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67-486: Pebble Mine is the common name of a proposed copper -gold- molybdenum mining project in the Bristol Bay region of Southwest Alaska, near Lake Iliamna and Lake Clark . It was discovered in 1987, optioned by Northern Dynasty Minerals in 2001, explored in 2002, and drilled from 2002-2013 with discovery in 2005. Preparing for the permitting process began and administrative review lasted over 13 years. As of November 2020

134-618: A 9.9% ownership of Northern Dynasty Minerals Limited in July, 2006, and in 2007 doubled that to 19.8% ownership, for an additional 94 million dollars. On December 23, 2013, Rio Tinto announced it reviewed its $ 200 million investment in Northern Dynasty Minerals, and considered divesting. On April 7, 2014, Rio Tinto divided its 19% holdings in the project equally between the Bristol Bay Native Corporation, which had opposed

201-525: A South African mining company, struck a deal with Northern Dynasty to earn a 50% interest in a newly created Pebble Limited Partnership, the other 50% belonging to Northern Dynasty; between 2007 and 2013 Anglo American spent over half a billion dollars on the project. In December 2013 Anglo American walked away from the project, losing its 50% interest, which reverted to Northern Dynasty Minerals Limited. Rio Tinto Group , through its wholly owned subsidiary Kennecott Utah Copper purchased, for 87 million dollars,

268-645: A Vancouver-based Canadian mining corporation. All but one of Hunter Dickinson Corporation's board members are also on the Northern Dynasty board. Most of the senior management of Northern Dynasty also hold senior management positions at Hunter Dickinson Corporation. As reported on February 13, 2019, Kopernik Global Investors beneficially owns 6.17% of Northern Dynasty Minerals, which is an increase of 11% in their ownership stake from their prior reported position reported in February, 2018. Based on filings, Kopernik has held

335-441: A complex of several small granodiorite cupolas , diorite sills , older intrusions, breccias , and sediments. The western part of the deposit is locally exposed at the surface; thin gossans are developed and oxidation reaches 100 feet (30 m) in depth. The orebody extends eastward across a fault contact, at depth. East of the fault mineralization occurs in abundant sills and in the intruded sediments. Farther east, and deeper,

402-522: A given time differentiated magmas would burst violently out of these fault-traps and head to shallower places in the crust where porphyry copper deposits would be formed. Characteristics of porphyry copper deposits include: Porphyry copper deposits are typically mined by open-pit methods. Copper is not the only metal that occurs in porphyry deposits. There are also porphyry ore deposits mined primarily for molybdenum , many of which contain very little copper. Examples of porphyry molybdenum deposits are

469-561: A position in NAK since at least as early as 2015, when they owned 19.99%. Pebble is the largest known undeveloped copper ore body in the world, measured by either the amount of contained metal or the amount of ore. A report released by Northern Dynasty in 2011 predicted profits for mine owners from a large-scale open-pit mine at Pebble, given appropriate assumptions about construction costs ($ 4.7 billion), scale (200,000 tons per day), lifetime (45 years), metal prices over that lifetime (2011 prices) and

536-460: Is described as "a rock of intermediate composition between quartz diorite and quartz monzonite ". Plymouth Rock is a glacial erratic boulder of granodiorite. The Sierra Nevada mountains contain large sections of granodiorite. Granodiorite was quarried at Mons Claudianus in the Red Sea Governorate in eastern Egypt from the 1st century AD to the mid-3rd century AD. Much of

603-525: Is evidenced by the fact that most examples of granodiorite sculpture seem to have come from later dates. However, its presence in the Rosetta Stone implies that they had considerable experience with it and the fact that only newer artifacts are found may simply be because earlier pieces were lost. Granodiorite is quarried in the Newry area of County Armagh with the common name of 'Newry granite'. Granodiorite

670-419: Is home to the world's largest commercial sockeye salmon fishery. The Kvichak River has the world's single largest sockeye run. The Kvichak drains from Lake Iliamna, which is downstream of the deposit. Salmon, herring and other fisheries account for nearly 75% of local jobs. Sport fishing is another important local industry. Many lodges cater for sport fishermen exploiting the salmon and trout populations in

