Tectonic fabric of the Atlantic and Indian oceans and continental drift

The floor of the Indian Ocean is dominated by (1) the seismically active Mid-Oceanic Ridge, (2) scattered linear micro-continents (mostly meridional), and (3) fracture zones (some displace the axis of the Mid-Oceanic Ridge and others parallel the micro-continents). The pattern suggests that movement along the Diamantina Fracture Zone has displaced Australia to the east relative to Broken Ridge. In the Arabian Sea north-northeast trending fracture zones have displaced the axis of the Carlsberg Ridge. The complex tectonic fabric of the Indian Ocean is difficult to explain in terms of a simple pattern of convection currents. The location and origin of the Mid-Oceanic Ridge, of oceanic rises, aseismic ridges and transcurrent fault systems must be accounted for in any hypothesis of continental displacement despite unique or exotic assumptions as to strength, viscosity or composition of the oceanic crust and mantle.

As a result of the International Indian Ocean Expedition, the bottom of the Indian Ocean is now one of the best known areas of the ocean floor. The Mid-Indian Ocean Ridge, a rugged mountain range, lies in the centre of the Indian Ocean. North-northeast trending fractures offset the axis of the ridge. In the Arabian Sea these fractures are right lateral; in the southwest Indian Ocean they are left lateral. Displacements range from a few miles* to over 200 miles. The northeast Arabian Sea and the Bay of Bengal are occupied by huge abyssal cones built by sediments discharged from the Indo-Gangetic plain. Extensive abyssal plains lie seaward of the abyssal cones. In low latitudes smooth topography is characteristic of the continental rise, the abyssal cones, and the oceanic rises. However, near the polar front smooth c swale9 topography laps over the normally rugged Mid-Oceanic Ridge. This c swale5 smoothing appears the result of the higher organic productivity of the Antarctic seas. Microcontinents, mostly linear meridional ridges, are unique features of the Indian Ocean. These massive but smooth-surfaced blocks contrast markedly with the broad rugged Mid-Oceanic Ridge.


1998 ◽  
Vol 41 (2) ◽  
Author(s):  
R. Hantke ◽  
A. E. Scheidegger

A study is made of the orientations (strikes/trends) of joints, valleys, ridges and lineaments, i.e. of the (potentially) morphotectonic features, of the Mascarene Islands (Reunion, Mauritius and Rodrigues) in the Indian Ocean. It turns out that a connection exists between these features on all islands. For the joints alone, the results for Mauritius as a whole agree closely with those for Rodrigues as a whole, and also partially with those of Reunion. Inasmuch as the trends of the valleys, ridges and lineaments are related to the trends (strikes) of the joints, a common morphotectonic predesign seems to be present for all features studied. The morphotectonic orientations on the island also agree closely with the trends of fracture zones, ridges and trenches in the nearby ocean bottom; which has had a bearing on the theories of the origin of the Mascarene Islands. Generally, a hot-spot origin is preferred for Reunion, and may be for Mauritius as well, although differing opinions have also been voiced. The dynamics of a hot-spot is hard to reconcile with the close fit of the joint strikes in Réunion with the trends of the Madagascar and Rodrigues fracture zones. The closely agreeing joint maxima in Mauritius and Rodrigues í across the deep Mauritius trench í also agree with the trend of that trench and with the trend of the Rodrigues fracture zone. Thus, it would appear as most likely that the trends of joints and of fracture zones are all part of the same pattern and are due to the same cause: viz. to action of the neotectonic stress field.


Author(s):  
E. P. Dubinin ◽  
A. V. Kokhan ◽  
G. L. Leitchenkov ◽  
A. A. Shaikhullina

The article is dedicated to review of structural and evolutionary peculiarities of the southern part of central sector of the Indian ocean. Study is based on analyses of global digital models, distribution of fractures, global and regional lithosphere evolution models and published geological and geophysical data. As a result of study, tectonic regionalization of oceanic crust of the area is presented and main evolution stages of the region are distinguished.


