The Geological Framework

2005 ◽  
Author(s):  
Charles S. Hutchison
Keyword(s):  
Indian Ocean ◽  
Southeast Asia ◽  
Deep Water ◽  
Plate Tectonics ◽  
Petroleum Industry ◽  
South Indian ◽  
Lithospheric Plates ◽  
Asean Countries ◽  
Convergent Plate Margin ◽  
Straits Of Malacca

This chapter outlines the principal geological features of the region, extending from Myanmar and Taiwan in the north, southwards to include all the ASEAN countries, and extending as far as northern Australia. The present-day lithospheric plates and plate margins are described, and the Cenozoic evolution of the region discussed. Within a general framework of convergent plate tectonics, Southeast Asia is also characterized by important extensional tectonics, resulting in the world’s greatest concentration of deep-water marginal basins and Cenozoic sedimentary basins, which have become the focus of the petroleum industry. The pre-Cenozoic geology is too complex for an adequate analysis in this chapter and the reader is referred to Hutchison (1989) for further details. A chronological account summarizing the major geological changes in Southeast Asia is given in Figure 1.2. The main geographical features of the region were established in the Triassic, when the large lithospheric plate of Sinoburmalaya (also known as Sibumasu), which had earlier rifted from the Australian part of Gondwanaland, and collided with and became sutured onto South China and Indochina, together named Cathaysia. The result was a great mountain-building event known as the Indosinian orogeny. Major granites were emplaced during this orogeny, with which the tin and tungsten mineral deposits were genetically related. The orogeny resulted in general uplift and the formation of major new landmasses, which have predominantly persisted as the present-day regional physical geography of Southeast Asia. The Indo-Australian Plate is converging at an average rate of 70 mm a−1 in a 003° direction, pushed from the active South Indian Ocean spreading axis. For the most part it is composed of the Indian Ocean, formed of oceanic sea-floor basalt overlain by deep water. It forms a convergent plate margin with the continental Eurasian Plate, beneath which it subducts at the Sunda or Java Trench. The Eurasian continental plate protrudes as a peninsular extension (Sundaland) southwards as far as Singapore, continuing beneath the shallow Straits of Malacca and the Sunda Shelf as the island of Sumatra and the northwestern part of Borneo.

The Acheh Treaty of 1819

1961 ◽  
Vol 2 (3) ◽  
pp. 36-46
Author(s):  
T. Puvanarajah ◽  
R. Suntharalingam
Keyword(s):  
Indian Ocean ◽  
Southeast Asia ◽  
Bay Of Bengal ◽  
Napoleonic Wars ◽  
Early 19Th Century ◽  
North East ◽  
The North ◽  
British Policy ◽  
The Indian Ocean ◽  
Straits Of Malacca

The strategic location of Acheh at the northern entrance of the Straits of Malacca coupled with the Sultanate's control of the pepper districts of north Sumatra were vital factors affecting British policy towards Acheh in the late 18th and early 19th century. During this period, Britain was involved in a series of wars with France in Europe, and these wars came to affect Anglo-French relations in the Indian Ocean. British possessions in India, especially those situated in the Bay of Bengal, were vulnerable to French naval attacks during the period of the north-east monsoons. The danger of French attack was first felt during the Seven Years War (1756–1763) and after peace was signed in 1763 the Directors of the Company recommended the search for a base to the east of the Bay of Bengal. The result of this protracted search was the foundation of Penang in 1786. But settlement at Penang did not entirely remove the fears of the British vis a vis the French naval threat to their Indian possessions. There were, in Southeast Asia, other stations which the French could use “with complete impunity” to launch an attack on the Company's settlements in the Bay of Bengal. Acheh was one base which seemed to fit into French strategy. During the War of American Independence, de Suffren, the brilliant French naval commander, had utilised Acheh as a refit and supply station, after having launched an attack on British territories in India. In 1796, another French commander, Sercey also refitted his fleet at Acheh. The outbreak of Napoleonic Wars in Europe, and the fear of renewed French actions in the Bay induced the Directors to sanction the building of a naval base in Penang in 1805. In their instructions to the newly created Penang Presidency, the Directors drew its attention to the existence of “an inviting port opened to him [European enemy] in Acheen” which the French could use. In an attempt to counter any French designs, the Directors were prepared to sanction a policy of extending political control over Acheh. This course of action, however, was rendered unnecessary, as the French defeat at Trafalgar in 1805 released British warships for service in the Indian Ocean. The danger from the French, however, continued to exist owing to the presence of French privateers but they ceased to operate after the termination of the Napoleonic Wars in 1814. The establishment of peace in Europe saw the restoration of the Dutch possessions in the Archipelago by the British. Soon fears were aroused of the probable Dutch domination of the main routes of the Archipelago, especially the Straits of Malacca. Consequently, the securing of free passage through the Straits of Malacca assumed great significance in the formulation of British policy in Southeast Asia in general and in Acheh in particular.

