molybdenum prices. On December 28, 2015, the company announced that James R. Moffett would resign as chairman of the company and be replaced by Gerald J. Ford . Moffett received $ 16.1 million in severance pay and cash retirement plans totaling more than $ 63 million. Moffett continued to consult for

7021-517: The company. In 1956, the company formed the Freeport Oil Company. In 1958, the company sold an oil discovery near Lake Washington in Louisiana for approximately $ 100 million to Magnolia Petroleum Company . In 1959, Freeport geologists confirmed the 1936 Dutch discovery of the rich Ertsberg copper and gold deposits, now known as the Grasberg mine , in extremely rugged, remote country in

7140-435: The continent, away from the trench, and has been described in western North America (i.e. Laramide orogeny, and currently in Alaska, South America, and East Asia. The processes described above allow subduction to continue while mountain building happens concurrently, which is in contrast to continent-continent collision orogeny, which often leads to the termination of subduction. Continents are pulled into subduction zones by

7259-564: The crust would be melted and recycled into the Earth's mantle . In 1964, George Plafker researched the Good Friday earthquake in Alaska . He concluded that the cause of the earthquake was a megathrust reaction in the Aleutian Trench , a result of the Alaskan continental crust overlapping the Pacific oceanic crust. This meant that the Pacific crust was being forced downward, or subducted , beneath

SECTION 60

#1732855778475

7378-597: The crust, megathrust earthquakes on the subduction interface near the trench, and outer rise earthquakes on the subducting lower plate as it bends near the trench. Anomalously deep events are a characteristic of subduction zones, which produce the deepest quakes on the planet. Earthquakes are generally restricted to the shallow, brittle parts of the crust, generally at depths of less than twenty kilometers. However, in subduction zones quakes occur at depths as great as 700 km (430 mi). These quakes define inclined zones of seismicity known as Wadati–Benioff zones which trace

7497-609: The crust, through hotspot magmatism or extensional rifting, would the crust be able to break from its continent and begin subduction. Subduction can continue as long as the oceanic lithosphere moves into the subduction zone. However, the arrival of buoyant continental lithosphere at a subduction zone can result in increased coupling at the trench and cause plate boundary reorganization. The arrival of continental crust results in continental collision or terrane accretion that may disrupt subduction. Continental crust can subduct to depths of 250 km (160 mi) where it can reach

7616-408: The cumulative plate formation rate 60,000 km (37,000 mi) of mid-ocean ridges. Sea water seeps into oceanic lithosphere through fractures and pores, and reacts with minerals in the crust and mantle to form hydrous minerals (such as serpentine) that store water in their crystal structures. Water is transported into the deep mantle via hydrous minerals in subducting slabs. During subduction,

7735-448: The degree of lower plate curvature of the subducting plate in great historical earthquakes such as the 2004 Sumatra-Andaman and the 2011 Tōhoku earthquake, it was determined that the magnitude of earthquakes in subduction zones is inversely proportional to the angle of subduction near the trench, meaning that "the flatter the contact between the two plates, the more likely it is that mega-earthquakes will occur". Outer rise earthquakes on

7854-440: The descending slab. Nine of the ten largest earthquakes of the last 100 years were subduction zone megathrust earthquakes. These included the 1960 Great Chilean earthquake which at M 9.5 was the largest earthquake ever recorded, the 2004 Indian Ocean earthquake and tsunami , and the 2011 Tōhoku earthquake and tsunami . The subduction of cold oceanic lithosphere into the mantle depresses the local geothermal gradient and causes

7973-455: The different regimes present in this setting. The models are as follows: In their 2019 study, Macdonald et al. proposed that arc-continent collision zones and the subsequent obduction of oceanic lithosphere was at least partially responsible for controlling global climate. Their model relies on arc-continent collision in tropical zones, where exposed ophiolites composed mainly of mafic material increase "global weatherability" and result in

