| Heart Peaks | |
|---|---|
 Satellite photo of Heart Peaks (middle) | |
| Highest point | |
| Elevation | 2,012 m (6,601 ft) |
| Prominence | 1,012 m (3,320 ft) |
| Coordinates | 58°35′56″N131°57′48″W / 58.59889°N 131.96333°W /58.59889; -131.96333 |
| Geography | |
  Heart Peaks Location of Heart Peaks in British Columbia | |
| Location | British Columbia, Canada |
| Parent range | Nahlin Plateau |
| Topo map | NTS104J12Dudidontu River[1] |
| Geology | |
| Rock age | Neogene-to-Quaternary[2] |
| Mountain type | Shield volcano[3] |
| Volcanic zone | Northern Cordilleran Volcanic Province[2] |
| Last eruption | Unknown[3] |
Heart Peaks, originally known as theHeart Mountains, is amountainmassif in theNorthern Interior ofBritish Columbia, Canada. It is 90 km (56 mi) northwest of the small community ofTelegraph Creek and just southwest of Callison Ranch. With a maximum elevation of2,012 m (6,601 ft), it rises above the surrounding landscape on theNahlin Plateau, which is part of the westernStikine Plateau. Heart Peaks has been an area ofprospecting since the 1980s with the discovery ofprecious metals.
Situated in a large area of volcanic activity, Heart Peaks consists of a largeshield volcano. It was formed in the past 23 million years by repeated eruptions of lava and rock. However, present day eruptions have not been observed. A number of related volcanoes are adjacent to Heart Peaks and form an extensive volcanic zone over1,000 km (620 mi) long. The knowledge of Heart Peaks is limited, especially its eruptive history.
Heart Peaks is part of theNorthern Cordilleran Volcanic Province, a long volcanic chain extending from just north of the city ofPrince Rupert in British Columbia throughYukon to theAlaska border. Along this line, theNorth American Plate has been rupturing.[4] Earth'slithosphere consists of several largetectonic plates, which slowly move towards and away from one another, eitherconverging andsubducting ordiverging andrifting;volcanoes andearthquakes are generated by these activities.[5] The west coast ofNorth America is the site of plate margins between the largePacific and North American plates, and also between the smallerJuan de Fuca andCocos plates.[6]
Tectonic activity along theNorth Coast of British Columbia andSoutheast Alaska is characterized bytransform movements of theQueen Charlotte Fault, a plate boundary where the Pacific Plate skids by the North American Plate.[7] As the Pacific Plate moves northward to theAleutian subduction zone, it generates rifting in the North American continent.[4] Magma rises along cracks created by the rifting, and eventually erupts on the surface to form a volcano.[8][9] This geological process has, over time, created the Northern Cordilleran Volcanic Province, which is the most volcanically active area in Canada.[4] However, most of the volcanoes have not been directly dated or have not been dated in sufficient detail to recognize how active they are, making the prediction of volcanic events difficult andvolcanic hazards uncertain.[2]
The nearly oval-shaped Heart Peaks shield volcano is made ofbasalt andtrachybasalt with a composite thickness up to430 m (1,410 ft);pyroclastic rocks are also present.[3][2] It lies just west of the much largerLevel Mountain shield and southwest of the Kawdy volcanoes.[10] A series of steep-sidedlava domes composed ofporphyriticrhyolite and minortrachyte are situated on the western flank of Heart Peaks and display colours such as light green and pink. Rhyolitic lava domes are also present on its summit.[3] The shield is surrounded bytributaries of theInklin River, which flows northwest into theTaku River.[3][11]
Heart Peaks is at least33 km (21 mi) long and no more than19 km (12 mi) wide at its base. The west and east flanks of the volcano are dissected, giving it a rugged appearance. However, its north flank is rounded and relatively smooth while its south flank is rather pointed. The highest elevation of Heart Peaks is2,012 m (6,601 ft) at a small peak roughly in the middle of its summit plateau while the regional elevation of the Nahlin Plateau is1,000 m (3,300 ft). This indicates that Heart Peaks has atopographic prominence of at least1,012 m (3,320 ft). More than 20 unnamed creeks flow from the volcano, which drain into the nearby Dudidontu andSheslay rivers.[12]
With an area of about275 km2 (106 sq mi) and a volume of less than160 km3 (38 cu mi), Heart Peaks is the third-largest volcano in the Northern Cordilleran Volcanic Province, exceeded by theMount Edziza and Level Mountain shields, which cover more than1,000 km2 (390 sq mi).[2] Heart Peaks is over five times larger than theMount Meager massif in southwestern British Columbia, the largeststratovolcano by volume in theGaribaldi Volcanic Belt.[13]
The area surrounding Heart Peaks is largely undeveloped, with Callison Ranch being the only locality.[12][14] Vegetation at the volcano is present mainly on its flanks as its broad summit consists of a rockyplateau.[12] Because of its remote location, Heart Peaks is accessed by helicopter from the small communities ofAtlin andDease Lake.[15]
