Linking collision, slab break-off and subduction polarity reversal in the evolution of the Central Indian Tectonic Zone

2020 ◽  
Vol 157 (2) ◽  
pp. 340-350
Author(s):  
Tanzil Deshmukh ◽  
N. Prabhakar
Keyword(s):  
Polarity Reversal ◽  
The South ◽  
Tectonic Zone ◽  
The North ◽  
Tectonic Processes ◽  
South Indian ◽  
Indian Craton ◽  
Directed System ◽  
Central Indian Tectonic Zone ◽  
Collisional Regime

AbstractThe Central Indian Tectonic Zone demarcates the zone of amalgamation between the North Indian Craton and the South Indian Craton. Presently, the major controversies in the existing tectonic models of the Central Indian Tectonic Zone revolve around the direction of subduction and the precise timing of accretion between the North Indian Craton and the South Indian Craton. A new model for the tectonic evolution of the Central Indian Tectonic Zone is postulated in this contribution, based on recent geological and geophysical evidence, combined with previously documented tectonic configurations. The present study employs the slab break-off hypothesis and subsequent polarity reversal to explain the tectonic processes involved in the evolution of the Central Indian Tectonic Zone. We propose that the subduction initiated (c. 2.5 Ga) in a S-directed system producing island-arc sequences on the South Indian Craton. The southward subduction regime culminated with slab break-off underneath the South Indian Craton between c. 1.65 Ga and 1.55 Ga, which subsequently induced subduction polarity reversal and set the course for N-directed subduction (<1.55 Ga). The final closure along the Central Indian Tectonic Zone is governed by the collisional regime during the Sausar Orogeny (1.0–0.9 Ga).

scholarly journals Tectonic reconstruction of Uda-Murgal arc and the Late Jurassic and Early Cretaceous convergent margin of Northeast Asia–Northwest Pacific

2009 ◽  
Vol 4 ◽  
pp. 273-288 ◽  
Author(s):  
S. D. Sokolov ◽  
G. Ye. Bondarenko ◽  
A. K. Khudoley ◽  
O. L. Morozov ◽  
M. V. Luchitskaya ◽  
...  
Keyword(s):  
Northeast Asia ◽  
Upper Jurassic ◽  
Island Arc ◽  
Passive Margin ◽  
Northwest Pacific ◽  
Island Arcs ◽  
The South ◽  
Convergent Margin ◽  
Tectonic Zone ◽  
The North

Abstract. A long tectonic zone composed of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks is recognized along the Asian continent margin from the Mongol-Okhotsk fold and thrust belt on the south to the Chukotka Peninsula on the north. This belt represents the Uda-Murgal arc, which was developed along the convergent margin between Northeast Asia and Northwest Meso-Pacific. Several segments are identified in this arc based upon the volcanic and sedimentary rock assemblages, their respective compositions and basement structures. The southern and central parts of the Uda-Murgal arc were a continental margin belt with heterogeneous basement represented by metamorphic rocks of the Siberian craton, the Verkhoyansk terrigenous complex of Siberian passive margin and the Koni-Taigonos Late Paleozoic to Early Mesozoic island arc with accreted oceanic terranes. At the present day latitude of the Pekulney and Chukotka segments there was an ensimatic island arc with relicts of the South Anyui oceanic basin in a backarc basin. Accretionary prisms of the Uda-Murgal arc and accreted terranes contain fragments of Permian, Triassic to Jurassic and Jurassic to Cretaceous (Tithonian–Valanginian) oceanic crust and Jurassic ensimatic island arcs. Paleomagnetic and faunal data show significant displacement of these oceanic complexes and the terranes of the Taigonos Peninsula were originally parts of the Izanagi oceanic plate.

