Broken Ridge

from Wikipedia, the free encyclopedia
Broken Ridge Plateau
Photo-request.svg
Image wanted BW
height 1000 m below sea level
location southwest of Australia
Coordinates 31 ° 0 ′ 0 ″  S , 95 ° 0 ′ 0 ″  E Coordinates: 31 ° 0 ′ 0 ″  S , 95 ° 0 ′ 0 ″  E
Broken Ridge (Indian Ocean)
Broken Ridge
Type Deep sea mountain

f

Map of the Southeast Indian Ridge. Broken Ridge is the green area in the upper left corner.

As Broken Ridge and Broken Plateau is called an oceanic plateau in the southeastern Indian Ocean . The Broken Ridge used to form together with the Kerguelen Plateau an igneous large province (Large Igneous Province, LIP). When the Australian and Antarctic plates separated, the Broken Ridge and Kerguelen Plateau were also separated by the Southeast Indian Ridge . Broken Ridge's alkaline basalt has been determined to be 95 million years old.

The Broken Ridge extends 1200 km from the south end of the Ninety Degree East Ridge towards the south west corner of Australia . It reaches a width of 400 km and rises to 1000 m below sea level. On its south side follows the Diamantina Escarpment, a 3000 m wide stratification , while the plateau on the north side slopes gently to the sea depth of the Wharton Basin . To the southeast is the Diamantina Fracture Zone . The sediment layers on the plateau reach a thickness of 800 m and the Mohorovičić discontinuity is about 20 km deep. The ridge is separated from the Naturaliste Plateau by the Dirck Hartog Ridge .

The Kerguelen Greater Province originally covered 2.3 million km², making it the second largest LIP on earth (after the Ontong Java Plateau in the Pacific ). Both of these enormous LIPs reached heights of 2-4 km above the surrounding ocean floor and a crustal thickness of 20-40 km. In comparison, the oceanic crust is typically 7 km thick. The Broken Ridge and the Kerguelen Plateau are now 1,800 km apart. As they drifted apart, the southern flank of Broken Ridge was raised 2,000 m and rose to above sea level.

The Kerguelen LIP has a long and complicated history and is probably the least "typical" of all LIPs. Rocks from both plateaus, both the Broken Ridge and the Kerguelen Plateau, have a common “continental component”, a recognizable composition. In the early Cretaceous period , the Kerguelen hotspot was divided into several diapirs of different sizes, compositions, and rates of ascent. These separate diapirs created the Bunbury - Basalt , southern Kerguelen Plateau, the Rajmahal Traps or Indian lamprophyre , the Antarctic lamprophyre and the central Kerguelen Plateau and Broken Ridge. In the Late Cretaceous, activity on the Earth's mantle slowed and the Kerguelen hotspot shrank to a single spot on the ninety-degree east ridge. 120–95 million years ago, when the southern and central Kerguelen Plateau formed along with the Broken Ridge, the Kerguelen hotspot formed about 1 km³ per year, but in the period 95–25 million years ago the output decreased to 0.1 km³ per year.

Individual evidence

  1. ↑ a b Schlich 2013: 79-80.
  2. ↑ a b Frey, Coffin, Wallace, Weis: Mantle sources, plume-lithosphere interactions, and plume models. 2003: 15-17.
  3. ↑ a b Ingle 2007.
  4. ↑ a b Frey, Coffin, Wallace, Weis: Introduction 2000: 74-77.
  5. ↑ Frey, Coffin, Wallace, Weis 2003: 18

swell

  • FA Frey, MF Coffin, PJ Wallace, D. Weis, Zhao X., SW Wise Jr., V. Wähnert, DAH Teagle, PJ Saccocia, DN Reusch, MS Pringle, KE Nicolaysen, CR Neal, RD Müller, CL Moore, JJ Mahoney, L. Keszthelyi, H. Inokuchi, RA Duncan, H. Delius, JE Damuth, D. Damasceno, HK Coxall, MK Borre, F. Boehm, J. Barling, NT Arndt, M. Antretter: Origin and evolution of a submarine large igneous province: the Kerguelen Plateau and Broken Ridge, southern Indian Ocean. In: Earth and Planetary Science Letters 2000, vol. 175, 1: 73-89. PDF August 30, 2015. (doi 10.1016 / S0012-821X (99) 00315-5)
  • FA Frey, MF Coffin, PJ Wallace, D. Weis: Leg 183 Summary: Kerguelen Plateau-Broken Ridge — A Large Igneous Province. In: FA Frey, MF Coffin, PJ Wallace, PG Quilty: Proceedings of the Ocean Drilling Program. 2003 vol. 183: 1-48. PDF August 30, 2015.
  • S. Ingle: April 2007 LIP of the Month: The Kerguelen Large Igneous Province. Large Igneous Provinces Commission 2007. largeigneousprovinces.org September 27, 2015.
  • R. Schlich: The Indian Ocean: Aseismic Ridges, Spreading Centers, and Oceanic Basins. In: AEM Nairn: The Ocean Basins and Margins: The Indian Ocean. Springer 2013: 51-84. Google books September 27, 2015. ISBN 978-1-4615-8038-6