FALSIFICATION OF THE EULERIAN MOTIONS OF LITHOSPHERIC PLATES

2016 ◽  
pp. 0-0
Author(s):  
Jan KOZIAR
Keyword(s):  
Indian Ocean ◽  
Positive Result ◽  
Triple Junction ◽  
Plate Tectonics ◽  
Southwest Indian Ocean ◽  
Plate Motions ◽  
The Earth ◽  
Lithospheric Plates ◽  
The Indian Ocean ◽  
Ocean Ridge

Morgan (1968) tested the supposed Eulerian motion of lithospheric plates by calculation on a circuit around the Indian Ocean triple junction. The present analysis performed on a physical model shows that on a non-expanding Earth, the reconstructed Southwest Indian Ocean Ridge fails to close as it should according to the allegedly positive result of Morgan’s test, which is thereby shown to be in error. Wedge-shaped openings, appearing along all arms of the Indian Ocean triple junction during its reconstruction, are examples of Carey’s artifactual “gaping gores” which in general are one of the proofs of the Earth’s expansion. A global plan of plate motions based on the Eulerian principle is impossible and confirms Carey’s Arctic Paradox which is other proof of the expansion of the Earth. Space geodesy testing of expanding Earth is in fact testing of possible expansion of the plate tectonics model, not the real Earth. V-shaped openings between plates, when real, are not of Eulerian origin but are large sphenochasms in Carey’s sense caused by an expanding interior of the Earth.

The Paving Stone Theory of World Tectonics

2018 ◽  
Author(s):  
Roy Livermore
Keyword(s):  
Indian Ocean ◽  
Plate Tectonics ◽  
Earth Science ◽  
Transform Faults ◽  
Plate Motions ◽  
Euler’S Theorem ◽  
History Of ◽  
New Ideas ◽  
Entire History ◽  
The Indian Ocean

Tuzo Wilson introduces the concept of transform faults, which has the effect of transforming Earth Science forever. Resistance to the new ideas is finally overcome in the late 1960s, as the theory of moving plates is established. Two scientists play a major role in quantifying the embryonic theory that is eventually dubbed ‘plate tectonics’. Dan McKenzie applies Euler’s theorem, used previously by Teddy Bullard to reconstruct the continents around the Atlantic, to the problem of plate rotations on a sphere and uses it to unravel the entire history of the Indian Ocean. Jason Morgan also wraps plate tectonics around a sphere. Tuzo Wilson introduces the idea of a fixed hotspot beneath Hawaii, an idea taken up by Jason Morgan to create an absolute reference frame for plate motions.

scholarly journals Differential Influences of Teleconnections from the Indian and Pacific Oceans on Rainfall Variability in Southeast Asia

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 886
Author(s):  
Abdul Azim Amirudin ◽  
Ester Salimun ◽  
Fredolin Tangang ◽  
Liew Juneng ◽  
Muhamad Zuhairi
Keyword(s):  
Indian Ocean ◽  
Southeast Asia ◽  
El Niño ◽  
El Nino ◽  
Rainfall Variability ◽  
June July August ◽  
Rainfall Patterns ◽  
Negative Impacts ◽  
The Individual ◽  
June July

This study investigates the individual and combined impacts of El Niño and the positive Indian Ocean Dipole (IOD) on the Southeast Asia (SEA) rainfall variability. Using composite and partial correlation techniques, it is shown that both inter-annual events have individually distinct impacts on the SEA rainfall anomaly distribution. The results showed that the impacts of the co-occurrence of El Niño and IOD events are significant compared to the individual effects of pure El Niño or pure IOD. During June-July-August and September-October-November, the individual impacts of the pure El Niño and IOD events are similar but less significant. Both events caused negative impacts over the southern part of SEA during June-July-August (JJA) and propagated northeastward/eastward during September-October-November (SON). Thus, there are significant negative impacts over the southern part of SEA during the co-occurrence of both events. The differential impacts on the anomalous rainfall patterns are due to the changes in the sea surface temperature (SST) surrounding the region. Additionally, the differences are also related to the anomalous regional atmospheric circulations that interact with the regional SST. The anomalous Walker circulation that connects the Indian Ocean and tropical Pacific Ocean also plays a significant role in determining the regional anomalous rainfall patterns.

