Dr. SaMeH S. Ahmed

Associate Prof. of Environmental Engineering



Eclogite (play /ˈɛklət/) is a mafic (basaltic in composition) metamorphic rock; "mafic eclogite" is redundant. Eclogite is of special interest for at least two reasons. First, it forms at pressures greater than those typical of thecrust of the Earth. Second, being unusually dense rock, eclogite can play an important role in driving convectionwithin the solid Earth.

The fresh rock can be striking in appearance, with red to pink garnet (almandine-pyrope) in a green matrix ofsodium-rich pyroxene (omphacite). Accessory minerals include kyaniterutilequartzlawsonitecoesite,amphibolephengiteparagonitezoisitedolomitecorundum, and, rarely, diamondPlagioclase is not stable in eclogite.


Eclogite typically results from high-pressure metamorphism of mafic igneous rock (typically basalt or gabbro) as it plunges into the mantle in a subduction zone. Such eclogites are generally formed from precursor mineral assemblages typical of blueschist-facies or amphibolite-facies metamorphism. Eclogite can also form from magmas that crystallize and cool within the mantle or lower crust.

Eclogite facies

Eclogite facies is determined by the temperatures and pressures required to metamorphose basaltic rocks to an eclogite assemblage. The typical eclogite mineral assemblage is garnet (pyrope to almandine) plus clinopyroxene (omphacite).

Eclogites record pressures in excess of 1.2 GPa (45 km depth) at >400–1000 °C and usually in excess of 600-650 °C. This is high-pressure, medium- to high-temperature metamorphism. Diamond and coesite occur as trace constituents in some eclogites and record particularly high pressures. In fact, such ultrahigh-pressure (UHP) metamorphism has been defined as metamorphism within the eclogite facies but at pressures greater than those of the quartz-coesite transition (the two minerals have the same composition—silica). Some UHP rocks appear to record burial at depths greater than 150 km.

Eclogites containing lawsonite (a hydrous calcium-aluminium silicate) are rarely exposed at Earth's surface, although they are predicted from experiments and thermal models to form during normal subduction of oceanic crust at depths between ~ 45-300 kilometers[1]. The rarity of lawsonite eclogites therefore does not reflect unusual formation conditions but unusual exhumation processes. Lawsonite eclogite is known from the U.S. (Franciscan Complex of California; xenoliths in Arizona); Guatemala (Motagua fault zone), Corsica, Australia, the Dominican Republic, Canada (British Columbia), and Turkey.

Eclogite is the highest pressure metamorphic facies and is usually the result of advancement from blueschist metamorphic conditions.

Importance of eclogite

Photomicrograph of a thin section of eclogite from Turkey. Green omphacite (+ late chlorite) + pink garnet + blue glaucophane + colorless phengite.

Eclogite is a rare and important rock because it is formed only by conditions typically found in the mantle or the lowermost part of thickened crust.

Eclogites are helpful in elucidating patterns and processes of plate tectonics because many represent oceanic crust that has been subducted to depths in excess of 35 km and then returned to the surface.

Eclogite that is brought to shallow conditions is unstable, and retrograde metamorphism often occurs: secondary amphibole andplagioclase may form reaction rims on the primary pyroxene or garnet, and titanite may form rims about rutile. Eclogite may completely retrogress to amphibolite or granulite during exhumation. In some retrogressed eclogites and accompanying more silica-rich rocks, UHP (ultrahigh-pressure) metamorphism has been recognized only because of the preservation of coesite and/or diamond inclusions within trace minerals such as zircon and titanite.

Xenoliths of eclogite occur in kimberlite pipes of Africa, Russia, Canada, and elsewhere. Eclogites in granulite terranes are known from the Musgrave Block of central Australia where a continental collision took place at 550-530 Ma, resulting in burial of rocks to >45 km (15 kilobars) and rapid (in less than 10 million years!) exhumation via thrust faults prevented significant melting. Felsic rocks in these terranes contain sillimanitekyanitecoesiteorthoclase and pyroxene, and are rare, peculiar rocks formed by an unusual tectonic event.

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Mining Engineering

Mining engineering is an engineering discipline that involves practice, theory, science, technology, and the application of extracting and processing minerals from a naturally occurring environment. Mining engineering also includes processing minerals for additional value.

Environmental Engineering

Environmental engineers are the technical professionals who identify and design solutions for    environmental problems. Environmental engineers provide safe drinking water, treat and properly dispose of wastes, maintain air quality, control water pollution, and remediate sites contaminated due to spills or improper disposal of hazardous substances. They monitor the quality of the air, water, and land. And, they develop new and improved means to protect the environment.


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Assuit University (Home University), Egypt

Imperial College, London, UK

Faculty of Engineering, Al-Mergeb University, Libya

King Saud University, KSA

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Course 2016/17-1

  1. Computer Applications in Surveying  CE 473
  2. Surveying 1 CE 370
  3. Photogrammetry CE 474
  4. Surveying II  CE 371
  5. Design I  (round 4) CE 498

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Member of the Editorial Board: " Journal of Water Resources and Ocean Sciences"  2013


Participating in The Third International Conference on Water, Energy and Environment,(ICWEE) 2015 - American University of Sharjah, UAE 24-26 March 2015 with a Paper and Poster

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Participation  in the 6Th Student Conference

With a paper and oral presentation

From the Senior Design Project CE499 -35

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CE 370 Course

Surveying  I -  CE 370 - 2016-2017-1

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CE 371 Course

Surveying II - CE 371 - 2016-2017-1


First midterm exam



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Student Performance Records

CE473 Course

Computer Applications in Surveying

CE 473


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CE 474 Course

2015-2016-2 - Photogrammetry  CE474

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Report 1  Cameras Report


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CE 360 Course

Environmental Engineering 1

CE 360: Environmental Engineering 1


Y PP0-1-2-3,4 Power point
Y 1,2,3,4,5 Chapters

Water quality Poster + Climate Change Reports
will be announced (Quiz #2 will be using D2L- Online Quizzes


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GE 306 Course

Engineering Report Writing

GE 306: Engineering Report Writing

CE 499 Course

Senior Design 2 - CE 499

Meeting on 14-4-2015

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Paper title:

Evaluation of Groundwater Quality Parameters using Multivariate Statistics- a case Study of Majmaah, KSA


Abdullah A. Alzeer

Husam K. Almubark

Maijd M. Almotairi

CE 360-Summer Course

Environmental Engineering I

Welcome to CE360 second Term 2015-2016 

Engineering Practice

 Engineering Practice GE 307

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Civil and Environmental Engineering Department
College of Engineering, Majmaah University
Majmaah, P.O. 66, 11952, KSA

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CE 212 - Summer Course

Properties and Strength of Materials 1

CE 212

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CE 311- Summer Course

Soil Mechanics and Foundation Engineering

CE 311

M2+ model Answer + PP 1-9 = PDF 1-9 all are available

Sheets 2 + 4 with model Answers

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