8092-551: The early mining. The demand for molybdenum fell drastically at the end of World War I , and the Climax mine shut down in 1919. Molybdenum later found use in the metal alloys for the turbines of jet engines . Molybdenum is an important metal used in industrial work to increase the resistance of steel because of its much higher melting point compared to that of iron. Molybdenum was also used to fight weather erosion, friction, and chemical exposure of industrial equipment. The extraction of molybdenite hit its highest during World War I, when

8211-420: The forearc-hanging wall and not subducted. Most metamorphic phase transitions that occur within the subducting slab are prompted by the dehydration of hydrous mineral phases. The breakdown of hydrous mineral phases typically occurs at depths greater than 10 km. Each of these metamorphic facies is marked by the presence of a specific stable mineral assemblage, recording the metamorphic conditions undergone but

8330-485: The haulage of open-pit waste to the tailings dam, and hydromulching, among others. Climax also started the reclamation of a particular highly acidic tailing pond at the head of the Eagle River drainage. It sold the water rights to a company from Vail and started the process of removing and neutralizing the acid tailings to convert the pond to a freshwater reservoir. To do this, they used a “hydrology mining” process to extract

8449-430: The idea of subduction initiation at passive margins is popular, there is no modern day example for this type of subduction nucleation. This is likely due to the strength of the oceanic or transitional crust at the continental passive margins, suggesting that if the crust did not break in its first 20 million years of life, it is unlikely to break in the future under normal sedimentation loads. Only with additional weaking of

8568-493: The igneous bodies of the Climax Stock form a roughly circular structure. In cross-section view, each intrusion has an inverted bowl shape. Published studies on the origin of the Climax Molybdenum Deposit and other Climax-type moly deposits have concluded that they form principally in incipient extensional tectonic settings well inland from shallow-angle subduction zones that have recently ceased. The Climax deposit

8687-544: The incident to natural causes. In 2005, The New York Times reported that the company paid local military and police generals, colonels, majors and captains, and military units, a total of nearly US$ 20 million between 1998 and 2004. One individual received up to US$ 150,000. The payments were meant to secure the reserve. The company responded that the payments did not go to individuals, but went into infrastructure, food, housing, fuel, travel, vehicle repairs, and allowances to cover incidental and administrative costs. According to

8806-574: The lower plate occur when normal faults oceanward of the subduction zone are activated by flexure of the plate as it bends into the subduction zone. The 2009 Samoa earthquake is an example of this type of event. Displacement of the sea floor caused by this event generated a six-meter tsunami in nearby Samoa. Seismic tomography has helped detect subducted lithospheric slabs deep in the mantle where no earthquakes occur. About one hundred slabs have been described in terms of depth and their timing and location of subduction. The great seismic discontinuities in

8925-415: The mantle and is recycled. They are found at convergent plate boundaries, where the heavier oceanic lithosphere of one plate is overridden by the leading edge of another, less-dense plate. The overridden plate (the slab ) sinks at an angle most commonly between 25 and 75 degrees to Earth's surface. This sinking is driven by the temperature difference between the slab and the surrounding asthenosphere, as

9044-484: The mantle, at 410 km (250 mi) depth and 670 km (420 mi), are disrupted by the descent of cold slabs in deep subduction zones. Some subducted slabs seem to have difficulty penetrating the major discontinuity that marks the boundary between the upper mantle and lower mantle at a depth of about 670 kilometers. Other subducted oceanic plates have sunk to the core–mantle boundary at 2890 km depth. Generally, slabs decelerate during their descent into

9163-463: The mantle, from typically several cm/yr (up to ~10 cm/yr in some cases) at the subduction zone and in the uppermost mantle, to ~1 cm/yr in the lower mantle. This leads to either folding or stacking of slabs at those depths, visible as thickened slabs in seismic tomography. Below ~1700 km, there might be a limited acceleration of slabs due to lower viscosity as a result of inferred mineral phase changes until they approach and finally stall at

9282-465: The merger of Freeport Minerals , formerly Texas Freeport Sulphur Company and McMoRan Oil & Gas Company , becoming Freeport-McMoRan Inc. Freeport Sulphur Company was founded July 12, 1912, by the eldest son of Svante Magnus "E.M." Swenson , banker Eric Pierson Swenson, with a group of investors, to develop sulfur mining at Bryan Mound salt dome , along the US Gulf Coast . Freeport, Texas