Check List ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 1544 ◽  
Author(s):  
Amruta Prasade ◽  
Deepak Apte ◽  
Purushottam Kale ◽  
Otto M.P. Oliveira

The benthic ctenophore Vallicula multiformis Rankin, 1956 is recorded for the first time in the Arabian Sea, from the Gulf of Kutch, west coast of India in March 2013. This occurrence represents a remarkable extension of its geographic distribution that until now included only known the Pacific and Atlantic oceans.


2001 ◽  
Vol 7 (S2) ◽  
pp. 480-481
Author(s):  
James R. Anderson ◽  
Peter Crozier

The Indian Ocean Experiment (INDOEX) was conducted in Feb.-Mar. 1999 in a large area of the Indian Ocean, Bay of Bengal, and Arabian Sea to investigate climate forcing produced by pollutant aerosol particles being transported out of India, Pakistan, and Indochina during the Northeast (“Dry“) Monsoon2. Pollutant aerosols can be transported a thousand km or more by prevailing winds as far south as the Inter-tropical Convergence Zone (ITCZ), the convective band that separates Northern and Southern Hemisphere tropospheric air. We present here results from TEM examination of aerosol particles collected on INDOEX research flights of the NCAR C-130 aircraft.The climate forcing properties of sulfate aerosols over the oceans have long been recognized2. Sulfate and other particles scatter incoming solar radiation, reducing the amount of light (and heat) incident on the ocean surface and thus causing a cooling effect which may locally counter some of the warming effect due to greenhouse gases.


2003 ◽  
Vol 107 (3) ◽  
pp. 683-695 ◽  
Author(s):  
D. Bala Subrahamanyam ◽  
Radhika Ramachandran ◽  
K. Sen Gupta ◽  
Tuhin K. Mandal

2004 ◽  
Vol 22 (8) ◽  
pp. 2679-2691 ◽  
Author(s):  
M. V. Ramana ◽  
P. Krishnan ◽  
S. Muraleedharan Nair ◽  
P. K. Kunhikrishnan

Abstract. Spatial and temporal variability of the Marine Atmospheric Boundary Layer (MABL) height for the Indian Ocean Experiment (INDOEX) study period are examined using the data collected through Cross-chained LORAN (Long-Range Aid to Navigation) Atmospheric Sounding System (CLASS) launchings during the Northern Hemispheric winter monsoon period. This paper reports the results of the analyses of the data collected during the pre-INDOEX (1997) and the INDOEX-First Field Phase (FFP; 1998) in the latitude range 14°N to 20°S over the Arabian Sea and the Indian Ocean. Mixed layer heights are derived from thermodynamic profiles and they indicated the variability of heights ranging from 400m to 1100m during daytime depending upon the location. Mixed layer heights over the Indian Ocean are slightly higher during the INDOEX-FFP than the pre-INDOEX due to anomalous conditions prevailing during the INDOEX-FFP. The trade wind inversion height varied from 2.3km to 4.5km during the pre-INDOEX and from 0.4km to 2.5km during the INDOEX-FFP. Elevated plumes of polluted air (lofted aerosol plumes) above the marine boundary layer are observed from thermodynamic profiles of the lower troposphere during the INDOEX-FFP. These elevated plumes are examined using 5-day back trajectory analysis and show that one group of air mass travelled a long way from Saudi Arabia and Iran/Iraq through India before reaching the location of measurement, while the other air mass originates from India and the Bay of Bengal.


1975 ◽  
Vol 28 (4) ◽  
pp. 434-448
Author(s):  
H. Grosset-Grange

This study of fifteenth-century Arab sailing directions for the Indian Ocean is translated from a paper which was published in the July 1974 issue of Navigation, the Journal of the French Institute of Navigation. The spelling of modern place names has been assimilated to that of the Admiralty Charts and Sailing Directions but other Arabic names and terms have been left in the authors' approximate transliteration. Quotations from the Arabic texts are printed in italics.


2015 ◽  
Vol 8 ◽  
Author(s):  
Anil Mohapatra ◽  
Dipanjan Ray ◽  
David G. Smith

Gymnothorax prolatusis recorded for the first time from the Indian Ocean on the basis of four specimens collected in the Bay of Bengal off India and one from the Arabian Sea off Pakistan. These records extend the range of the species from Taiwan to the north-western Indian Ocean.


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