Mike Searle is a field-based geologist working on Mountain Building Processes, notably along the Himalaya, Karakoram, Tibet ranges in Pakistan, India (Ladakh, Zanskar), Nepal and Butan, as well as the Oman - UAE ophiolite. He has also worked extensively in Burma (Myanmar), Thailand, Malaysia, the Aegean islands, Syria, Jordan, the Caledonides of Scotland and the Variscan belt of SW England.
Journal Of Geophysical Research: Solid Earth, Apr 1, 2021
The Semail ophiolite, a thick thrust sheet of Late Cretaceous oceanic crust and upper mantle, was... more The Semail ophiolite, a thick thrust sheet of Late Cretaceous oceanic crust and upper mantle, was obducted onto the previously rifted Arabian continental margin in the Late Cretaceous, and now forms part of the United Arab Emirates (UAE)‐Oman mountain belt. A deep foreland basin along the west and SW margin of the mountains developed during the obduction process, as a result of flexure due to loading of the ophiolite and underlying thrust sheets. The nature of the crust beneath the deep sedimentary basins that flank the mountain belt, and the extent to which the Arabian continental crust has thickened due to the obduction process are outstanding questions. We use a combination of active‐ and passive‐source seismic data to constrain the stratigraphy, velocity structure and crustal thickness beneath the UAE‐Oman mountains and its bounding basins. Depth‐migrated multichannel seismic reflection profile data are integrated in the modeling of traveltimes from long offset reflections and refractions, which are used to resolve the crustal thickness and velocity structure along two E‐W onshore/offshore transects in the UAE. Additionally, we apply the virtual deep seismic sounding method to distant earthquake data recorded along the two transects to image crustal thickness variations. Active seismic methods define the Semail ophiolite as a high‐velocity body dipping to the east at 40°–45°. The new crustal thickness model presented in this work provides evidence that a crustal root is present beneath the Semail ophiolite, suggesting that folding and thrusting during the obduction process may have thickened the pre‐existing crust by 16 km.
... The editors Yildirim Dilek and Sally Newcomb must be congratulated, not only on getting a rol... more ... The editors Yildirim Dilek and Sally Newcomb must be congratulated, not only on getting a roll-call of the most eminent ophiolite researchers to write papers, but also for putting the whole volume together. ... ISBN 0 906450 14 4. TORRENS, H. (ed.) 2003. ...
Petrologic and microstructural/crystal fabric data indicate that isotherms recorded in Greater Hi... more Petrologic and microstructural/crystal fabric data indicate that isotherms recorded in Greater Himalayan Series (GHS) schists and gneisses in the footwall to the South Tibetan Detachment System (STDS) have undergone extreme telescoping during penetrative flow associated with southward extrusion of the GHS. In the Rongbuk Valley, to the north of Mount Everest, we have made three vertical sampling traverses from the STDS down into the GHS and estimated temperatures associated with penetrative deformation using the ...
After the summer field season of 1989 in the Pakistani Karakoram, I drove to Oxford, the ‘city of... more After the summer field season of 1989 in the Pakistani Karakoram, I drove to Oxford, the ‘city of dreaming spires’ and arrived in the Department of Earth Sciences. In those days Oxford was probably the best field-geology ‘hard-rock’ department in the country and one of the best in the world. It was a wonderful place for me, buzzing with excitement and full of talented geologists working on projects all over the world. John Platt had post-graduate students working on several projects in the European Alps and the Spanish Betics, Simon Lamb was starting a major new field project in the Andes of Bolivia, and the department had some of the world’s leading igneous petrologists working on volcanic and granitic rocks all over the world. The department was overflowing and I was given an office on the top floor of the ‘annexe’ a wonderful old Victorian building at 62, Banbury Road. My office was up in the attic and I called this grandly the ‘Oxford Centre of Himalayan Research’. Right across the Banbury Road was an excellent public house, the Rose and Crown on North Parade, and we used to congregate there regularly for discussions on geology, and the world in general over a pint or two of traditional real ale. It was an excellent life. In the 1830s the first Professor of Geology in Oxford was the Reverend William Buckland who naturally came with a lot of religious baggage. Buckland was a bit of an eccentric in many ways including living with and eating a whole variety of wild animals and doing his geological fieldwork dressed in full academic gown. Following Buckland the department settled down to a more conventional geological approach, studying the stratigraphy and palaeontology of Oxfordshire. By the 1950s Oxford had become one of the leading departments of geology and mineralogy in the world. The head of department was Lawrence Wager, who had made his name studying the classic Skaergaard igneous intrusion of Greenland. Wager had earlier joined the 1933 Everest expedition climbing to 27,500 feet on the north ridge and collecting an extremely useful set of samples from the north slopes of Everest.
