Mineral chemistry and thermobarometry of mafic pods in the Liverpool Land Eclogite Terrane (LLET) provide insight into potential relationships with regional high-pressure (HP) and ultrahigh-pressure (UHP) terranes such as the North East Greenland Eclogite Province (NEGEP), the Western Gneiss Region (WGR), and HP granulites in the East Greenland Caledonides at Payer Land. Grt-cpx thermometry and jadeite barometry performed on garnet and omphacite cores in a sequence of retrogressed eclogites give minimum and average P-T values across six samples for eclogite at 18.4 ± 3.7 kbar at 764 ± 156 °C. Granulite facies conditions based on early retrograde Opx-Plag symplectites, garnet rim compositions, and relict omphacite grains give P-T values at 12.7 ± 0.6 kbar at 860 ± 10 °C, based on grt-cpx thermometry and the opx-grt-pl-qtz equilibra. Late retrograde amphibolite facies conditions, marked by matrix plagioclase and biotite and orthopyroxene symplectite replacement by hornblende symplectites, give mean P-T values of 6.8 ± 0.4 kbar at 740 ± 150 °C, based on grt-cpx thermometry and the grt-hbl-plag-qtz equilibra. Thermometers and barometers yield a qualitative P-T path from lower eclogite facies pressures through the granulite facies via hot isothermal and static decompression, preserving symplectite textures, to amphibolite facies conditions via isobaric cooling. The path is consistent with low-pressure WGR eclogites and suggests affinities between the LLET and Baltica.

Studium pevných inkluzí vybraných minerálů eklogitů, peridotitů a granulitů Kutnohorské oblasti English abstract Felsic granulites with lenses and boudins of garnet peridotites and eclogites, for which UHP conditions have been obtained, commonly occur in the Moldanubian Zone of the Bohemian Massif. However, it is not clear when and how the HP-UHPM rocks were emplaced into the host granulites. The most important question that remains is, whether the felsic granulites also experienced UHP metamorphism. By studying solid phase inclusions and compositional zoning in resistant phases as garnet, we provide evidence of prograde metamorphism of felsic rocks prior to their granulite facies overprint. Finding mono-mineral inclusion of Ti-rich phengite point to prograde evolution of the rocks.Polyphase inclusions of phengite and biotite indicate that it was previously Ti-poor phengite. Another important inclusion is graphite, which could be remnant of micro-diamond inclusion. Well-preserved prograde zoning of major elements in garnet from the felsic granulites is supported by zoning patterns of trace elements, such as titanium, chromium and yttrium and rare earth elements. Both these groups of elements remain heterogeneous at a micro-scale. The garnet profiles reveal that the rocks preserved signs of multiple stages...

This research studies 6 eclogites from Qinglongshan Donghai in the Sulu ultrahigh-pressure (UHP) province, eastern China. Petrographic microscope, Ramam spectrometer, scanning electron microscope (SEM) and transmission electron microscope (TEM) are utilized to identify mineral compositions, microstructures and mineral precipitates. Optical observations show the eclogites with the following mineral assemblage: garnet + omphacite + amphibole + epidote + rutile ¡Ó quartz ¡Ó phengite ¡Ó kyanite ¡Ó coesite pseudomorph ¡Ó apatite ¡Ó talc. Oriented mineral precipitates are found within omphacite and within apatites. The parallel precipitates in omphacite are quartz rods confirmed by electron probe microanalysis (EPMA) and TEM diffraction patterns. The direction of the long axes of the quartz rods seem to have relation with the cleavage and with the parting of omphacite. The direction of the long axis of quartz is not necessarily the c axis direction of quartz. Pargasite is intergrown with quartz and the amounts of both minerals seem to have a positive relation. Pargasite contain element K which is not found in omphacite and there is no obvious crystallographic relation between quartz, pargasite, and omphacite. There is amphibole exsolved from the omphacite and the crystallographic axes of tht exsolved amphibole parallel to those of omphacite. The a and c parameters for the two phases are equal while the b parameter of the amphibole is almost twice that of omphacite. A two-stage growth mechanism for quartz and amphibole intergrown within omphacite is proposed: (1) very fine quartz rods exsolved (or aided with infilling fluids) from a supersilicic clinopyroxene during decompression, creating grain boundaries between quartz rods and host, (2) growth of amphibole and quartz along the grain boundaries with fluid participation and an expense of omphacite during retrograde metamorphism. There are two different precipitates within apatites in different eclogites. One of the precipitates is calcium sulfate (anhydrite or gypsum) and the other is ferrous sulfide (pyrrhotite?). There was no report about calcium sulfate within apatite in UHP rocks before. The formation of sulfide (reduced) or sulfate (oxidized) is controlled by the fugacity of oxygen. According to the previous reports and the discoveries of this research, there are many different kinds of precipitates containing silicate incompatible elements in apatites. It can¡¦t be ruled out that the precipitates exsolved from apapites but apatites are more likely to act as sinks of silicate incompatible elements and different minerals precipitated within apatites under different redox conditions rather than exsolution processes.