Trend Analysis with a New Global Record of Tropical Cyclone Intensity

2013 ◽  
Vol 26 (24) ◽  
pp. 9960-9976 ◽  
Author(s):  
James P. Kossin ◽  
Timothy L. Olander ◽  
Kenneth R. Knapp
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Satellite Data ◽  
Formal Analysis ◽  
P Value ◽  
Tropical Cyclone Intensity ◽  
The South ◽  
Cyclone Intensity ◽  
The North ◽  
South Indian

Abstract The historical global “best track” records of tropical cyclones extend back to the mid-nineteenth century in some regions, but formal analysis of these records is encumbered by temporal heterogeneities in the data. This is particularly problematic when attempting to detect trends in tropical cyclone metrics that may be attributable to climate change. Here the authors apply a state-of-the-art automated algorithm to a globally homogenized satellite data record to create a more temporally consistent record of tropical cyclone intensity within the period 1982–2009, and utilize this record to investigate the robustness of trends found in the best-track data. In particular, the lifetime maximum intensity (LMI) achieved by each reported storm is calculated and the frequency distribution of LMI is tested for changes over this period. To address the unique issues in regions around the Indian Ocean, which result from a discontinuity introduced into the satellite data in 1998, a direct homogenization procedure is applied in which post-1998 data are degraded to pre-1998 standards. This additional homogenization step is found to measurably reduce LMI trends, but the global trends in the LMI of the strongest storms remain positive, with amplitudes of around +1 m s−1 decade−1 and p value = 0.1. Regional trends, in m s−1 decade−1, vary from −2 (p = 0.03) in the western North Pacific, +1.7 (p = 0.06) in the south Indian Ocean, +2.5 (p = 0.09) in the South Pacific, to +8 (p &lt; 0.001) in the North Atlantic.

The South Indian Tradition of the Apostle Thomas

1924 ◽  
Vol 56 (S1) ◽  
pp. 213-223 ◽  
Author(s):  
P. J. Thoma
Keyword(s):  
South India ◽  
Sixth Century ◽  
The South ◽  
The North ◽  
Indian Tradition ◽  
South Indian ◽  
Christian Origins ◽  
Final Settlement

Although a great deal has been written concerning St. Thomas's connexion with India, it has so far resulted only in barren controversies and inchoate theories. The finding of the “Gondophares.” coins in the Cabul region raised great hopes of a final settlement of the problem; but apart from the (itself doubtful) identification of a single name in the Ada Thomae, it has shed little light on the mysteries of Christian origins in India. Nay, it has had positively injurious results, inasmuch as it diverted the attention of scholars into fields far remote from the familiar haunts of the Thomistic tradition. South India is the quarter from which we should expect fresh evidence: the north has no known claims to any connexion with the Apostle. In the south live the Christians of St. Thomas—the so-called “Syrians” who for more than a thousand years have upheld their descent from the Apostle's disciples. There also we have what has been believed from immemorial antiquity to be the tomb of St. Thomas, with various lithic remains of pre-Portuguese Christianity around Madras. South India has a remarkably ancient tradition of St. Thomas; and it is a living tradition, not a dead legend. It can be traced back at least to the sixth century a.d., and it still lives in popular memories, not only of Christians, but of others not recognizing the claims of Christianity. The existence of this tradition is known and recognized; but no organized attempt has yet been made to explore it.

scholarly journals Southern Chile crustal structure from teleseismic receiver functions: Responses to ridge subduction and terrane assembly of Patagonia

Geosphere ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 378-391 ◽  
Author(s):  
E.E. Rodriguez ◽  
R.M. Russo
Keyword(s):  
Crustal Structure ◽  
Triple Junction ◽  
Oceanic Lithosphere ◽  
Receiver Functions ◽  
Moho Depth ◽  
The South ◽  
Ridge Subduction ◽  
The North ◽  
Tectonic Processes ◽  
Chile Triple Junction

Abstract Continental crustal structure is the product of those processes that operate typically during a long tectonic history. For the Patagonia composite terrane, these tectonic processes include its early Paleozoic accretion to the South America portion of Gondwana, Triassic rifting of Gondwana, and overriding of Pacific Basin oceanic lithosphere since the Mesozoic. To assess the crustal structure and glean insight into how these tectonic processes affected Patagonia, we combined data from two temporary seismic networks situated inboard of the Chile triple junction, with a combined total of 80 broadband seismic stations. Events suitable for analysis yielded 995 teleseismic receiver functions. We estimated crustal thicknesses using two methods, the H-k stacking method and common conversion point stacking. Crustal thicknesses vary between 30 and 55 km. The South American Moho lies at 28–35 km depth in forearc regions that have experienced ridge subduction, in contrast to crustal thicknesses ranging from 34 to 55 km beneath regions north of the Chile triple junction. Inboard, the prevailing Moho depth of ∼35 km shallows to ∼30 km along an E-W trend between 46.5°S and 47°S; we relate this structure to Paleozoic thrust emplacement of the Proterozoic Deseado Massif terrane above the thicker crust of the North Patagonian/Somún Cura terrane along a major south-dipping fault.