737-461: Is hosted in porphyritic granodiorite to tonalite of Upper Cretaceous age intruded into deformed sedimentary rocks of the Jurassic to Cretaceous Kahiltna flysch terrane . The copper ore is a calc-alkali porphyry copper -gold-molybdenum deposit. The ore body extends from the surface to at least 1,700 metres (5,600 ft) depth. In the western part of the orebody, mineralization occurs in

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804-554: Is now 100% owned by The Northern Dynasty Partnership, which is a wholly owned Canadian-based subsidiary of Northern Dynasty Minerals, Limited. Three of the world's largest mining companies purchased shares of Northern Dynasty or became partners in the Pebble Limited Partnership through obligations to fund exploration and development. All have since divested their interests. Mitsubishi Corporation sold its 9.1% interest in Northern Dynasty Minerals in 2011. Anglo American,

871-680: Is some form of geodynamic control or crustal influence affecting the location of porphyry formation. Porphyry deposits tend to occur in linear, orogen -parallel belts (such as the Andes in South America ). There also appear to be discrete time periods in which porphyry deposit formation was concentrated or preferred. 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

938-475: Is sometimes used informally for various rocks ranging from granite to diorite , including granodiorite. According to the QAPF diagram , granodiorite has a greater than 20% quartz by volume, and between 65% and 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as tonalite . Granodiorite is felsic to intermediate in composition. It is the intrusive igneous equivalent of

1005-445: Is that the generation of andesitic magmas is multistage, and involves crustal melting and assimilation of primary basaltic magmas, magma storage at the base of the crust ( underplating by dense, mafic magma as it ascends), and magma homogenization. The underplated magma will add a lot of heat to the base of the crust, thereby inducing crustal melting and assimilation of lower-crustal rocks, creating an area with intense interaction of

1072-705: Is within Lake and Peninsula Borough , about 1,600 inhabitants as of United States Census, 2010 , adjacent to the Bristol Bay Borough of about 1000 inhabitants and the Dillingham Census Area , 4,800 inhabitants. Some 7,500 people live largely rural lifestyles within or near the area downstream of the Pebble site. The populations of Lake Clark National Park and other parts of the Bethel Census Area are upstream of

1139-766: The Climax , Urad, Mt. Emmons, and Henderson deposits in central Colorado ; the White Pine and Pine Grove deposits in Utah; the Questa deposit in northern New Mexico ; and Endako in British Columbia. The US Geological Survey has classed the Chorolque and Catavi tin deposits in Bolivia as porphyry tin deposits . Some porphyry copper deposits in oceanic crust environments, such as those in

1206-734: The Latin grānum for " grain ", an English language derivative. Diorite is named after the contrasting colors of the rock. Banatite is a term used informally for various rocks ranging from granite to diorite , but often granodiorite, that were intruded in the Late Cretaceous in the Banat and nearby regions of present-day Hungary and Serbia . The term is also used in Australia in connection with Gulaga / Mount Dromedary in New South Wales , where it

1273-938: The Pacific Ring of Fire ; the Caribbean ; southern central Europe and the area around eastern Turkey ; scattered areas in China , the Mideast , Russia , and the CIS states ; and eastern Australia . Only a few are identified in Africa , in Namibia and Zambia ; none are known in Antarctica . The greatest concentration of the largest copper porphyry deposits is in northern Chile . Almost all mines exploiting large porphyry deposits produce from open pits . Porphyry copper deposits represent an important resource and

1340-524: The Philippines , Indonesia , and Papua New Guinea , are sufficiently rich in gold that they are called copper-gold porphyry deposits. Granodiorite Granodiorite ( / ˌ ɡ r æ n oʊ ˈ d aɪ . ə r aɪ t , ˌ ɡ r æ n ə ˈ -/ GRAN -oh- DY -ə-ryte, GRAN -ə- ) is a coarse-grained ( phaneritic ) intrusive igneous rock similar to granite , but containing more plagioclase feldspar than orthoclase feldspar . The term banatite

