What texture is eclogite?
coarse grained
The eclogites are coarse grained. They contain omphacite (35–45%, Tables 2a and 2b), clinozoisite (0–35%), glaucophane (0–20%), phengite (5–20%), garnet (5–10%), quartz (0–15%), and minor amounts of titanite.
What type of metamorphism is eclogite?
Eclogites typically result from high to ultrahigh pressure metamorphism of mafic rock at low thermal gradients of <10 °C/km (29 °F/mi) as it is subducted to the lower crust to upper mantle depths in a subduction zone.
What is the characteristics of eclogite?
A high-pressure, high-temperature, coarse-grained metamorphic rock consisting primarily of pink-red garnet (almadine-pyrope variety) and green pyroxene (omphacite, a sodium-rich variety). Eclogites may also contain small amounts of other high-pressure minerals such as kyanite, quartz, hornblende, and zoisite.
Why is eclogite dense?
The crust thickens by tectonic or igneous processes, eventually forming dense eclogite that detaches and sinks into the mantle. It reaches a level of neutral buoyancy and starts to warm up. Eventually it rises and forms a warm fertile patch in the mantle.
Where is eclogite found?
The eclogites have a relatively small presence and share of the metamorphic rocks in the Earth’s crust but are the main ingredients with peridotite of Earth layer (Section 5.1). Eclogite is a rare and significant rock formed only by conditions typically found in the mantle or the lowermost part of the thickened crust.
How is eclogite underwent metamorphism?
Their origin is of subducted basalt, metamorphosed to eclogite as a result of increased pressure, then subsequently brought to the surface through supra-subduction zone volcanism. The high density of eclogite explains its rarity in crustal exposures.
How did eclogite form?
Eclogites are typically formed by subduction of oceanic crust. Oceanic crust forms at mid-ocean ridges, where melting of the earth’s mantle produces a layered crust of mafic composition, basalts on top, gabbro below.
How does eclogite reach the surface?
One possibility is that eclogite rocks are broken into fragments and somehow squeezed to the surface as tectonic blocks. Some models of subduction zones include a channel of soft serpentinite immediately above the subducting plate. In such a ‘mélange’ rigid pips of eclogite may be squeezed towards the surface.
Where can eclogite be found?
Eclogite is a rare and significant rock formed only by conditions typically found in the mantle or the lowermost part of the thickened crust. The rock occurs with garnet peridotite in Greenland and other ophiolite complexes.
What minerals are in eclogite?
Eclogites consist primarily of green pyroxene (omphacite) and red garnet (pyrope), with small amounts of various other stable minerals—e.g., rutile. They are formed when volcanic or metamorphic rocks rich in such mafic minerals are subjected to extremely high pressures and moderate to relatively high temperatures.
Is eclogite a density?
The STP densities of peridotites vary from 3.3 to 3.47 g/cm3; eclogite densities range from 3.45 to 3.75 g/cm3.
Does eclogite form at low or high pressure?
Laboratory experiments have revealed that eclogites will crystallize from basaltic magma under very high pressure conditions common to the deeper portions of the Earth’s upper mantle, the mantle constituting the layer that lies between the crust and core and that comprises about two-thirds of the planet’s bulk.