7th Himalaya-Karakoram-Tibet Workshop
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The first Himalayan Workshop held in Leicester University in 1985 was so successful that it was then agreed to hold the informal conference and workshop annually. Subsequently the Himalayan Workshops were held in Vandoevre-les-Nancy, France in 1986, London (1987), Lausanne, Switzerland (1988), Milan, Italy (1990) and Grenoble, France (1991). The upsurge in research throughout the Himalayan and Tibetan regions in the last ten years has warranted these annual meetings, and the dissemination of new research throughout the Himalayan community has been invaluable. This year the meeting was held in the Department of Earth Sciences, Oxford University, under the auspices of The Geological Society, London, from 6-8 April 1992. Over 120 participants from 15 countries attended. The Himalayan chain has long been recognized as the world's most spectacular example of a continent-continent collision belt resulting from the collision of the Indian plate with the central Asian landmass some 50 Ma ago. Since then India has moved northwards with respect to Asia by over 2000 km at an average speed of 50mm a −1 resulting in compressional tectonics not only in the Himalaya to the south of the main Indus suture zone, but also active compression in the mountain ranges north of the Indus suture: the Karakoram, Hindu Kush, Pamirs, Kun Lun and Tien Shan, as well as uplift of the 5 km high Tibetan plateau. Crustal shortening has mainly been accommodated by thrusting and folding in the Himalaya, by internal, diffuse lithospheric thickening within the Tibetan plateau, by limited, underthrusting of theMargin (machine learning)
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Protolith
Felsic
Banded iron formation
Greenschist
Basement
Geochronology
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Continental Margin
Red beds
Diachronous
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Yilgarn Craton
Greenstone belt
Hornblende
Arsenopyrite
Dike
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During the last 10 m.y., the Nanga Parbat Haramosh Massif in the northwestern Himalaya has been intruded by granitic magmas, has undergone high‐grade metamorphism and anatexis, and has been rapidly uplifted and denuded. As part of an ongoing project to understand the relationship between tectonism and petrologic processes, we have undertaken an isotopic study of the massif to determine the importance of hydrothermal activity during this recent metamorphism. Our studies show that both meteoric and magmatic hydrothermal systems have been active over the last 10 m.y. We suggest that the rapid uplift of the massif created a dual hydrothermal system, consisting of a near‐surface flow system dominated by meteoric water and a flow regime at deeper levels dominated by magmatic/metamorphic volatiles. Meteoric fluids derived from glaciers near the summit of Nanga Parbat were driven deep into the massif along the transpressional faults causing δ 18 O and δD depletions in the gneisses and marked oxygen isotopic disequilibrium between mineral pairs from the fault zones. The discharge of these meteoric fluids occurs in active hot springs that are found along the steep faults that border the massif. At deeper levels within the massif, infiltration of low δ 18 O magmatic fluids caused δ 18 O depletions in the gneisses within the migmatite zone. These low δ 18 O fluids were derived from the young (<4 Ma), relatively low δ 18 O granites (∼8‰c) that are found within the core of the massif. Geochronological evidence in the form of fission track and 40 Ar/ 39 Ar cooling ages and U/Pb ages on accessory minerals from the granites and gneisses provide a constraint on the timing of fluid flow in the surface outcrops we examined. Fluid infiltration in the migmatite zone rocks located along the Tato traverse was coeval with metamorphism, granite emplacement, and rapid denudation, in the interval 0.8–3.3 Ma. Finally, we infer from the presence of active hot springs that significant flow systems continue to be active at depth within the central portion of the Nanga Parbat‐Haramosh Massif.
Massif
Leucogranite
Migmatite
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Structurally, the Hugoton embayment is a large, southward-plunging syncline that represents a northerly extension of the Anadarko basin. It is bounded on the east by the Pratt anticline, on the northeast by the Central Kansas uplift, on the northwest by the Las Animas arch, on the west by the Sierra Grande uplift, and on the southwest by the Amarillo uplift. The embayment is approximately 150 mi wide and 250 mi long. Subsidence began during the Early Ordovician and reached a maximum from the middle Mississippi through the early middle Permian. Rocks of Paleozoic, Mesozoic, and Cenozoic ages are present in the embayment. The section thickens toward the axis of the embayment where it is about 9500 ft. The Ordovician through Cambrian section attains a thickness of about 650 ft. The Devonian and Silurian are largely absent from the area. The Mississippian and Pennsylvanian sections are about 3000 ft thick. Excluding the Permian, the Mississippian and Pennsylvanian contain the highest exploration potential. An evaluation of the deeper zones in the underexplored areas of the embayment identified several structural and stratigraphic trends that are presently untested or remain underexplored. The trends can be separated into those controlled by early structural developments whichmore » persisted through the section and later structural stratigraphic events. The probability of finding new fields in the 500,000 to 5,000,000-bbl range is good.« less
Devonian
Anticline
Syncline
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