At 00.58 GMT (7.58 local time) on Sunday, 26 December 2004 a massive earthquake occurred off the ... more At 00.58 GMT (7.58 local time) on Sunday, 26 December 2004 a massive earthquake occurred off the north-west coast of Sumatra. The earthquake measured between magnitude 9.0 and 9.3 on the Richter scale with its epicentre at 3.32oN, 95.85oE, and occurred at a depth of approximately 30 kilometres. It was the second largest earthquake recorded since instrumental records began and was the deadliest natural disaster in recorded history. The earthquake and the resulting tsunami are estimated to have killed at least 228,000 people across fifteen countries bordering the Indian Ocean. The worst affected countries were Indonesia, Sri Lanka, India, Thailand, Burma, the Maldives, and Somalia. The earthquake occurred on the subduction zone interface between the down-going Indian Ocean plate and the overriding Burma–Andaman–Sumatra plate. It ruptured approximately 1600 kilometres’ length of the plate boundary from Sumatra all the way north to the Burmese coast, travelling at 2–3 kilometres per second. Aftershocks continued unrelentingly for over four months after the earthquake, several reaching magnitude 7.5 as far north as the northern Andaman Islands. The seismic waves indicated a thrust fault earthquake that tilted the surface up to the south-west and down to the north-east. The ground surface was elevated as much as 11 metres at the epicentre, with the tilted surface sinking up to one metre further to the north-east, offshore Sumatra. During the rupture, the Burma plate slipped as much as 15 metres horizontally as the Indian Ocean plate slipped beneath. The force of the quake perceptibly shifted the Earth’s axis, raised sea level globally and speeded Earth’s rotation. It has been suggested that the earthquake shortened the length of the day by 2.68 microseconds, because of the decrease in oblateness of the Earth. The earthquake caused the Earth to wobble on its axis by up to 2.5 cm in the direction of 145o east longitude. The natural ‘Chandler wobble’, a small motion in the Earth’s axis of rotation (the motion that occurs when the spinning object is not a perfect sphere) can be up to 9 metres over 433 days, so this eventually offsets the comparatively minor wobble produced by the earthquake.
Journal Of Geophysical Research: Solid Earth, Apr 1, 2021
The Semail ophiolite, a thick thrust sheet of Late Cretaceous oceanic crust and upper mantle, was... more The Semail ophiolite, a thick thrust sheet of Late Cretaceous oceanic crust and upper mantle, was obducted onto the previously rifted Arabian continental margin in the Late Cretaceous, and now forms part of the United Arab Emirates (UAE)‐Oman mountain belt. A deep foreland basin along the west and SW margin of the mountains developed during the obduction process, as a result of flexure due to loading of the ophiolite and underlying thrust sheets. The nature of the crust beneath the deep sedimentary basins that flank the mountain belt, and the extent to which the Arabian continental crust has thickened due to the obduction process are outstanding questions. We use a combination of active‐ and passive‐source seismic data to constrain the stratigraphy, velocity structure and crustal thickness beneath the UAE‐Oman mountains and its bounding basins. Depth‐migrated multichannel seismic reflection profile data are integrated in the modeling of traveltimes from long offset reflections and refractions, which are used to resolve the crustal thickness and velocity structure along two E‐W onshore/offshore transects in the UAE. Additionally, we apply the virtual deep seismic sounding method to distant earthquake data recorded along the two transects to image crustal thickness variations. Active seismic methods define the Semail ophiolite as a high‐velocity body dipping to the east at 40°–45°. The new crustal thickness model presented in this work provides evidence that a crustal root is present beneath the Semail ophiolite, suggesting that folding and thrusting during the obduction process may have thickened the pre‐existing crust by 16 km.
... The editors Yildirim Dilek and Sally Newcomb must be congratulated, not only on getting a rol... more ... The editors Yildirim Dilek and Sally Newcomb must be congratulated, not only on getting a roll-call of the most eminent ophiolite researchers to write papers, but also for putting the whole volume together. ... ISBN 0 906450 14 4. TORRENS, H. (ed.) 2003. ...