scholarly journals Circulation pattern controls of wet days and dry days in Free State, South Africa

2021 ◽  
Author(s):  
Chibuike Chiedozie Ibebuchi
Keyword(s):  
South Africa ◽  
Indian Ocean ◽  
Atmospheric Circulation ◽  
Southern Africa ◽  
Austral Summer ◽  
Free State ◽  
Austral Spring ◽  
Study Region ◽  
Southwest Indian Ocean ◽  
South Indian

AbstractAtmospheric circulation is a vital process in the transport of heat, moisture, and pollutants around the globe. The variability of rainfall depends to some extent on the atmospheric circulation. This paper investigates synoptic situations in southern Africa that can be associated with wet days and dry days in Free State, South Africa, in addition to the underlying dynamics. Principal component analysis was applied to the T-mode matrix (variable is time series and observation is grid points at which the field was observed) of daily mean sea level pressure field from 1979 to 2018 in classifying the circulation patterns in southern Africa. 18 circulation types (CTs) were classified in the study region. From the linkage of the CTs to the observed rainfall data, from 11 stations in Free State, it was found that dominant austral winter and late austral autumn CTs have a higher probability of being associated with dry days in Free State. Dominant austral summer and late austral spring CTs were found to have a higher probability of being associated with wet days in Free State. Cyclonic/anti-cyclonic activity over the southwest Indian Ocean, explained to a good extent, the inter-seasonal variability of rainfall in Free State. The synoptic state associated with a stronger anti-cyclonic circulation at the western branch of the South Indian Ocean high-pressure, during austral summer, leading to enhanced low-level moisture transport by southeast winds was found to have the highest probability of being associated with above-average rainfall in most regions in Free State. On the other hand, the synoptic state associated with enhanced transport of cold dry air, by the extratropical westerlies, was found to have the highest probability of being associated with (winter) dryness in Free State.

scholarly journals Cluster Analysis of Deep Water Sound Speed Profiles in Indian Ocean

2019 ◽  
Vol 310 ◽  
pp. 052048
Author(s):  
Hua Wang ◽  
Yunbo Li ◽  
Qinghong Li ◽  
Xiangjun Yu
Keyword(s):  
Cluster Analysis ◽  
Indian Ocean ◽  
Deep Water ◽  
Sound Speed

scholarly journals Variability in the Mozambique Channel Trough and Impacts on Southeast African Rainfall

2020 ◽  
Vol 33 (2) ◽  
pp. 749-765 ◽  
Author(s):  
Rondrotiana Barimalala ◽  
Ross C. Blamey ◽  
Fabien Desbiolles ◽  
Chris J. C. Reason
Keyword(s):  
Indian Ocean ◽  
Austral Summer ◽  
Western Indian Ocean ◽  
Strong Relationship ◽  
Ocean Basin ◽  
Moist Convection ◽  
South Indian Ocean ◽  
Mozambique Channel ◽  
Mascarene High ◽  
South Indian

AbstractThe Mozambique Channel trough (MCT) is a cyclonic region prominent in austral summer in the central and southern Mozambique Channel. It first becomes evident in December with a peak in strength in February when the Mozambique Channel is warmest and the Mascarene high (MH) is located farthest southeast in the Indian Ocean basin. The strength and the timing of the mean MCT are linked to that of the cross-equatorial northeasterly monsoon in the tropical western Indian Ocean, which curves as northwesterlies toward northern Madagascar. The interannual variability in the MCT is associated with moist convection over the Mozambique Channel and is modulated by the location of the warm sea surface temperatures in the south Indian Ocean. Variability of the MCT shows a strong relationship with the equatorial westerlies north of Madagascar and the latitudinal extension of the MH. Summers with strong MCT activity are characterized by a prominent cyclonic circulation over the Mozambique Channel, extending to the midlatitudes. These are favorable for the development of tropical–extratropical cloud bands over the southwestern Indian Ocean and trigger an increase in rainfall over the ocean but a decrease over the southern African mainland. Most years with a weak MCT are associated with strong positive south Indian Ocean subtropical dipole events, during which the subcontinent tends to receive more rainfall whereas Madagascar and northern Mozambique are anomalously dry.

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