scholarly journals Some of the Wild Life Problems of Ceylon

Oryx ◽  
1959 ◽  
Vol 5 (3) ◽  
pp. 125-137
Author(s):  
R. M. Bere
Keyword(s):  
The South ◽  
Indian Peninsula ◽  
Climatic Regions ◽  
North East ◽  
The North ◽  
South Indian ◽  
Life Problems ◽  
Dry Zone ◽  
Wild Life ◽  
Wet Zone

Topographically Ceylon is a detached portion of the South Indian peninsula. It divides into two climatic regions, known as the Dry and Wet Zones; the latter occupies approximately the south-western quarter of the island. By African standards, dry and wet are relative terms and there may be over 80 inches of rain in the Dry Zone. Even so, rainfall tends to be concentrated and long periods without rain occur. The Wet Zone receives rain during both monsoons, the Dry Zone during the north-east monsoon only. Monsoons sometimes fail and serious droughts are not uncommon.

3,360-Myr old gneisses from the South Indian Craton

Nature ◽  
1980 ◽  
Vol 283 (5746) ◽  
pp. 469-470 ◽  
Author(s):  
R. D. Beckinsale ◽  
S. A. Drury ◽  
R. W. Holt
Keyword(s):  
The South ◽  
South Indian ◽  
Indian Craton

The phosphate levels of the major surface currents of the Indian Ocean

1967 ◽  
Vol 18 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Indian Ocean ◽  
High Salinity ◽  
Average Rate ◽  
North Indian Ocean ◽  
Surface Currents ◽  
The South ◽  
South Indian Ocean ◽  
The North ◽  
South Indian ◽  
South West Monsoon

The principal surface currents of the north Indian Ocean are much richer in phosphate (greater than 0.25 �g-atom/l) than those of the south Indian Ocean (less than 0.15 �g-atom/I). In summer large areas of the surface waters of the south-east Indian Ocean have a very low phosphate content (less than 0.10 �g-atom/l). These waters are by far the lowest in phosphate of the whole Indian Ocean. Their salinity-temperature- phosphate relations show that waters from two regions, the South Equatorial Current in the north and the high salinity belt around 30-35� S., contribute to their formation. Waters of this high salinity belt are carried northward into the low phosphate region by the West Australian Current in summer. These high-salinity waters most probably form by evaporation of an upper 50-m mixed layer of waters of the south-east Atlantic drifting eastward in the south Indian Ocean at an average rate of 15 cm per sec. In the eastern Indian Ocean north of 10�S., surface phosphate levels in summer are governed by the circulation of the richer phosphate waters of the counter current. In winter the circulation of richer phosphate waters of the South-west Monsoon Current governs the phosphate level.

Source regions of oxygen maxima in intermediate depths of the Arabian Sea.

1966 ◽  
Vol 17 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Indian Ocean ◽  
Arabian Sea ◽  
Structural Features ◽  
The South ◽  
The North ◽  
Source Regions ◽  
South Indian ◽  
Indian Central ◽  
South West Monsoon ◽  
The Indian Ocean

Oxygen maxima, in relation to σt salinity maxima and minima, and other hydrological structural features, have been examined along three meridional sections of the Indian Ocean. These relations have provided a background for the interpretation of the water mass sources of oxygen maxima of the whole Indian Ocean. After grouping these oxygen maxima according to density, their salinities have been used to identify mixing circuits in which the following waters are involved: from the south (1) South Indian Central, (2) Subtropical oxygen maximum, (3) Antarctic Intermediate; from the east (4) Equatorial Frontal water; and from the north (5) Persian Gulf, and (6) Red Sea. The principal routes whereby oxygen-rich mixtures of these waters enter the Arabian Sea, during the south-west monsoon, have been determined. The directions of flow along several of these routes agreed with measured directions of current flow. Where these currents disagreed the measured current was generally very weak.

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