Oxygen isotopes and major and trace element geochemistry have been used to evaluate the geochemical and tectonic history of a Franciscan hornblende-amphibolite and a eclogite block from Ring Mountain, Tiburon and three eclogite/blueschist blocks from Jenner Beach, California, all blocks have experienced varying amounts of retrogression. Relative to the presumed basaltic protolith, enrichments in large ion lithophile elements (LILEs) indicate interaction with sediment derived fluids in the retrograde eclogite and retrograde blueschist samples and high Mg, Cr, and Ni in actinolite rind indicate interaction with ultramafic rock. The [delta]¹⁸O values of chlorite from the Ring Mountain hornblende-amphibolite and the eclogite block have a narrow range of [delta]¹⁸O values (+7.7-8.2%₀, n=8) and actinolite from actinolite rind on the eclogite block from Ring Mountain and the blueschist/eclogite blocks from Jenner Beach are (+7.8-8.5%₀, n=5). Chlorite-actinolite geothermometry yields temperatures of 200-280°C for actinolite rind formation. Additionally, the [delta]¹⁸O values of both chlorite and actinolite at these temperatures indicates equilibrium with the measured value of Tiburon serpentinites, (7.6 to 8.1%₀, n = 3 Wenner and Taylor, 1974). Oxygen isotope analyses of garnet mineral separates from the eclogite and hornblende-amphibolite from Ring Mountain have [delta]¹⁸O values of +6.8±0.3%₀ (n=7), and +8.2±0.2%₀ (n=7), respectively. Garnets from the three eclogite/blueschist blocks at Jenner Beach have a [delta]¹⁸O value of +9.8±0.7%₀, (n=23). The difference in [delta]¹⁸O values of garnets between the high-grade blocks is likely due to in situ hydrothermal alteration of the seafloor basalt prior to subduction. The geochemical trends can be explained by a model in which during the early stages of subduction pieces of altered oceanic crust are detached from the downgoing slab and incorporated into the mantle wedge soon after reaching peak eclogite or amphibolite facies conditions. As subduction continues, the hanging wall cools and fluids released from subducted sediments infiltrate the overlying mantle wedge. As the blocks cool they develop a retrograde blueschist facies overprint under relatively static conditions. With cooling of the hanging wall and infiltration of sedimentary fluids, serpentinization induces reaction between the blocks and surrounding mantle wedge and Mg-rich actinolite rind is formed. The blocks are then plucked from the mantle wedge and incorporated into the subduction channel where they flow back to the surface via corner flow. / text

No description available.