Petrologic and microstructural/crystal fabric data indicate that isotherms recorded in Greater Hi... more Petrologic and microstructural/crystal fabric data indicate that isotherms recorded in Greater Himalayan Series (GHS) schists and gneisses in the footwall to the South Tibetan Detachment System (STDS) have undergone extreme telescoping during penetrative flow associated with southward extrusion of the GHS. In the Rongbuk Valley, to the north of Mount Everest, we have made three vertical sampling traverses from the STDS down into the GHS and estimated temperatures associated with penetrative deformation using the ...
After the summer field season of 1989 in the Pakistani Karakoram, I drove to Oxford, the ‘city of... more After the summer field season of 1989 in the Pakistani Karakoram, I drove to Oxford, the ‘city of dreaming spires’ and arrived in the Department of Earth Sciences. In those days Oxford was probably the best field-geology ‘hard-rock’ department in the country and one of the best in the world. It was a wonderful place for me, buzzing with excitement and full of talented geologists working on projects all over the world. John Platt had post-graduate students working on several projects in the European Alps and the Spanish Betics, Simon Lamb was starting a major new field project in the Andes of Bolivia, and the department had some of the world’s leading igneous petrologists working on volcanic and granitic rocks all over the world. The department was overflowing and I was given an office on the top floor of the ‘annexe’ a wonderful old Victorian building at 62, Banbury Road. My office was up in the attic and I called this grandly the ‘Oxford Centre of Himalayan Research’. Right across the Banbury Road was an excellent public house, the Rose and Crown on North Parade, and we used to congregate there regularly for discussions on geology, and the world in general over a pint or two of traditional real ale. It was an excellent life. In the 1830s the first Professor of Geology in Oxford was the Reverend William Buckland who naturally came with a lot of religious baggage. Buckland was a bit of an eccentric in many ways including living with and eating a whole variety of wild animals and doing his geological fieldwork dressed in full academic gown. Following Buckland the department settled down to a more conventional geological approach, studying the stratigraphy and palaeontology of Oxfordshire. By the 1950s Oxford had become one of the leading departments of geology and mineralogy in the world. The head of department was Lawrence Wager, who had made his name studying the classic Skaergaard igneous intrusion of Greenland. Wager had earlier joined the 1933 Everest expedition climbing to 27,500 feet on the north ridge and collecting an extremely useful set of samples from the north slopes of Everest.
At 00.58 GMT (7.58 local time) on Sunday, 26 December 2004 a massive earthquake occurred off the ... more At 00.58 GMT (7.58 local time) on Sunday, 26 December 2004 a massive earthquake occurred off the north-west coast of Sumatra. The earthquake measured between magnitude 9.0 and 9.3 on the Richter scale with its epicentre at 3.32oN, 95.85oE, and occurred at a depth of approximately 30 kilometres. It was the second largest earthquake recorded since instrumental records began and was the deadliest natural disaster in recorded history. The earthquake and the resulting tsunami are estimated to have killed at least 228,000 people across fifteen countries bordering the Indian Ocean. The worst affected countries were Indonesia, Sri Lanka, India, Thailand, Burma, the Maldives, and Somalia. The earthquake occurred on the subduction zone interface between the down-going Indian Ocean plate and the overriding Burma–Andaman–Sumatra plate. It ruptured approximately 1600 kilometres’ length of the plate boundary from Sumatra all the way north to the Burmese coast, travelling at 2–3 kilometres per second. Aftershocks continued unrelentingly for over four months after the earthquake, several reaching magnitude 7.5 as far north as the northern Andaman Islands. The seismic waves indicated a thrust fault earthquake that tilted the surface up to the south-west and down to the north-east. The ground surface was elevated as much as 11 metres at the epicentre, with the tilted surface sinking up to one metre further to the north-east, offshore Sumatra. During the rupture, the Burma plate slipped as much as 15 metres horizontally as the Indian Ocean plate slipped beneath. The force of the quake perceptibly shifted the Earth’s axis, raised sea level globally and speeded Earth’s rotation. It has been suggested that the earthquake shortened the length of the day by 2.68 microseconds, because of the decrease in oblateness of the Earth. The earthquake caused the Earth to wobble on its axis by up to 2.5 cm in the direction of 145o east longitude. The natural ‘Chandler wobble’, a small motion in the Earth’s axis of rotation (the motion that occurs when the spinning object is not a perfect sphere) can be up to 9 metres over 433 days, so this eventually offsets the comparatively minor wobble produced by the earthquake.
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