9401-424: The mine ready in the event of market changes. In December 2007 Freeport-McMoRan reported that it planned to reopen the Climax mine and that production should start in 2010. An initial $ 500-million project involved the restart of open-pit mining and construction of state-of-the-art milling facilities. The company stated that the Climax mine had "... the largest, highest-grade and lowest-cost molybdenum ore body in

9520-491: The mine was declared fully operational. Officials at Bechtel , the primary project contractor, called mine development at Ertsberg "the most difficult engineering project they had ever undertaken." The challenges included building a 101-kilometre (63 mi) long access road (a project that required boring kilometer long tunnels through two mountains) and constructing the world's longest single span aerial tramway . The tramways were needed to move people, supplies and ore because

9639-532: The mine's early financial performance was disappointing. Depressed copper prices and high operating costs kept profits marginal during the 1970s. In 1967 The McMoRan Oil and Gas Company was founded by three partners, William Kennon McWilliams Jr. ("Mc"), James Robert (Jim Bob) Moffett ("Mo"), who were both petroleum geologists , and Mack Rankin ("Ran"), a specialist in land-leasing and sales operations. In 1981, McMoRab would merge with Freeport Minerals, formerly Freeport Sulphur, to form Freeport-McMoRan. In 1971,

9758-568: The mine. Freeport-McMoRan Freeport-McMoRan Inc. , often called Freeport , is an American mining company based in the Freeport-McMoRan Center , in Phoenix, Arizona . The company is the world's largest producer of molybdenum , a major copper producer and operates the world's largest gold mine , the Grasberg mine in Papua, Indonesia . The current company was created in 1981 through

9877-498: The new town's infrastructure led to the incorporation of a holding company on September 30, 1913, to join the newer assets with Freeport Sulphur. Officers of the new holding company, Freeport Texas Company , were: The new corporation's principal assets were listed as: In 1919, minority stockholders John R. Williams & Sons , First National Bank of Richmond, Virginia vice-president, W. M. Addison, Benjamin P Alsopp , E. L. Norton , and Samuel W. Travers solicited proxies to use at

9996-484: The ocean floor, studied the Mid-Atlantic Ridge and proposed that hot molten rock was added to the crust at the ridge and expanded the seafloor outward. This theory was to become known as seafloor spreading . Since the Earth's circumference has not changed over geologic time, Hess concluded that older seafloor has to be consumed somewhere else, and suggested that this process takes place at oceanic trenches , where

10115-429: The oldest oceanic lithosphere. Continental lithosphere is up to 200 km (120 mi) thick. The lithosphere is relatively cold and rigid compared with the underlying asthenosphere , and so tectonic plates move as solid bodies atop the asthenosphere. Individual plates often include both regions of the oceanic lithosphere and continental lithosphere. Subduction zones are where cold oceanic lithosphere sinks back into

10234-412: The overlying plate. If an eruption occurs, the cycle then returns the volatiles into the oceans and atmosphere. The surface expressions of subduction zones are arc-trench complexes. On the ocean side of the complex, where the subducting plate first approaches the subduction zone, there is often an outer trench high or outer trench swell . Here the plate shallows slightly before plunging downwards, as

10353-399: The overriding continent. When the lower plate subducts at a shallow angle underneath a continent (something called "flat-slab subduction"), the subducting plate may have enough traction on the bottom of the continental plate to cause the upper plate to contract by folding, faulting, crustal thickening, and mountain building. Flat-slab subduction causes mountain building and volcanism moving into

10472-510: The overriding plate. However, not all arc-trench complexes have an accretionary wedge. Accretionary arcs have a well-developed forearc basin behind the accretionary wedge, while the forearc basin is poorly developed in non-accretionary arcs. Beyond the forearc basin, volcanoes are found in long chains called volcanic arcs . The subducting basalt and sediment are normally rich in hydrous minerals and clays. Additionally, large quantities of water are introduced into cracks and fractures created as

