Eklogite are rocks, which were metamorphosiert under eklogitfaziellen pressure and temperature conditions .
Eklogite with basaltischem Chemismus consist of green Klinopyroxen (omphazitreich: (Approx., well) (mg, aluminium) SI 2 O 6) and red garnet (pyropreich). Besides are often quartz, Disthen, rutile, Titanit and pyrite contained. Eklogite also granitischem Chemismus contain frequently aluminum-rich light mica (Phengit). For all kinds of Eklogiten the absence of Plagioklas (feldspar) is characteristic, which is diminished during increase in pressure after the reaction Albit = Jadeit + quartz. With extremely high pressure (ultrahigh pressure metamorphosis) also Coesit can,the high pressure modification contained by quartz, and diamond its.
Eklogite develop with high pressures off approx. 10 kbar (corresponds approx. 35 km depth) and middle to high temperatures (500 to 1000 degrees Celsius), thus in regions with low geothermal gradients. Thus Eklogite become frequentlyas indicator for Paläosubduktionszonen outstandingly. They can develop in rare cases in addition, at the basis of a strongly thickened continental crust. During lifting out to the earth's surface the Eklogite can be over-coined/shaped by retrograde metamorphosis, whereby itself minerals like e.g. Plagioklas, amphibole, Epidot and Biotit form, which however the actual eklogitfaziellen Mineralparagenese may not be added.
The investigation of Eklogiten is helpful with paläogeographischen reconstructions. If Eklogite with basaltischem (MORB = midocean back basalt) Chemismus arise, then these point on the earlier presence of an ocean. Over datings of the rockscan besides estimations over the early history of plate tectonics on earth be employed. The oldest found Eklogite originates from the paläoproterozoischen USA on mountains in Tanzania and has an age of 2 billion years.
See also: List of the rocks