My OperaDeepest Hydrothermal Vent
Saturday, July 31, 2010 10:16:48 AM
What. The discovery of the so far deepest known hydrothermal vent was reported a few days ago in an early edition of PNAS (21 July 2010). First a few words about hydrothermal vents.
The diagram shows the principle of a hydrothermal vent. Magmatic processes provide the driving mechanism for hydrothermal circulation through oceanic rocks. Seawater with a starting temperature of around 2°C seeps through the lavas above a magmachamber and are heated to around 400°C. The hot water dissolves minerals in from the surrounding rocks. We now have what is called a hydrothermal fluid. When the hydrothermal fluids exit the chimney and mix with the cold seawater sulfide and sulfate precipitates. Most hydrothermal vents are found at an average depth of about 2,100 meters in areas of seafloor spreading along the Mid-Ocean Ridge System. The vents are formed in fields hundreds of meters wide.
The newly discovered hydrothermal vent was however found at a depth of about 5,000 m (5 km), that is about 800 m deeper than the up till then known deepest high-temperature hydrothermal field.
Where. At spreading ridges tectonic plates separate at rates that range from “very fast” (>20 cm∕year) to “ultraslow” (<2 cm∕year). This deep hydrothermal vent was found in the ca. 110 km long ultraslow Mid-Cayman Rise (near Cayman islands in the Caribbean Sea). Let me show you a couple of maps (from Wikipedia) to illustrate the geographic and plate tectonic settings.
The Cayman Trough is a complex transform fault zone pull apart basin which contains the small Mid-Cayman spreading ridge on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. It is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate.
Let us zoom in on the Mid-Cayman Rise.
The 110 km long, deep (4,500–6,500 m) and ultraslow (<2 cm yr−1) Mid-Cayman spreading ridge is tectonically and geographically isolated from all other components of the global ridge system.
The Gonâve Microplate forms part of the boundary between the North American Plate and the Caribbean Plate. It is bounded to the west by the Cayman spreading center, to the north by the Septentrional-Oriente fault zone and to the south by the Walton fault zone that continues to the east as the Enriquillo-Plantain Garden fault zone (Particularly known from the disastrous earthquake in Haiti in January 2010). The existence of this microplate was first proposed in 1991,This has been confirmed by GPS measurements, which show that the overall displacement between the two main plates is split almost equally between the transform fault zones that bound the Gonâve microplate. The microplate is expected to eventually become accreted to the North American Plate.
Location of the Piccard site with deepest vent: 18.54478,-81.7195
Reference:
German et al.
Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise
Published online before print July 21, 2010
doi: 10.1073/pnas.1009205107
Freely available online through the PNAS open access option.
The diagram shows the principle of a hydrothermal vent. Magmatic processes provide the driving mechanism for hydrothermal circulation through oceanic rocks. Seawater with a starting temperature of around 2°C seeps through the lavas above a magmachamber and are heated to around 400°C. The hot water dissolves minerals in from the surrounding rocks. We now have what is called a hydrothermal fluid. When the hydrothermal fluids exit the chimney and mix with the cold seawater sulfide and sulfate precipitates. Most hydrothermal vents are found at an average depth of about 2,100 meters in areas of seafloor spreading along the Mid-Ocean Ridge System. The vents are formed in fields hundreds of meters wide.The newly discovered hydrothermal vent was however found at a depth of about 5,000 m (5 km), that is about 800 m deeper than the up till then known deepest high-temperature hydrothermal field.
Where. At spreading ridges tectonic plates separate at rates that range from “very fast” (>20 cm∕year) to “ultraslow” (<2 cm∕year). This deep hydrothermal vent was found in the ca. 110 km long ultraslow Mid-Cayman Rise (near Cayman islands in the Caribbean Sea). Let me show you a couple of maps (from Wikipedia) to illustrate the geographic and plate tectonic settings.
The Cayman Trough is a complex transform fault zone pull apart basin which contains the small Mid-Cayman spreading ridge on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. It is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate.
Let us zoom in on the Mid-Cayman Rise.
The 110 km long, deep (4,500–6,500 m) and ultraslow (<2 cm yr−1) Mid-Cayman spreading ridge is tectonically and geographically isolated from all other components of the global ridge system.
The Gonâve Microplate forms part of the boundary between the North American Plate and the Caribbean Plate. It is bounded to the west by the Cayman spreading center, to the north by the Septentrional-Oriente fault zone and to the south by the Walton fault zone that continues to the east as the Enriquillo-Plantain Garden fault zone (Particularly known from the disastrous earthquake in Haiti in January 2010). The existence of this microplate was first proposed in 1991,This has been confirmed by GPS measurements, which show that the overall displacement between the two main plates is split almost equally between the transform fault zones that bound the Gonâve microplate. The microplate is expected to eventually become accreted to the North American Plate.
Location of the Piccard site with deepest vent: 18.54478,-81.7195
Reference:
German et al.
Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise
Published online before print July 21, 2010
doi: 10.1073/pnas.1009205107
Freely available online through the PNAS open access option.
- http://earthobservatory.nasa.gov/Newsroom/view.php?id=44788&src=eorss-nnews
- http://www.whoi.edu/page.do?pid=7545&tid=282&cid=78266&ct=162
- http://blogs.discovermagazine.com/80beats/2010/07/21/16000-feet-under-the-sea-deepest-hydrothermal-vent-discovered/
- http://www.pnas.org/content/early/2010/07/13/1009205107.abstract
- http://www.eurekalert.org/pub_releases/2010-07/whoi-etm072010.php
- http://www.whoi.edu/page.do?pid=35435
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