The West Crocker formation of northwest Borneo: A Paleogene accretionary prism

Author(s):  
Joseph J. Lambiase ◽  
Tan Yaw Tzong ◽  
Amelia G. William ◽  
Michael D. Bidgood ◽  
Patrice Brenac ◽  
...  
Keyword(s):  
2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohammad Mokhtari ◽  
Ahmad Ala Amjadi ◽  
Leila Mahshadnia ◽  
Mandana Rafizadeh

Abstract The Makran Accretionary Wedge (900 km across) is a consequence of northward subduction of the oceanic part of the Arabian Plate beneath the Lut and Afghan blocks in the northwestern Indian Ocean. It has a complicated tectonic setting as it is located at a triple junction with the Indian Plate. Thick sedimentary layers, a shallow angle of the subducting slab and a large width of the subduction zone, ca. 500–600 km from volcanic arc to active wedge front, are some of the foremost and distinctive characteristics of the Makran Subduction Zone (MSZ). The MSZ is likely divided into at least two segments: the west and the east possibly separated by a sinistral fault known as the Sonne Fault. A division is also inferred from seismicity as it is higher in the east when compared to the west. With the exception of a notable trench, all other characteristics of an accretionary prism observed in well-studied subduction zone can be identified or inferred in the Makran. Three long seismic profiles of the western Makran (200 km long each, with shot points interval of 20 km and receivers interval of 700 m) have recently been acquired. Using these datasets, improved structural/velocity models for the western Makran were developed. This review aims to contribute to achieving a better understanding of the seismotectonic setting and dynamics of the Makran Subduction Zone as it feeds to a refined understanding of the tsunami hazard in the region.


1992 ◽  
Vol 29 (10) ◽  
pp. 2104-2117 ◽  
Author(s):  
C. Relf

Late Archean structures in the west-central part of the Slave Province formed during two separate orogenic events. Evidence for early folding and thrusting in an accretionary prism is confined to a narrow belt along the east margin of an older microcontinent (the Anton terrane) in the west part of the province. Structures related to this event are overprinted by regional low-pressure metamorphism. Subsequent shortening occurred in a continental-arc setting in which folding and faulting was accompanied by calc-alkaline magmatism and regional low-pressure metamorphism. Although the entire region was affected, the bulk of shortening during the second orogenic event occurred east of the early fold and thrust belt. The first orogenic event produced a suture zone between old continental crust to the west and juvenile rocks to the east, and during the second orogenic event rocks on either sides of the suture were tectonically underplated and intruded.


Author(s):  
O. Mudroch ◽  
J. R. Kramer

Approximately 60,000 tons per day of waste from taconite mining, tailing, are added to the west arm of Lake Superior at Silver Bay. Tailings contain nearly the same amount of quartz and amphibole asbestos, cummingtonite and actinolite in fibrous form. Cummingtonite fibres from 0.01μm in length have been found in the water supply for Minnesota municipalities.The purpose of the research work was to develop a method for asbestos fibre counts and identification in water and apply it for the enumeration of fibres in water samples collected(a) at various stations in Lake Superior at two depth: lm and at the bottom.(b) from various rivers in Lake Superior Drainage Basin.


1964 ◽  
Vol 2 (01) ◽  
pp. 6-12
Keyword(s):  
The West ◽  

In the West Nile District of Uganda lives a population of white rhino—those relies of a past age, cumbrous, gentle creatures despite their huge bulk—which estimates only 10 years ago, put at 500. But poachers live in the area, too, and official counts showed that white rhino were being reduced alarmingly. By 1959, they were believed to be diminished to 300.


2009 ◽  
Author(s):  
George Pinckard
Keyword(s):  

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