10591-404: The planet. The ocean-ocean plate relationship can lead to subduction zones between oceanic and continental plates, therefore highlighting how important it is to understand this subduction setting. Although it is not fully understood what causes the initiation of subduction of an oceanic plate under another oceanic plate, there are three main models put forth by Baitsch-Ghirardello et al. that explain

10710-582: The possibility of spontaneous subduction from inherent density differences between two plates at specific locations like passive margins and along transform faults . There is evidence this has taken place in the Izu-Bonin-Mariana subduction system. Earlier in Earth's history, subduction is likely to have initiated without horizontal forcing due to the lack of relative plate motion, though a proposal by A. Yin suggests that meteorite impacts may have contributed to subduction initiation on early Earth. Though

10829-520: The pressures and temperatures necessary for this type of metamorphism are much higher than what is observed in most subduction zones. Frezzoti et al. (2011) propose a different mechanism for carbon transport into the overriding plate via dissolution (release of carbon from carbon-bearing minerals into an aqueous solution) instead of decarbonation. Their evidence comes from the close examination of mineral and fluid inclusions in low-temperature (<600 °C) diamonds and garnets found in an eclogite facies in

10948-469: The rainforest and two major rivers, on which they depend for their food, water, livelihoods, and traditions. Pressured by cultural and economic deterioration, there were numerous quarrels, between the tribes, Freeport, and the Indonesian military. Some unarmed natives were killed or tortured by the military, or became part of the Free Papua Movement insurgence. Subduction zone Subduction

11067-483: The report, anonymous sources within the company claimed that company chairman James R. Moffet courted Indonesia's dictator Suharto and "his cronies", cutting them in on deals. Another employee is said to have worked on a program to monitor environmentalists' telephone and email conversations, in collaboration with Indonesian military intelligence officers. The Grasberg mine's tailings "severely impacted" more than 11 square miles (28 km ) of rainforest, according to

11186-473: The rock above to break and drop down in a controlled manner. The method allowed economical extraction of the large low-grade ore deposit. Current mining operations at Climax are via an open-pit. The ore is crushed on-site, and the molybdenite is separated from the waste material by froth flotation , which mixes pulverized ore into a slurry of air, water, surfactants , and other chemicals. The large quantities of waste slurry flows into nearby reservoirs on

11305-507: The rock contained no gold or silver, but retained the claims. The following year he settled with his Ute wife a few miles north, and made a living working a nearby gold placer. Each year he performed the assessment work required to maintain his lode claims, convinced that his mystery mineral must be of value. In 1918 Senter received US$ 40,000 for his mining claims and "settled into a comfortable retirement in Denver." Although Senter finally found

11424-444: The rocks of the mantle. The mantle-derived magmas (which are initially basaltic in composition) can ultimately reach the Earth's surface, resulting in volcanic eruptions. The chemical composition of the erupting lava depends upon the degree to which the mantle-derived basalt interacts with (melts) Earth's crust or undergoes fractional crystallization . Arc volcanoes tend to produce dangerous eruptions because they are rich in water (from

11543-436: The sedimentary and volcanic cover is mostly scraped off to form an orogenic wedge. An orogenic wedge is larger than most accretionary wedges due to the volume of material there is to accrete. The continental basement rocks beneath the weak cover suites are strong and mostly cold, and can be underlain by a >200 km thick layer of dense mantle. After shedding the low density cover units, the continental plate, especially if it

11662-450: The sinking oceanic plate they are attached to. Where continents are attached to oceanic plates with no subduction, there is a deep basin that accumulates thick suites of sedimentary and volcanic rocks known as a passive margin. Some passive margins have up to 10 km of sedimentary and volcanic rocks covering the continental crust. As a passive margin is pulled into a subduction zone by the attached and negatively buoyant oceanic lithosphere,