Variations in major, minor, and trace elements compositions and ratios, as well as isotope ratios are all useful tools in studying the composition of the Earth’s mantle, and heterogeneities present therein. Since the mantle itself doesn’t easily lend itself to study, ocean island basalt (OIBs) are commonly used as a proxy due to compositional differences combined with the range of origination depth, a combination that allows them to represent the heterogeneity of the mantle, sampling everything from the core mantle boundary to the old or recent additions of recycled oceanic crust. Fogo, being one of the most active volcanoes in the world, continuously samples the interior of our planet, and as such is a prime location for studies of mantle geochemistry. This study aims to determine the origin of the mantle lithologies present at Fogo. The study is a continuation and extension of the studies conducted by Barker et al. (2014) and Magnusson (2016). This study utilises major, minor, and trace element geochemistry in clinopyroxene and olivine phenocrysts, as well as Ni-isotopes from whole rock samples. Using the relative values of Ni, Mn, and trace elements and their ratios in olivine and clinopyroxene phenocrysts we aim to further unravel the mechanics of the creation of ocean islands and provide additional constraints regarding the mechanics of the formation of heterogeneities in the Earth’s mantle. This study will focus on Ni* and Mn* in olivine phenocrysts, trace element composition and ratios of olivine phenocrysts and clinopyroxene phenocrysts, and Ni-isotope data.  This study found evidence for both pyroxenite, carbonatite, and carbonated eclogite source lithologies at Fogo. A correlation between La/Sm and δ60Ni was also found, indicating a control on the δ60Ni by source pyroxenite. This study suggests a carbonated eclogite origin for the lithologies present at Fogo, which would have hosted the majority of the olivine phenocrysts. The phenocrysts then resided within a separated carbonatite melt fraction that either contaminated or metasomatized a pyroxenite melt where the clinopyroxene phenocrysts nucleated. The melt then evolved to an alkali basalt melt through melt-rock reactions, principally via the dissolution of orthopyroxenes and concomitant precipitation of clinopyroxene and olivine (Zhang, Chen, Jackson & Hofmann 2017).

Kimberlite, an ultrabasic diamond-bearing hypabyssal rock-type which has its origin in the Earth's upper mantle, characteristically contains rare, well-rounded xenoliths of peridotite and eclogite. These xenoliths, which undoubtedly originate from some considerable depth below the Earth's surface, possibly represent samples of upper mantle material. They have received much attention from earth scientists and numerous theories as to their origin have been proposed. Forty-two selected peridotite xenoliths from the Bultfontein, Wesselton, Dutoitspan and Roberts Victor kimberlite pipes of the Kimberley area, South Africa, and 24 eclogite xenoliths from the Roberts Victor pipe have been examined in detail using a variety of petrological and mineralogical techniques. The petrologic research comprises conventional petrographic studies, the determination of accurate modal compositions and the presentation of 22 new whole-rock chemical analyses, nine of which are of garnet peridotite, four of spinel peridotite and nine of eclogite, one being a diamondiferous specimen. Detailed mineralogical studies of the constituent minerals of the xenoliths comprises descriptive mineralogy, in most cases an estimation of the compositions of these minerals from the measurement of physical properties, X-ray powder diffraction data and the presentation of 21 new chemical analyses of pure mineral separates. This includes five analyses of clivine, five of orthopyroxene, eight of garnet, one of chrome diopside and two of omphacite. The results of the investigation have shown that the peridotites consist essentially of