Zuidwal volcano
Encyclopedia
The Zuidwal volcano is an extinct volcano
in the Netherlands
at more than 2 km below ground under the Wadden Sea
, between Harlingen
and Vlieland
, just south west of the island Griend
. The volcano was last active during the late Jurassic
, (about 160 - 148 Ma ago) and has since been covered by about 2000 meters of sedimentary rock
, most of it shale
and sandstone
from the Cretaceous
.
was doing test drills in the Wadden Sea, hoping to find a gas field that a seismic survey had indicated. To their surprise they hit volcanic rock
beneath the reservoir rock, which turned out to be an extinct volcano. The gas field went in production in 1988 and is still producing gas
. Another clue indicating the presence of the volcano was the temperature. While the usual temperature at that depth is about a 100 °C (212 °F), they found 130 °C (266 °F).
far away from the volcano. During the Cimmerian Orogeny
, the Cimmerian Plate
collided with Kazakhstania
, sending shock waves through the Eurasian Plate
, resulting in volcanism.
The volcano is covered by layers of sandstone from the early Cretaceous that act as reservoir rock for the gas. The seal rock
consists of shale.
The volcanic rock is magnetic, creating a magnetic anomaly
.
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
at more than 2 km below ground under the Wadden Sea
Wadden Sea
The Wadden Sea is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It is rich in biological diversity...
, between Harlingen
Harlingen
Harlingen may mean:* Harlingen, Netherlands, a municipality and city in the province of Friesland* Harlingen, Texas, a city in the United States* Harlingen, New Jersey, an unincorporated village in Montgomery Township, New Jersey, United States...
and Vlieland
Vlieland
Vlieland is a municipality in the northern Netherlands. The municipality of Vlieland has only one major town: Oost-Vlieland . It is the second-least densely populated municipality in the Netherlands ....
, just south west of the island Griend
Griend
Griend is a small uninhabited Dutch island in the Wadden Sea, lying around 12 kilometres south of Terschelling. It is one of the West Frisian Islands, and belongs to the municipality of Terschelling...
. The volcano was last active during the late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
, (about 160 - 148 Ma ago) and has since been covered by about 2000 meters of sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
, most of it shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
and sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
from the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
.
Discovery
The volcano was discovered in 1970 when the French oil company Elf AquitaineElf Aquitaine
Elf Aquitaine was a French oil company which merged with TotalFina to form TotalFinaElf. The new company changed its name to Total in 2003...
was doing test drills in the Wadden Sea, hoping to find a gas field that a seismic survey had indicated. To their surprise they hit volcanic rock
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
beneath the reservoir rock, which turned out to be an extinct volcano. The gas field went in production in 1988 and is still producing gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
. Another clue indicating the presence of the volcano was the temperature. While the usual temperature at that depth is about a 100 °C (212 °F), they found 130 °C (266 °F).
The Volcano
The volcano has a height of approximately 1 km and was formed about 160 million years ago, during a time of orogenesis on the European continent. The eruptions were short and severe with heavy explosions. This, along with the mineral composition, points to volcanic activity as a result of subductionSubduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
far away from the volcano. During the Cimmerian Orogeny
Cimmerian Orogeny
The Cimmerian Orogeny, is an orogeny that created mountain ranges that now lie in Central Asia. The orogeny is believed to have begun 200 - 150 million years ago , when the Cimmerian plate collided with the southern coast of Kazakhstania and North and South China, closing the ancient Paleo-Tethys...
, the Cimmerian Plate
Cimmerian Plate
The Cimmerian Plate is an ancient tectonic plate that comprises parts of present-day Anatolia, Iran, Afghanistan, Tibet, Indochina and Malaya regions. The Cimmerian Plate was formerly part of the ancient supercontinent of Pangaea. Pangaea was shaped like a vast "C", facing east, and inside of the...
collided with Kazakhstania
Kazakhstania
Kazakhstania, also known as the Kazakhstan Block, is a small continental region in the interior of Asia. It consists of that area north and east of the Aral Sea, south of the Siberian craton and west of the Altai Mountains and Lake Balkhash. Politically, it comprises most of Kazakhstan and has a...
, sending shock waves through the Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
, resulting in volcanism.
The volcano is covered by layers of sandstone from the early Cretaceous that act as reservoir rock for the gas. The seal rock
Seal Rock
Seal Rocks is a rock formation island found offshore at the north end of the Ocean Beach, San Francisco, California. Its name is derived from the population of Steller's sea lions and California sea lions who used to haul out on the rock...
consists of shale.
The volcanic rock is magnetic, creating a magnetic anomaly
Magnetic anomaly
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material...
.
External links
- Zuidwalvulkaan VPRO.nl