11781-453: The slab and sediments) and tend to be extremely explosive. Krakatoa , Nevado del Ruiz , and Mount Vesuvius are all examples of arc volcanoes. Arcs are also associated with most ore deposits. Beyond the volcanic arc is a back-arc region whose character depends strongly on the angle of subduction of the subducting slab. Where this angle is shallow, the subducting slab drags the overlying continental crust partially with it, which produces

11900-447: The storage of carbon through silicate weathering processes. This storage represents a carbon sink , removing carbon from the atmosphere and resulting in global cooling. Their study correlates several Phanerozoic ophiolite complexes, including active arc-continent subduction, with known global cooling and glaciation periods. This study does not discuss Milankovitch cycles as a driver of global climate cyclicity. Modern-style subduction

12019-481: The stratosphere during violent eruptions can cause rapid cooling of Earth's climate and affect air travel. Arc-magmatism plays a role in Earth's Carbon cycle by releasing subducted carbon through volcanic processes. Older theory states that the carbon from the subducting plate is made available in overlying magmatic systems via decarbonation, where CO 2 is released through silicate-carbonate metamorphism. However, evidence from thermodynamic modeling has shown that

12138-526: The subducting slab bends downward. During the transition from basalt to eclogite, these hydrous materials break down, producing copious quantities of water, which at such great pressure and temperature exists as a supercritical fluid . The supercritical water, which is hot and more buoyant than the surrounding rock, rises into the overlying mantle, where it lowers the melting temperature of the mantle rock, generating magma via flux melting . The magmas, in turn, rise as diapirs because they are less dense than

12257-500: The subducting slab. Transitions between facies cause hydrous minerals to dehydrate at certain pressure-temperature conditions and can therefore be tracked to melting events in the mantle beneath a volcanic arc. Two kinds of arcs are generally observed on Earth: island arcs that form on the oceanic lithosphere (for example, the Mariana and the Tonga island arcs), and continental arcs such as

12376-451: The subject, performs the action of overriding the object, the lower plate, which is overridden. Subduction zones are important for several reasons: Subduction zones have also been considered as possible disposal sites for nuclear waste in which the action of subduction itself would carry the material into the planetary mantle , safely away from any possible influence on humanity or the surface environment. However, that method of disposal

12495-452: The subsidence area covered about 100 acres on Bartlett mountain. Around the open-pit, caved ground combined with winter avalanches and high vertical pit walls make the West side of the mountain even more susceptible to collapse. Also, the cracks through the rocks created by shifting blocks allow ground water to infiltrate into the working tunnels, increasing the potential for acid rock drainage from

12614-454: The surface once the volcanoes have weathered away. The volcanism and plutonism occur as a consequence of the subducting oceanic slab dehydrating as it reaches higher pressures and temperatures. Once the oceanic slab reaches about 100 km in depth, hydrous minerals become unstable and release fluids into the asthenosphere. The fluids act as a flux for the rock within the asthenosphere and cause it to partially melt. The partially melted material

12733-525: The tailings from the bedrock it had been sitting on for several decades. This process converted the compacted tailings to a water slurry that could be easily piped into a pond where it would be chemically neutralized. In 1994, the mine labor force was reduced to 24 employees who were working on five different tasks, including treating water and maintaining environmental quality, environmental reclamation and development of water resources. Ground surface subsidence started around 1920 on Bartlett mountain. By 2001,

12852-496: The takeover process. The Indonesian government finalized the process on December 21, 2018. Freeport is the world's largest producer of molybdenum , and one of the largest producers of copper. In 2019, 79% of its revenues were from the sale of copper , 11% were from the sale of gold , and 8% were from the sale of molybdenum . In 2019, sales to the company's copper refining joint venture in Gresik Regency accounted for 13% of

12971-439: The timing and conditions in which these dehydration reactions occur is key to interpreting mantle melting, volcanic arc magmatism, and the formation of continental crust. A metamorphic facies is characterized by a stable mineral assemblage specific to a pressure-temperature range and specific starting material. Subduction zone metamorphism is characterized by a low temperature, high-ultrahigh pressure metamorphic path through