forsterite and enstatite with minor or trace amounts of one or more of pyrope-rich garnet, chrome diopside, chrome spinel, phlogopite and rarely graphite, and often exhibit features consistent with plastic movement and tectonic deformation. The peridotites are believed to be derived from an ultrabasic upper mantle, which is both chemioally and physically zoned. The eclogite xenoliths, which are composed mainly of pyrope-almandine garnet and omphacitic clinopyroxene and occasionally contain kyanite, corundum and diamond, are not samples of a primary eclogitic upper mantle nor the products of an eclogite fractionation related to kimberlite genesis. Chemically they are not typical of extrusive basalts and probably either represent pockets of partially fractionated basic magma trapped at mantle-level in an eclogite-stable environment or samples of high-grade crustal metamorphic eclogite accidentally incorporated into the Roberts Victor kimberlite.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The sodic and leucocratic Tonalite, Trondhjemite and Granodiorite (TTG) granitoid series of rocks characterise Paleo- to Meso- Archaean felsic continental crust, yet are uncommon in the post-Archaean rock record. Consequently, petrogenetic studies on these rocks provide valuable insight into the creation and evolution of Earth’s early continental crust. The highpressure (HP)-type of Archaean TTG magmas are particularly important in this regard as their geochemistry requires that they are formed by high-pressure melting of a garnet-rich eclogitic source. This has been interpreted as evidence for the formation of these magmas by anatexis of the upper portions of slabs within Archaean subduction zones. In general, TTG magmas have been assumed to arise through fluid-absent partial melting of metamafic source rocks. Therefore, very little experimental data on fluid-present eclogite melting to produce Archaean TTG exist, despite the fact that water drives magmatism in modern arcs. Consequently, this study experimentally investigates the role of fluid-present partial melting of eclogite-facies metabasaltic rock in the production of Paleo- to Meso-Archaean HP-type TTG melts. Experiments are conducted between 1.6 GPa and 3.0 GPa and 700 ºC and 900 ºC using natural and synthetic eclogite, and gel starting materials of low-K2O basaltic composition. Partial melting of the natural and synthetic eclogite occurred between 850 ºC and 870 ºC at pressures above 1.8 GPa, and the melting reaction is characterised by the breakdown of sodic clinopyroxene, quartz and water: Qtz + Cpx1 + H2O ± Grt1 = Melt + Cpx2 ± Grt2. The experimental melts have the compositions of sodic peraluminous trondhjemites and have compositions that are similar to the major, trace and rare earth element composition of HPtype Archaean TTG. This study suggests that fluid-present eclogite melting is a viable petrogenetic model for this component of Paleo- to Meso-Archaean TTG crust. The nature of the wet low-K2O eclogite-facies metamafic rock solidus has been experimentally defined and inflects towards higher temperatures at the position of the plagioclase-out reaction. Therefore, the results indicate that a crystalline starting material is necessary to define this solidus to avoid metastable melting beyond temperatures of the Pl + H2O + Qtz solidus at pressures above plagioclase stability. Furthermore, this study uses numerical and metamorphic models to demonstrate that for reasonable Archaean mantle wedge temperatures within a potential Archaean subduction zone, the bulk of the water produced by metamorphic reactions within the slabs is captured by an anatectic zone near the slab surface. Therefore, this geodynamic model may account for HP-type Archaean TTG production and additionally provides constraints for likely Archaean subduction. The shape of the relevant fluid-present solidus is similar to the shape of the pressure-temperature paths followed by upper levels of the proposed