1407-668: The extrusive igneous dacite . It contains a large amount of sodium (Na) and calcium (Ca) rich plagioclase, potassium feldspar , quartz , and minor amounts of muscovite mica as the lighter colored mineral components. Biotite and amphiboles often in the form of hornblende are more abundant in granodiorite than in granite, giving it a more distinct two-toned or overall darker appearance. Mica may be present in well-formed hexagonal crystals, and hornblende may appear as needle-like crystals. Minor amounts of oxide minerals such as magnetite , ilmenite , and ulvöspinel , as well as some sulfide minerals may also be present. On average,

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1474-519: The mantle magma and crustal magma. This progressively evolving magma will become enriched in volatiles, sulfur, and incompatible elements – an ideal combination for the generation of a magma capable of generating an ore deposit. From this point forward in the evolution of a porphyry deposit, ideal tectonic and structural conditions are necessary to allow the transport of the magma and ensure its emplacement in upper-crustal levels. Although porphyry deposits are associated with arc volcanism , they are not

1541-547: The partial melting of the upper part of post-subduction, stalled slabs that are altered by seawater. Shallow subduction of young, buoyant slabs can result in the production of adakitic lavas via partial melting. Alternatively, metasomatised mantle wedges can produce highly oxidized conditions that results in sulfide minerals releasing ore minerals (copper, gold, molybdenum), which are then able to be transported to upper crustal levels. Mantle melting can also be induced by transitions from convergent to transform margins, as well as

1608-600: The EIS did not consider habitat destruction that could lead to destruction of salmon stocks in Bristol Bay. The legal director of Trustees for Alaska, a nonprofit public interest law firm, indicated that the report was "lacking and thoroughly inadequate." The mine itself would be an open-pit mine a mile square in area and a third of a mile deep. Ponds would be dammed to contain tailing, including some toxic materials. A 165-mile natural gas pipeline would be constructed to provide power for

1675-731: The Newhalen River to Lake Iliamna. The Kahiltna terrain is interpreted to represent a sediment trough formed on the landward (Alaska) side of the Wrangellia volcanic arc terrane, prior to collision of Wrangellia with Alaska. The Wrangellia and Kahiltna terrains docked to Alaska in the Cretaceous Period. This part of the Kahiltna terrane is dominated by Late Triassic basalt , andesite and sedimentary rocks overlain by Jurassic-Cretaceous andesitic turbidites. Cretaceous granitic intrusive activity

1742-671: The Pebble East deposit and acquired 100% ownership of the Pebble mining claims. In 2008, $ 140 million was budgeted and approximately 150,000 feet (46,000 m) of additional drilling was completed. In 2009, $ 70 million was budgeted, to complete a preliminary feasibility study, or "prefeasibility" study, and to prepare the project for permitting. In 2010, $ 73 million was budgeted towards the pre-feasibility report, environmental studies, and various administrative and community-relations work. Applications for development and operations permits were not planned until after 2010. For 2011, $ 91 million

1809-557: The Pebble West occurrence (originally named Pebble Beach) was part of a large copper porphyry system. CAE continued drilling and other work through 1992, with a second drill campaign in 1997, with the resource doubled from 500M short tons to 1B short tons. In 2001, Northern Dynasty Minerals, Ltd. optioned the property from Teck Cominco , the successor to CAE's parent company. Northern Dynasty Minerals began exploration in 2002, which continued through 2013. In 2005, Northern Dynasty discovered

1876-464: The Pebble mine could cross 20 known salmon streams), and general water pollution-related concerns. The U.S. Environmental Protection Agency (EPA) began conducting a scientific review of the Bristol Bay watershed in 2011 focused on the Nushagak and Kvichak river drainages, in response to petitions from tribes, commercial fishing organizations, and other organizations opposed to Pebble. The agency completed