13090-516: The total revenues of the company. Some of the company's mining operations are as follows: Freeport Cobalt held a 100% interest in Kisanfu, a copper and cobalt exploration project located near Tenke, Democratic Republic of the Congo. This subsidiary also owns a large cobalt refinery in Kokkola , Finland, along with a related sales and marketing business. FCX has an effective 56% of that enterprise. Negotiations in 2016 to include these cobalt projects in

13209-444: The trench and approximately one hundred kilometers above the subducting slab. Arcs produce about 10% of the total volume of magma produced each year on Earth (approximately 0.75 cubic kilometers), much less than the volume produced at mid-ocean ridges, but they have formed most continental crust . Arc volcanism has the greatest impact on humans because many arc volcanoes lie above sea level and erupt violently. Aerosols injected into

13328-400: The underlying ductile mantle . This process of convection allows heat generated by radioactive decay to escape from the Earth's interior. The lithosphere consists of the outermost light crust plus the uppermost rigid portion of the mantle . Oceanic lithosphere ranges in thickness from just a few km for young lithosphere created at mid-ocean ridges to around 100 km (62 mi) for

13447-450: The world.". The remaining ore reserves are estimated to contain about 500 million pounds of molybdenum, contained in ore at an average molybdenum percentage of 0.165%. Production was expected to be about 30 million pounds per year, starting in 2010. Due to lower molybdenum prices, Freeport-McMoRan announced in November 2008 that it was deferring the plan to reopen the Climax mine. At the time,

13566-757: Was accused of negligence by the Indonesian National Human Rights Commission. The company is a signatory participant of the Voluntary Principles on Security and Human Rights . However, the company has been accused of funding the Indonesian government to secure its reserve through militaristic oppression of the native West Papuan people. Freeport has had a troubled relationship with the Amungme and Kamoro peoples since it arrived in Indonesia in 1967. Freeport allegedly damaged 30.000 hectares of

13685-773: Was also established in Nov. 1912 to house workers, and serve as a port for Houston, rivaling Galveston and Corpus Christi. Freeport mined sulfur along the Gulf Coast using the Frasch Process , the patents for which had expired in 1912. Previously, Union Sulphur Company founder and patent-holder Herman Frasch had enjoyed a monopoly on the process. The company became known as Freeport Sulphur , later changing its corporate name to Freeport Minerals . In 1922, Freeport started producing sulfur from Hoskins Mound in Brazoria County, Texas . Enterprise to support Freeport Sulphur's business and

13804-607: Was caused by subduction of the Indo-Australian plate under the Euro-Asian Plate, but the tsunami spread over most of the planet and devastated the areas around the Indian Ocean. Small tremors which cause small, nondamaging tsunamis, also occur frequently. A study published in 2016 suggested a new parameter to determine a subduction zone's ability to generate mega-earthquakes. By examining subduction zone geometry and comparing

13923-414: Was fined by the U.S. Department of Labor's Mine Safety and Health Administration over the death of a miner. The 67-year-old man had fallen into a hole created by the removal of two steel gratings. It was concluded that Freeport had not done enough to indicate that the hole was there. The company operates the world's largest and most profitable gold mine, the Grasberg mine in Papua, Indonesia . In 2003,

14042-563: Was once hotter, but not that subduction conditions were hotter. Previously, the lack of pre-Neoproterozoic blueschist was thought to indicate a different type of subduction. Both lines of evidence refute previous conceptions of modern-style subduction having been initiated in the Neoproterozoic Era 1.0 Ga ago. Harry Hammond Hess , who during World War II served in the United States Navy Reserve and became fascinated in

14161-439: Was the catalyst that developed Port Sulphur, Louisiana . The company produced nickel during World War II and potash in the 1950s. In 1955, Freeport Nickel invested $ 119 million, of which $ 100 million came from the U.S. government, into construction of a nickel- cobalt mine at Moa Bay, Cuba , and a refinery at Port Nickel, Louisiana . On March 11, 1957, the U.S. government announced a contract to buy nickel and cobalt from

#474525