Archaean subducting slab, which makes water-fluxed slab anatexis is very dependant on the temperature in the mantle wedge. I propose that cooling of the upper mantle by only a small amount during the late Archaean ended fluid-present melting of the slab. This allowed slab water to migrate into the wedge and produce intermediate composition magmatism which has since been associated with subduction zones. / AFRIKAANSE OPSOMMING: Die reeks natruimhoudende en leukokraties Tonaliet, Trondhjemiet en Granodioriet (TTG) felsiese stollingsgesteentes is kenmerkend in die Paleo- tot Meso-Argeïkum felsiese kontinentale kors, maar is ongewoon in die post-Argeïese rots rekord. Gevolglik, petrogenetiese studies op hierdie rotse verskaf waardevolle insig in die skepping en evolusie van die aarde se vroeë kontinentale kors. Die hoë-druk (HD)-tipe van die Argeïkum TTG magmas is veral belangrik in hierdie verband as hulle geochemie vereis dat hulle gevorm word deur hoë druk smelting van 'n granaat-ryk eklogitiese bron. Dit word interpreteer as bewys vir die vorming van hierdie magmas deur smelting van die boonste gedeeltes van die blaaie in Argeïese subduksie sones. TTG magmas in die algemeen, is veronderstel om op te staan deur middel van water-afwesig gedeeltelike smelting van metamafiese bron rotse. Daarom bestaan baie min eksperimentele data op water-teenwoordig eklogiet smelting om Argeïkum TTG te produseer, ten spyte van die feit dat water magmatisme dryf in moderne boë. Gevolglik is hierdie studie ‘n eksperimentele ondersoek in die rol van water-teenwoordig gedeeltelike smelting van eklogiet-fasies metamafiese rots in die produksie van Paleo- tot Meso-Argeïkum HD-tipe TTG smelte. Eksperimente word uitgevoer tussen 1.6 GPa en 3.0 GPa en 700 ºC en 900 ºC met behulp van natuurlike en sintetiese eklogiet, en gel begin materiaal van lae-K2O basaltiese samestelling. Gedeeltelike smelting van die natuurlike en sintetiese eklogiet het plaasgevind tussen 850 ºC en 870 ºC te druk bo 1.8 GPa, en die smeltings reaksie is gekenmerk deur die afbreek van natruimhoudende klinopirokseen, kwarts en water: Qtz + Cpx1 + H2O ± Grt1 = Smelt + Cpx2 ± Grt2. Die eksperimentele smelte het die komposisies van natruimhoudende trondhjemites en is soortgelyk aan die hoof-, spoor- en seldsame aard element samestelling van HD-tipe Argeïkum TTG. Hierdie studie dui daarop dat water-teenwoordig eklogiet smelting 'n lewensvatbare petrogenetiese model is vir hierdie komponent van Paleo- tot Meso-Argeïkum TTG kors. Die aard van die nat lae-K2O eklogietfasies metamafiese rock solidus is eksperimenteel gedefinieër en beweeg na hoër temperature by die posisie van die plagioklaas-out reaksie. Daarom dui die resultate daarop dat 'n kristallyne materiaal nodig is om hierdie solidus te definieër en metastabiele smelting buite temperature van die Pl + H2O + Qtz solidus druk bo plagioklaas stabiliteit te vermy. Verder maak hierdie studie gebruik van numeriese en metamorfiese modelle om aan te dui dat die grootste deel van die water geproduseer deur metamorfiese reaksies binne die blaaie bestaan vir redelike Argeïkum mantel wig temperature binne 'n potensiële Argeïkum subduksie sone, en word opgevang deur 'n smelting sone naby die blad oppervlak. Daarom kan hierdie geodinamies model rekenskap gee vir HD-tipe Argeïkum TTG produksie en dit bied ook die beperkinge vir waarskynlik Argeïese subduksie. Die vorm van die betrokke waterteenwoordig solidus is soortgelyk aan die vorm van die druk-temperatuur paaie gevolg deur die boonste vlakke van die voorgestelde Argeïkum subderende blad, wat water-vloeiing blad smeltingbaie afhanklik maak van die temperatuur in die mantel wig. Ons stel voor dat afkoeling van die boonste mantel met slegs 'n klein hoeveelheid gedurende die laat Argeïese, die water-vloeiing smelting van die blad beëindig. Dit het toegelaat dat die blad water in die wig migreer en intermediêre samestelling magmatisme produseer wat sedert geassosieer word met subduksie sones.