1943-554: The annual throughput of drinking-quality water at the Anchorage Waste and Wastewater Utility. In April 2017 Northern Dynasty reported that it had received notice of approval of a Miscellaneous Land Use Permit from the Alaska Department of Natural Resources (DNR) for ongoing activities at Pebble. Site-specific baseline data and scientific studies of potential environmental and social effects have been and are being conducted by

2010-489: The area. In 1987 Cominco Alaska Exploration (CAE) (which subsequently became Teck Resources ) collected mineralized surface samples at the Pebble site from color anomalies visible from aircraft. Geologist Phil St. George was credited with the discovery. He led early exploration efforts, drilling out the first half billion tons of the deposit. The first two exploration holes were drilled in 1988; in 1989 twelve more drill holes, soil sampling, and geophysical surveys indicated that

2077-413: The construction of railroads, and a surge in market demand near the start of the 20th century. Some mines exploit porphyry deposits that contain sufficient gold or molybdenum, but little or no copper. Porphyry copper deposits are currently the largest source of copper ore. Most of the known porphyry deposits are concentrated in: western South and North America and Southeast Asia and Oceania – along

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2144-450: The crust, of which there are 574 known deposits that are at the surface. It is estimated that the Earth's porphyry copper deposits contain approximately 1.7×10 tonnes of copper, equivalent to more than 8,000 years of global mine production. Porphyry deposits represent an important resource of copper; however, they are also important sources of gold and molybdenum – with porphyry deposits being

2211-553: The dominant source of copper that is mined today to satisfy global demand. Via compilation of geological data, it has been found that the majority of porphyry deposits are Phanerozoic in age and were emplaced at depths of approximately 1 to 6 kilometres with vertical thicknesses on average of 2 kilometres. Throughout the Phanerozoic an estimated 125,895 porphyry copper deposits were formed; however, 62% of them (78,106) have been removed by uplift and erosion. Thus, 38% (47,789) remain in

2278-413: The dominant source of the latter. In general, porphyry deposits are characterized by low grades of ore mineralization, a porphyritic intrusive complex that is surrounded by a vein stockwork and hydrothermal breccias . Porphyry deposits are formed in arc-related settings and are associated with subduction zone magmas. Porphyry deposits are clustered in discrete mineral provinces, which implies that there

2345-637: The fault and its splays are unknown in the Pebble area, due to extensive ground cover. A 2007 report indicates that magnitude 7.1 quakes occur on the fault on a 700-year cycle. The Lake Clark fault several hundred miles to the north is sub-parallel to the Denali fault and considered to be of similar nature. A magnitude 7.9 quake struck the Denali fault in 2002. The subduction zone of the Aleutian Trench lies approximately 125 miles (200 km) south of Pebble. This zone

2412-729: The flats. Pebble is under a broad flat valley at about 1,000 feet (300 m) above sea level dividing the drainages of Upper Talarik Creek and the Koktuli River. Upper Talarik Creek flows into Lake Iliamna, which flows through the Kvichak River into Bristol Bay. Waters in the Koktuli River drain into the Mulchatna River , a tributary of the Nushagak River which empties into Bristol Bay at Dillingham . Water from Lake Clark , approximately 20 miles (32 km) east of Pebble, flows down

2479-620: The formation of porphyry deposits in the south-west Pacific, after a collisional event. Arc reversal occurs due to collision between an island arc and either another island arc, a continent, or an oceanic plateau. The collision may result in the termination of subduction and thereby induce mantle melting. Porphyry deposits do not generally have any requisite structural controls for their formation; although major faults and lineaments are associated with some. The presence of intra-arc fault systems are beneficial, as they can localize porphyry development. Furthermore, some authors have indicated that

2546-419: The freshwater tributaries. Freshwater species include humpback whitefish ( Coregonus pidschianpp ), Dolly Varden trout ( Salvelinus malma ), arctic grayling ( Thymallus arcticus ) and rainbow trout ( Oncorhynchus mykiss ). Seasonal harvesting of salmon and year-round harvesting of freshwater fish is a critical part of life for rural residents, most of whom live downstream of the mine site. The Pebble site

