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Scourian Orogeny
The Scourian orogeny was an orogeny mountain building event 2.6 billion years ago during the Archean before the beginning of the Laxfordian orogeny (or potentially overlapping with the beginning of the Laxfordian. The orogeny is marked by northwest-southeast trending folds south of Laxford in northwest Scotland. The event affected the Lewisian gneiss The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleopro .... Rubidium-strontium dating indicated Scourian metamorphism took place between 2.6 and 2.7 billion years ago{{cite book , year=1977, title= Precambrian of the Northern Hemisphere, url=https://archive.org/details/precambriannorth00salo, url-access=limited, publisher=Elsevier, 50} References Archean orogenies Geology of Scotland ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orogeny
Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An '' orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere ( crust and uppermost mantle). A synorogenic process or event is one that occurs during an orogeny. The word "orogeny" () comes from Ancient Greek (, , + , , ). Although it was used before him, the term was employed by the American geologist G. K. Gilbert in 1890 to describe the process of mountain-building as distinguishe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archean
The Archean Eon ( , also spelled Archaean or Archæan) is the second of four eon (geology), geologic eons of History of Earth, Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth during the Archean was mostly a water world: there was continental crust, but much of it was under an ocean deeper than today's ocean. Except for some trace minerals, today's oldest continental crust dates back to the Archean. Much of the geological detail of the Archean has been destroyed by subsequent activity. The Earliest known life forms, earliest known life started in the Archean. Life was simple throughout the Archean, mostly represented by shallow-water microbial mats called stromatolites, and the atmosphere lacked free oxygen. Etymology and changes in classification The word ''Archean'' comes from the Greek word (), meaning 'beginning, origin'. It was first used in 1872, when it meant 'of the earliest geological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laxfordian Orogeny
The Laxfordian orogeny was an orogenic (mountain building) event between 1.9 and 1 billion years ago. It primarily affected the North Atlantic Craton, in particular a section that cleaved off during the Mesozoic as the Scottish Shield Fragment, part of the Lewisian complex within the Hebridean Terrane. The event produced deformation and high-grade metamorphism, migmatite formation and the emplacement granite and pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ... in the Loch Maree Group basement rocks between 1.9 and 1.8 billion years ago. From 1.6 to 1.4 billion years ago, brittle folds formed followed by crush belts in the final phase of the orogeny. Laxfordian orogenic belts have many similarities to the Nagssugtoqidian mobile belt in Greenland. The Laxfordian orogeny ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laxford
Laxford is a remote area in the far Northwest Highlands of Scotland around the River Laxford which runs northwest from Loch Stack to Laxford Bay. This bay is an inlet of Loch Laxford, a sea loch and Special Area of Conservation. The river is well known for its salmon fly fishing, indeed the name "Laxford" derives from the Norse for "salmon fjord". The area is important geologically, being a region of shear in the Moine Thrust. A road bridge, Laxford Bridge, crosses the river adjacent to the A838 and A894 roads, the road junction making the spot well known to tourists. Laxford is in Sutherland, in the Highland council area of Scotland; Scourie, away, is the nearest village. The area forms part of the North West Sutherland National Scenic Area, one of 40 such areas in Scotland, which are defined so as to identify areas of exceptional scenery and to ensure its protection by restricting certain forms of development. River Laxford The River Laxford runs some in a generally no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewisian Gneiss
The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoproterozoic age, ranging from 3.0–1.7 billion years ( Ga). They form the basement on which the Torridonian and Moine Supergroup sediments were deposited. The Lewisian consists mainly of granitic gneisses with a minor amount of supracrustal rocks. Rocks of the Lewisian complex were caught up in the Caledonian orogeny, appearing in the hanging walls of many of the thrust faults formed during the late stages of this tectonic event. Distribution The main outcrops of the Lewisian complex are on the islands of the Outer Hebrides, including Lewis, from which the complex takes its name. It is also exposed on several islands of the Inner Hebrides, small islands north of the Scottish mainland and forms a coastal strip on the mainland from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archean Orogenies
The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth during the Archean was mostly a water world: there was continental crust, but much of it was under an ocean deeper than today's ocean. Except for some trace minerals, today's oldest continental crust dates back to the Archean. Much of the geological detail of the Archean has been destroyed by subsequent activity. The earliest known life started in the Archean. Life was simple throughout the Archean, mostly represented by shallow-water microbial mats called stromatolites, and the atmosphere lacked free oxygen. Etymology and changes in classification The word ''Archean'' comes from the Greek word (), meaning 'beginning, origin'. It was first used in 1872, when it meant 'of the earliest geological age'. Before the Hadean Eon was recognized, the Archean sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