Les processus de subduction sont une étape clé de la formation des orogènes et induisent un métamorphisme de haute pression, localisé dans les faciès des schistes bleus et éclogites. Caractériser la durée et l’intensité de ce métamorphisme est ainsi une étape cruciale puisque amenant des contraintes quantitatives sur la géodynamique d’un orogène. Par une étude pétrologique et géochronologique, cette thèse a ainsi pour objectif de préciser les conditions et durées du métamorphisme de haute pression dans le sud du Massif Central Français (chaîne Varisque), à travers l’étude des massifs de Najac, de la Montagne Noire et du Lévézou. Cette thèse associe ainsi une géochronologie multiméthodes (U-Pb sur zircon, rutile et apatite, Lu-Hf et Sm-Nd sur grenat, 40Ar-39Ar sur biotite et muscovite) à des analyses pétrologiques impliquant des modélisations numériques d’équilibres de phases (Theriak-Domino et THERMOCALC). L’étude d’une éclogite du massif de Najac a ainsi permis de déterminer des conditions de 15 à 20 kbar et 560 à 630°C pour le métamorphisme de haute pression. Le début du faciès éclogite y est daté à ~383 Ma, tandis que le pic du métamorphisme éclogitique est atteint à 375.7 ± 1.2 Ma. La datation des éclogites de la Montagne Noire n’a pas permis de préciser un âge solide de l’évènement de haute pression. Néanmoins, les conditions de pression et température du faciès éclogite y sont estimées à ~ 21 kbar et ~ 750°C. L’étude des massifs de Najac et de la Montagne Noire a mis en évidence de potentiels découplages entre les systèmes de terres rares et le système isotopique U-Pb. Les protolithes des terrains éclogitiques du massif du Lévézou, tant mafiques que felsiques, se sont mis en place à ca. 470 Ma. Le métamorphisme éclogitique affectant les roches mafiques est estimé à 21-23 kbar pour 680- 800°C et atteint à ~358 Ma. L’exhumation, bien caractérisée, y est rapide : les terrains éclogitiques atteignent 8-9.5 kbar et ~600°C à ~352 Ma, impliquant une exhumation très rapide, suivie d’un refroidissement de plus de 50°C/Ma. Les granites du massif du Lévézou présentent des pseudomorphoses de cordiérite à disthène-grenat-muscovite-quartz, développées lors du métamorphisme de haute pression et équilibrées à ca. 15-17 kbar et ~670°C. La déformation majeure observée dans ces granites peut s’accompagner de fusion localisée, et semble se produire en différentes étapes, depuis ~352 Ma à ~340 Ma. Replacées dans un contexte général, ces données s’inscrivent pleinement dans les gammes d’âges de la haute pression décrites pour la chaîne varisque et permettent de reconsidérer la tectonique du Massif Central. / Subduction is one of the key stages of the mountain building processes. It leads to the development of high-pressure (HP) metamorphism in the rocks that typically equilibrate in the blueschist or eclogite-facies conditions. Dating the HP metamorphism and estimating its intensity is therefore a major challenge when reconstructing geodynamics through time. Through a petrological and geochronological study, this PhD dissertation aims to better constrain conditions, durations and timings of HP metamorphism in the southern French Massif Central (European Variscan Belt). The massifs of Najac, Montagne Noire and Lévézou were investigated by a multi-method geochronological approach (zircon, rutile and apatite U-Pb dating, garnet Lu-Hf and Sm-Nd dating, biotite and muscovite 40Ar-39Ar dating) associated with a petrological analysis including numerical modelling of phase equilibria (Theriak-Domino and THERMOCALC). The Najac eclogites reached 560-630 °C at 15-20 kbar and the prograde part of the highpressure metamorphic event lasted for ~ 7 Myr starting at ~ 383 and peaking at ~ 376 Ma. Eclogites hosted in sillimanite-bearing migmatites in the Montagne Noire dome (French Massif Central) reached c. 750°C, 21 kbar before significant decompression at high temperatures. However, none of the obtained geochronological dates could be associated with the HP event. The study of the Najac massif and the Montagne Noire Dome highlight potential decoupling between the REE and the U-Pb isotopic systems. The emplacement of the protoliths of felsic and mafic HP rocks in the Lévézou Massif was estimated at ca. 470 Ma. HP metamorphism peaked at 21-23 kbar and 680-800°C at ~358 Ma. The subsequent fast exhumation reached 8-9.5 kbar and ~600°C at ~352 Ma, highlighting a very fast exhumation followed by a cooling rate of 50°C/Ma. Granites from the Lévézou massif display kyanite-garnet-muscovite-quartz pseudomorphs after cordierite that equilibrated at ca. 15-17 kbar and ~670°C. The major deformation in these granites is associated with the exhumation stage, locally accompanied by partial melting, and seems to occur in different episodes, from ~352 Ma to ~340 Ma. On a larger scale, these results are fully in line with the HP ages described in the Variscan Belt and allow to reconsider the tectonics in the French Massif Central.

