| Franklin Glacier Complex | |
|---|---|
 Satellite image of the Franklin Glacier Complex | |
| Highest point | |
| Elevation | 2,000+ m (6,600+ ft) |
| Dimensions | |
| Length | 20 km (12 mi) |
| Width | 6 km (3.7 mi) |
| Area | 130 km2 (50 sq mi) |
| Geography | |
 | |
| Country | Canada |
| Province | British Columbia |
| District | Range 2 Coast Land District |
| Parent range | Waddington Range |
| Topo map | NTS 92N6Mount Waddington |
| Geology | |
| Rock age | Miocene-to-Pleistocene[2] |
| Mountain type | Eroded volcano[1] |
| Volcanic arc | Canadian Cascade Arc |
| Volcanic belt | Pemberton/Garibaldi Belt |
TheFranklin Glacier Complex is a deeply eroded volcano in theWaddington Range of southwesternBritish Columbia, Canada. Located about65 km (40 mi) northeast ofKingcome, this little-known complex is adjacent toFranklin Glacier nearMount Waddington. It is over2,000 m (6,600 ft) in elevation and due to its considerable overall altitude, a large proportion of the complex is covered by glacial ice.
Magmatic activity of the Franklin Glacier Complex spanned roughly four million years from theLate Miocene to theEarly Pleistocene, with the most recently identified volcanic eruption having taken place around 2.2 million years ago. The existence of thermal springs near the complex implies that magmatic heat is still present. It has therefore been of interest togeothermal exploration.
The area lies in one of British Columbia's many territorial divisions called the Range 2 Coast Land District.[3] Local relief exceeds2,000 m (6,600 ft) with the18 km (11 mi) long valley-filling Franklin Glacier originating from anicefield below the west face of Mount Waddington.[2][4] It is part of the Waddington Range, a subrange of thePacific Ranges which in turn are a subdivision of theCoast Mountains.[4][5]
The Franklin Glacier Complex was covered by theCordilleran Ice Sheet until itsretreat about 13,000 years ago. Franklin Glacier has since undergone glacial retreat and expansion throughout theHolocene. It appears to have retreated significantly during the early Holocene warm period, followed by advancements 6,300, 5,400, 4,600, 4,100, 3,100, 2,400, 1,500, 800 and 600 years ago. The timing of expansions corresponded with cool summer temperatures, generally moist conditions and increased precipitation.[4]
Minimal geologic studies have been conducted at the Franklin Glacier Complex and itsgeology is therefore poorly known.[1] It measures6 km (3.7 mi) wide and20 km (12 mi) long, covering a northwesterly elliptical area of130 km2 (50 sq mi).[2][6]Volcanic rocks of the Franklin Glacier Complex consist predominantly ofdacitebreccia, minor dacite flows and a fewhornblendeandesite remnants. An absence ofpumice,glassyblocks orbombs in the breccia suggests that it may be of epiclastic origin, possibly formed during collapse and infilling of acaldera.[2] The complex has therefore been described as a caldera or a cauldron subsidence.[7][8] Heavy erosion of the volcanic rocks has exposed a series ofbiotite-quartz-porphyry, biotite quartz-feldspar-porphyry andquartz monzonite subvolcanicplutons anddike swarms. They intrude through fractured andhydrothermally alteredMesozoic to earlyTertiarygranitic andmetamorphic rocks of the Coast Plutonic Complex.[2]
The complex lies on the overlapping trend of theGaribaldi andPembertonvolcanic belts, which were formed as a result ofsubduction zonemagmatism along theCascade Volcanic Arc in the last 29 million years.[1][9][10] Two separate stages of magmatic activity have been identified at the Franklin Glacier Complex.[2] The first magmatic stage about 6.8 million years ago involved the central emplacement of an elongated quartz monzonitestock.[2][11] At least five porphyry and transitionalvein-type mineral occurrences were deposited during this period.[11] A series of smallerintrusions were emplaced during the second magmatic stage 2.2 to 3.9 million years ago, at least some of which appear to have been feeders for the overlying volcanic pile.[2] The Franklin Glacier Complex is substantially older than the neighbouringSilverthrone Caldera to the northwest.[1]
Immediately west of the Franklin Glacier Complex are a series ofhot springs confined in valleys. At Canyon Lake, a hot spring feeds a small stream that flows into the southeastern end of that lake. A single temperature of58 °C (136 °F) has been obtained from this spring while the Hoodoo Creek and Pinter spring temperatures remain unknown. The existence of these hot springs has made the Franklin Glacier Complex a target for geothermal exploration but little work has been conducted due to its remote location. The only performed exploration has been moderategeological mapping. A 50 megawattbinary plant has been proposed at Canyon Lake.[12]
Mineral exploration at the Franklin Glacier Complex has occurred sporadically since at least the 1960s. The earliest recorded work was done by Kennco Exploration Limited with the staking of claims in a zone ofcopper-molybdenummineralization associated with the quartz monzonite stock. This was followed by geological mapping, silt and soilgeochemical sampling and192 m (630 ft) ofdiamond drilling in seven shortboreholes. Kennco conducted no further work which led to the eventual lapse of their mineral claims in 1976. The area was restaked later that year by United Mineral Services Limited who would conduct reconnaissance mapping and regional research. In 1987–1988, United Pacific Gold Limited performed trenching, mapping,geophysics, geochemical sampling and785 m (2,575 ft) of diamond drilling in nine boreholes. Mineral claims were staked once again in 1996 by F. Onucki and J. R. Deighton for the purpose of locating reported high-gradesilver mineralization.[11]
Franklin Glacier was skied by CanadianmountaineersDon andPhyllis Munday on July 22, 1930 while exploring and mapping glaciers of the Waddington Range.[5] Don Munday named the glacier in 1927 for its association with the Franklin River which in turn was named after a Benjamin Franklin atTatla Lake.[3][13]