Little is known about the eruptive history of Heart Peaks because it has not been studied in detail by scientists.[16] The exact age of Heart Peaks is not known, but its first volcanic phase occurred during theNeogene period (between 23 and 2.5 million years ago).[2] The variety of volcanic deposits at Heart Peaks indicates that it has a history of producing not only fluid and passive basaltic lava flows, but also moresilica-rich trachyte and rhyolitic lavas andexplosive eruptions.[3][17]Phreaticbreccias are found at the volcano, providing evidence thatphreatic eruptions have occurred at least once throughout its eruptive history.[15] Features created bysubglacial eruptions are also present.[2] The latest volcanic phase at Heart Peaks is largelyPleistocene (between 2.5 million and 10,000 years ago) in age and late-stageHolocene (10,000 years ago to present) activity is uncertain.[3] This is partly because it is unknown whether Holocene volcanic rocks exist at the volcano.[16] Nevertheless, the last eruption at Heart Peaks is unknown.[3]
Heart Peaks is one of the four volcanoes in the Northern Cordilleran Volcanic Province suggested to have erupted theFinlay tephras. These are situated throughout northwestern British Columbia and likely extend east into theCanadian Rockies. In the Finlay River and Dease Lake areas, twotephra deposits are situated between sand, silt, mud and gravel. They are bothphonolitic to trachytic in composition and high iniron(II) oxide, indicating that the tephras were possibly erupted from a single volcano. Regional plantmacrofossils immediately overlying the youngest Finlay tephra deposit are8960 ± 80 and9180 ± 80radiocarbon years old. This indicates that the Finlay tephras are Early Holocene in age and were deposited shortly after the regional Fraser Glaciation retreated.[16]
The Finlay tephras are largely composed of elements most similar to those ofHoodoo Mountain, a flat-topped volcano that formed subglacially at least 100,000 years ago.[16][18] Two phonolitic lava flows on its south flank were erupted between 10,000 and 9,000 years ago and remain unglaciated. They have a similar chemistry to the glass composition of the Finlay tephras. However, no tephras or pyroclastic rocks have been found at Hoodoo Mountain that were erupted the same time as these lava flows. Therefore, other possible sources have been proposed. At the Mount Edziza volcanic complex, basalts of probableLate Pleistocene to Early Holocene age have been found, but their exact ages and chemical compositions are not well known. Because Heart Peaks and nearby Level Mountain have been poorly studied and it is unknown if they contain Holocene age volcanic rocks, they are also possible sources for the Finlay tephras.[16]
The nameHeart Mountains was adopted in the BC Gazetteer of 1930 with coordinates placing the massif at58°38′N131°57′W / 58.633°N 131.950°W /58.633; -131.950. Subsequently, it was renamed toHeart Peaks on May 6, 1947 and coordinates improved to58°36′N132°00′W / 58.600°N 132.000°W /58.600; -132.000. The name origins are unknown as they have not been recorded.[1] A number of other mountain features in British Columbia also had their name changed in 1947, such as theRainbow Range, which was originally namedRainbow Mountains.[19] The nameHeart Peaks officially refers to two small peaks situated on top of the shield volcano, located at58°35′56″N131°57′48″W / 58.59889°N 131.96333°W /58.59889; -131.96333.[1] Because the shield volcano consists of a single landmass and the nameHeart Peaks was officially given for two peaks on its summit, it is sometimes known asHeart Peak to avoid confusion.[3][20] Heart Peaks is also known asHP in scientific documents and ongeological maps.[2][21]
The western flank of Heart Peaks has been an area ofmineral exploration since 1980. A series of gold-bearing quartz veins were discovered in 1980 within a zone ofargillic alteration covering an area of more than3 km2 (1.2 sq mi). In 1982, a number of geochemical soil surveys were carried out, as well as insufficient hand trenching andscree and rock sampling. In 1983,very low frequency electromagnetic surveys completed49 km (30 mi) of surveying in the area.Exploration diamond drilling in 1984 resulted in the creation of eight widely spaced drill holes while an undocumented diamond drill program created two holes in 1987. Explorations did not resume until 1996 when the United States Diamond Corporation carried out heavy mineral silt sampling and a test induced polarization survey; two diamond drill holes were also created. All of these mineral explorations took place in the Heart Peaks property, which covers an area of2,867 ha (7,080 acres). It consists of seven mineral claims entirely owned by Colorado Resources Ltd. A north trendinggraben structure5 km (3.1 mi) long and3 km (1.9 mi) wide intersects the property.[15]
Like other volcanoes in the Northern Cordilleran Volcanic Province, Heart Peaks is not monitored closely enough by theGeological Survey of Canada to ascertain how active its magma system is. This is partly because it is located in a remote region and no major eruptions have taken place in Canada in the past few hundred years. As a result, volcano monitoring is less important than dealing with other natural processes, includingtsunamis,earthquakes andlandslides.[22] No recent earthquakes are known to have occurred at Heart Peaks.[23] If it were to erupt there would likely be weeks, months or years of warning signs, such as clusters of minor earthquakes that would likely originate less than15 km (9.3 mi) below the surface. They are generally too small to be felt by people, but the existing network ofseismographs has been established to monitor tectonic earthquakes. However, the seismograph network is too far away to provide a good indication of what is happening under the mountain. It may sense an increase in seismic activity if the volcano becomes very restless, but this may only provide a warning for a significant eruption. It might detect activity only once the volcano has started erupting.[22]
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