2613-419: The generation of porphyry deposits. Initially, there will be decreased alkalic magmatism, horizontal shortening, hydration of the lithosphere above the flat-slab, and low heat flow. Upon a return to normal subduction, the hot asthenosphere will once again interact with the hydrated mantle, causing wet melting, crustal melting will ensue as mantle melts pass through, and lithospheric thinning and weakening due to

2680-690: The increased heat flow. The subducting slab can be lifted by aseismic ridges, seamount chains, or oceanic plateaus – which can provide a favourable environment for the development of a porphyry deposit. This interaction between subduction zones and the aforementioned oceanic features can explain the development of multiple metallogenic belts in a given region; as each time the subduction zone interacts with one of these features it can lead to ore genesis. Finally, in oceanic island arcs, ridge subduction can lead to slab flattening or arc reversal; whereas, in continental arcs it can lead to periods of flat slab subduction . Arc reversal has been shown to slightly pre-date

2747-457: The initial claim staking by Cominco in 1987. The Pebble Limited Partnership was once one of the largest multinational mining corporations made up of South African company Anglo American, along with Northern Dynasty Minerals, a junior mining company headquartered in Canada. After a few investors walked away, Northern Dynasty was the only company left seeking development. The Pebble Limited Partnership

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2814-809: The majority of large porphyry deposits are associated with calc-alkaline intrusions, although some of the largest gold-rich deposits are associated with high-K calc-alkaline magma compositions. Numerous world-class porphyry copper-gold deposits are hosted by high-K or shoshonitic intrusions, such as Bingham copper-gold mine in USA, Grasberg copper-gold mine in Indonesia, Northparkes copper-gold mine in Australia, Oyu Tolgoi copper-gold mine in Mongolia and Peschanka copper-gold prospect in Russia. The magmas responsible for porphyry formation are conventionally thought to be generated by

2881-420: The mine design plan. The study assumed a slurry pipeline would deliver ore concentrate from the mine to a new port on Cook Inlet, and that trucks will haul ore concentrates to Cook Inlet. The plan expected the mine to return the initial capital investment in 3.2 years, employ over a thousand people for the first 25 years and provide a lifetime 23.2% pretax internal rate of return . The expected pretax cash flow

2948-521: The mine developer, Northern Dynasty Minerals, still sought federal permits from the United States Coast Guard and the Bureau of Safety and Environmental Enforcement . State permitting would then follow, which the developer expected to take up to three years. In November 2020, the U.S. Army Corps of Engineers (USACE) denied a permit for the proposed mine discharge plan. On September 9, 2021, it

3015-596: The mine, and the Alaska Community Foundation, which had cooperated with Northern Dynasty in managing the Pebble Fund, a financier of grants to organizations in the Bristol Bay area. In April 2014, the Rio Tinto Group gifted its shares, worth only approximately 18 million by then, to two Alaskan charitable foundations. Northern Dynasty is one of several public mining companies controlled by Hunter Dickinson,

3082-534: The occurrence of intersections between continent-scale traverse fault zones and arc-parallel structures are associated with porphyry formation. This is actually the case of Chile's Los Bronces and El Teniente porphyry copper deposits each of which lies at the intersection of two fault systems. It has been proposed that "misoriented" deep-seated faults that were inactive during magmatism are important zones where porphyry copper-forming magmas stagnate allowing them to achieve their typical igneous differentiation . At

3149-413: The operation, as well as 80 miles of road and pipeline to transport the mined concentrate to Cook Inlet . Operating the mine would use and impound large amounts of surface water. The roads would carry fuel, industrial chemicals and supplies. Porphyry copper deposit The first mining of low-grade copper porphyry deposits from large open pits coincided roughly with the introduction of steam shovels,