Exhumation of high-pressure and ultrahigh-pressure eclogites in large orogens and associated petrological change during the process remain enigmatic problems. This dissertation examines eclogites from high-pressure (HP) and ultrahigh-pressure (UHP) terranes in the North-East Greenland Eclogite Province, aiming to decipher their metamorphic pressure-temperature (P-T) paths, evaluate spatial variation of P-T paths, and understand petrological changes during the exhumation. Kyanite-bearing UHP eclogites from North-East Greenland contain a peak mineral assemblage of phengite, garnet, omphacite, kyanite, coesite, rutile and probably epidote-group minerals. Thermodynamic modeling with an XRF-derived bulk composition yielded a peak P-T condition of 3.4 GPa and 920 °C. Petrographic textures, such as graphic intergrowth of amphibole and plagioclase, cusps of plagioclase into garnet and quartz, and neoblasts of garnet indicate that the eclogites were partially melted through dehydration melting of phengite and epidote-group minerals. Since thermodynamic modeling could not yield a satisfactory solidus curve, experimental phase relations were considered in interpreting the melting process, and show a near isothermal decompression path across the epidote mineral melting curve. Additional thermodynamic modeling of a symplectite after omphacite, consisting of amphibole, plagioclase and clinopyroxene, yields a P-T condition of ~ 1.2 GPa and 800 °C. Thermodynamic modeling of a melt pocket yields a further P-T constraint of 1.4 GPa and 740 °C. The HP zoisite eclogites from the Storstrømmen shear zone in the Sanddal area preserve partial melting textures both in garnet and in the matrix. The textures include multiphase solid inclusions of albite and K-feldspar in garnet, graphic intergrowth of amphibole and plagioclase, cuspate textures, and leucosome. Thermodynamic modeling combined with mineral composition and modes yielded an exhumation P-T path from subsolidus conditions at ~1.95 GPa and ~670 °C, to ~1.85 GPa and 715 °C at suprasolidus, to ~1.45 GPa and 640 °C. Paragonite, phengite, and amphibole were the major dehydration melted phases along the exhumation path. The HP kyanite eclogite from the Danmarkshavn area contains disequilibrium textures developed during retrograde stages. Petrographic observation documents two groups of textures: a strongly zoned plagioclase (anorthite to andesine) enclosing a poorly developed symplectite of sapphirine + spinel + plagioclase after kyanite, and a less zoned plagioclase (labradorite to andesine) enclosing a fully developed symplectite after kyanite. Thermodynamic modeling of the bulk rock returns a peak P-T condition of 1.9 GPa and 840 °C. Thermodynamic modeling of a symplectite domain yields poor P-T constraints of 0.8 – 1.3 GPa and 700 – 900 °C. Modeling also indicates the plagioclase development would be richer in Ca during decompression while progressive replacement of kyanite induced the plagioclase rim to be less Ca-rich. This study reveals that HP and UHP eclogites may experience partial melting on their exhumation path. Dehydration melting of hydrous minerals (e.g. phengite and zoisite) is the most plausible way in partially melt the eclogites, because of limited amounts of free fluid. The partial melting does not trigger exhumation of the eclogites, but may facilitate the exhumation process. The near-isothermal exhumation path for the UHP terranes suggests that it was initially exhumed through vertical extrusion. Lateral extrusion by the Storstrømmen and Germania Land shear zones is suggested to have further exhumed the HP and UHP rocks, which is analogous to the lateral escape tectonics in the Tibetan Plateau