3216-507: The potential to invest up to $ 47 million total over a two-year period. The land is owned by the State of Alaska. Pebble Mines Corp. holds mineral rights for 186 square miles (480 km) of the area, an area that includes the Pebble deposits, as well as other, less explored, mineral deposits. A sequence of mining companies and partnerships have owned the Alaska mining claims at and around Pebble since

3283-418: The project operators and their consultants. These studies address water quality and other concerns. Among these are: Public interest in the project has also resulted in outside, and opposing, interests publishing scientific reviews of available data and comparisons with other projects. These include reports or summaries on the following: acid rock drainage, effects of roads and bridges on fish (roads supporting

3350-562: The quarried stone was transported to Rome for use in major projects such as the Pantheon and Hadrian's Villa . Additionally, granodiorite was used for the Rosetta Stone . The extent of Egyptian granodiorite masonry is unclear. Egypt's 6000-year history makes determining the period of usage difficult as well. Perhaps like porphyry , it was ignored by the successive dynasties of Egypt and only heavily mined during Ptolemaic or Roman times. This

3417-518: The resource (at 100% recovery) were 56.9 billion pounds of copper, 70.6 million troy ounces of gold, 3.4 billion pounds of molybdenum and 344 million ounces of silver. The estimate used a 0.3% copper equivalent cutoff. As of August 2021 gross value of the contained metals, 57% was from copper, and 27% from gold and 14% from molybdenum. Co-products including silver, rhenium, and palladium might also be recoverable. All five Eastern Pacific salmon species spawn in Bristol Bay's freshwater tributaries. The bay

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3484-607: The review in 2014. See Legal challenges . The U.S. Army Corps of Engineers (USACE) released its final Environmental impact statement (EIS) for the Pebble Mine project in July 2020, concluding that the project would not lead to "long-term changes in the health of the commercial fisheries in Bristol Bay," under normal conditions. After a preliminary draft of this final statement was sent to federal and state agencies, many other scientific and administrative groups critiqued this conclusion. The U.S. Fish and Wildlife Service stated that

3551-620: The sills coalesce into a deeply buried granodiorite pluton . Mineralization and ore continue into the pluton. The eastern part of the deposit was eroded when it was exposed at the surface millions of years ago. It has since been buried by a thickening-to-the-east wedge of post-mineralization-age Tertiary sedimentary and volcanic sedimentary rocks. Mineralization at Pebble is aged from 90.4 ±0.6 MYA to 89.5 ±0.3 MYA. Metallic minerals identified at Pebble include pyrite , chalcopyrite , molybdenite , and bornite , along with minor covellite , chalcocite , digenite and magnetite . In 2008, Pebble

3618-415: The site or in a different watershed. The populations in the area rely heavily on wild resources for subsistence, harvesting moose , caribou and salmon. Wild resources play an important part in the region's cultural heritage. There are more than 30 Alaskan native tribes in the region that depend on salmon to support their traditional subsistence ways of life, in addition to other inhabitants and tourists in

3685-437: The skewed distribution towards most deposits being less than 20 million years is at least partially an artifact of exploration methodology and model assumptions, as large examples are known in areas which were previously left only partially or under-explored partly due to their perceived older host rock ages, but which were then later found to contain large, world-class examples of much older porphyry copper deposits. In general,

3752-457: The steepening and trenchward retreat of the subducted slab. However, the latest belief is that dehydration that occurs at the blueschist - eclogite transition affects most subducted slabs, rather than partial melting. After dehydration, solute-rich fluids are released from the slab and metasomatise the overlying mantle wedge of MORB -like asthenosphere , enriching it with volatiles and large ion lithophile elements (LILE). The current belief

3819-417: The surrounding rock, thus concentrating the fluid into a single stock, and 5) rapid uplift and erosion promotes decompression and efficient, eventual deposition of ore. Porphyry deposits are commonly developed in regions that are zones of low-angle (flat-slab) subduction . A subduction zone that transitions from normal to flat and then back to normal subduction produces a series of effects that can lead to

3886-656: The time period ranging from the middle Miocene to the Recent period, however notable exceptions are known. Most large-scale porphyry deposits have an age of less than 20 million years, however there are notable exceptions, such as the 438 million-year-old Cadia-Ridgeway deposit in New South Wales. This relatively young age reflects the preservation potential of this type of deposit; as they are typically located in zones of highly active tectonic and geological processes, such as deformation, uplift, and erosion. It may be however, that

3953-466: The typical products in that environment. It is believed that tectonic change acts as a trigger for porphyry formation. There are five key factors that can give rise to porphyry development: 1) compression impeding magma ascent through crust, 2) a resultant larger shallow magma chamber , 3) enhanced fractionation of the magma along with volatile saturation and generation of magmatic-hydrothermal fluids, 4) compression restricts offshoots from developing into

4020-452: The upper continental crust has the same composition as granodiorite. Granodiorite is a plutonic igneous rock, formed by intrusion of silica-rich magma , which cools in batholiths or stocks below the Earth's surface. It is usually only exposed at the surface after uplift and erosion have occurred. The name comes from two related rocks to which granodiorite is an intermediate: granite and diorite . The gran- root comes from

4087-414: The villages of Nondalton , Newhalen , and Iliamna . The site is 200 miles (320 km) southwest of Anchorage, Alaska. Pebble is approximately 15 miles (24 km) north of, and upstream of, Lake Iliamna , and near Lake Clark . The deposit area is characterized by relatively flat land dotted by glacial ponds, interspersed with isolated mountains or ranges of hills rising one or two thousand feet above

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4154-467: Was approximately $ 2 billion per year for much of the mine life and significantly more during the later years. The report states that 58% of the ore resource will remain at year 45. Northern Dynasty has applied for water rights permits to Upper Talarik Creek and the Koktuli River for use in mining. Altogether, Northern Dynasty has applied for rights to about 35 billion US gallons (130,000,000 m) of ground and surface water per year, about four times

4221-432: Was budgeted to complete the pre-feasibility study, leading to permit applications in 2012. Environmental and engineering studies including 45,000 feet (14,000 m) of drilling to decide on mine design and a complete environmental baseline. By 2017, over $ 150 million had been spent on environmental and social impact assessments. In 2022, an additional $ 9.4 million was received from a private asset management company, with

4288-466: Was estimated to be the second-largest ore deposit of its type in the world in terms of the value of the contained metal, slightly smaller than Indonesia's Grasberg Mine , which contains more metal in a smaller amount of ore than Pebble. The last resource estimate for Pebble, as at December 2017, was a measured and indicated resource of 6.46 billion tonnes of ore grading 0.40% copper, 0.34 g/t gold, 1.7 g/t silver and 240 ppm molybdenum. Contained metals in

4355-685: Was reported that the United States Environmental Protection Agency had "asked a federal court to allow for Clean Water Act protections for parts of the bay." On January 31, 2023, the EPA effectively vetoed the project, using a rarely invoked power to restrict development to protect watersheds. The Pebble prospect is in a remote, wild, and generally uninhabited part of the Bristol Bay watershed in Southwest Alaska. The nearest communities, about 20 miles (32 km) distant, are

4422-413: Was the source of the 1964 Good Friday earthquake of magnitude 9.2. The Augustine Volcano , which lies 25 miles offshore, last erupted in 2006. A contiguous body of ore is known as Pebble West where mineralization locally extends to the surface and as Pebble East where it is deeply buried. Pebble holds mostly low-grade ore, requiring a large-scale operation to economically recover it. The Pebble deposit

4489-497: Was widespread in the Kahiltna terrane. Tertiary volcanic and sedimentary rocks, and Quaternary glacial deposits, developed over the older rocks. The Lake Clark fault, or a splay, probably lies within twenty miles (32 km) of the Pebble deposits and possibly much closer. The fault is a major right-lateral strike-slip crustal feature, considered to be a westward expression of the Castle Mountain fault. The actual ground trace of

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