Metamorphic pressure-temperature paths of eclogites from The North-East Greenland Caledonides

2016 ◽  
Author(s):  
Wentao Cao
Keyword(s):  
2006 ◽  
Vol 143 (4) ◽  
pp. 431-446 ◽  
Author(s):  
C. SARTINI-RIDEOUT ◽  
J. A. GILOTTI ◽  
W. C. McCLELLAND

The North-East Greenland eclogite province is divided into a western, central and eastern block by the sinistral Storstrømmen shear zone in the west and the dextral Germania Land deformation zone in the east. A family of steep, NNW-striking dextral mylonite zones in the Danmarkshavn area are geometrically and kinematically similar to the ductile Germania Land deformation zone, located 25 km to the east. Amphibolite facies deformation at Danmarkshavn is characterized by boudinage of eclogite bodies within quartzofeldspathic host gneisses, pegmatite emplacement into the boudin necks and subsequent deformation of pegmatites parallel to gneissosity, a widespread component of dextral shear within the gneisses, and localization of strain into 10–50 m thick dextral mylonite zones. The gneisses and concordant mylonite zones are cut by a swarm of weakly to undeformed, steeply dipping, E–W-striking pegmatitic dykes. Oscillatory-zoned zircon cores from two boudin neck pegmatites give weighted mean 206Pb/238U sensitive, high mass resolution ion microprobe (SHRIMP) ages of 376 ± 5 Ma and 343 ± 7 Ma. Cathodoluminescence images of these zircons reveal complex additional rims, with ages from ranging from c. 360 to 320 Ma. Oscillatory-zoned, prismatic zircons from two late, cross-cutting pegmatites yield weighted mean 206Pb/238U SHRIMP ages of 343 ± 5 Ma and 332 ± 3 Ma. Zircons from the boudin neck pegmatites record a prolonged growth history, marked by fluid influx, during amphibolite facies metamorphism beginning at c. 375 Ma. The cross-cutting pegmatites show that dextral deformation in the gneisses and ductile mylonite zones had stopped by c. 340 Ma. Ultrahigh-pressure metamorphism in the eastern block at 360 Ma requires that the Greenland Caledonides were in an overall contractional plate tectonic regime. This, combined with 20% steep amphibolite facies lineations in the eclogites, gneisses and mylonites suggests that dextral transpression may have been responsible for a first stage of eclogite exhumation between 370 and 340 Ma.


1989 ◽  
Vol 145 ◽  
pp. 90-97
Author(s):  
N Henriksen ◽  
J.D Friderichsen ◽  
R.A Strachan ◽  
N.J Soper ◽  
A.K Higgins

The area between Grandjean Fjord and Bessel Fjord was the focus in 1988 of regional geological investigations and 1:500000 mapping during the North-East Greenland project (Henriksen, 1989). The greater part of the area forms part of the East Greenland Caledonides and can be divided into three distinct rock groups: infracrustal gneisses and granites of possibie Archaean or early Proterozoic origin; a metasedimentary sequence which has probably suffered both mid-Proterozoic and Caledonian migmatisation and metamorphism; and the late Proterozoic Eleonore Bay Group, a thick sedimentary sequence which has undergone amphibolite facies Caledonian metamorphism in its lower parts and is intruded by Caledonian granites. Aspects of the stratigraphy and sedimentology of the Eleonore Bay Group are described by Sønderholm et al. (1989); only the structures affecting the sequence are described here.


Author(s):  
Jørgen A. Bojesen-Koefoed ◽  
Morten Bjerager ◽  
H. Peter Nytoft ◽  
Henrik I. Petersen ◽  
Stefan Piasecki ◽  
...  

The marine, mudstone-dominated Hareelv Formation (Upper Jurassic) of Jameson Land, East Greenland is a representative of the widespread Kimmeridge Clay Formation equivalents, sensu lato, known from the greater North Atlantic region, western Siberia and basins off eastern Canada. These deposits constitute the most important petroleum source-rock succession of the region. The present study reports petroleum geochemical data from the 233.8 m thick succession penetrated by the fully cored Blokelv-1 borehole, and includes supplementary data from outcrop samples and other boreholes in Jameson Land. The succession consists of basinal mudstone intercalated with a significant proportion of gravity-flow sandstones, both in situ and remobilised as injectites. The mudstones are generally rich in organic carbon with values of TOC reaching nearly 19 wt% and high pyrolysis yields reaching values of S2 up to nearly 43 kg HC/ton. Hydrogen Indices are up to 363. The data presented herein demonstrate that weathering of abundant pyritic sulfur adversely affects the petroleum potential of the kerogen in outcrop samples. The succession is thermally immature to early mature, except where intrusions have locally heated adjacent mudstones. The documentation of rich gas/oil-prone Upper Jurassic successions in Jameson Land is important for the assessment of the regional petroleum potential, including the North-East Greenland continental shelf.


2004 ◽  
Vol 5 ◽  
pp. 99-112 ◽  
Author(s):  
Stefan Piasecki ◽  
John H. Callomon ◽  
Lars Stemmerik

The Jurassic of Store Koldewey comprises a Middle Jurassic succession towards the south and an Upper Jurassic succession towards the north. Both successions onlap crystalline basement and coarse sediments dominate. Three main lithostratigraphical units are recognised: the Pelion Formation, including the Spath Plateau Member, the Payer Dal Formation and the Bernbjerg Formation. Rich marine macrofaunas include Boreal ammonites and the successions are dated as Late Bathonian – Early Callovian and Late Oxfordian – Early Kimmeridgian on the basis of new collections combined with material in earlier collections. Fine-grained horizons and units have been analysed for dinoflagellate cysts and the stratigraphy of the diverse and well-preserved flora has been integrated with the Boreal ammonite stratigraphy. The dinoflagellate floras correlate with contemporaneous floras from Milne Land, Jameson Land and Hold with Hope farther to the south in East Greenland, and with Peary Land in North Greenland and Svalbard towards the north. The Middle Jurassic flora shows local variations in East Greenland whereas the Upper Jurassic flora gradually changes northwards in East Greenland. A Boreal flora occurs in Peary Land and Svalbard. The characteristic and stratigraphically important species Perisseiasphaeridium pannosum and Oligosphaeridium patulum have their northernmost occurrence on Store Koldewey, whereas Taeniophora iunctispina and Adnatosphaeridium sp. extend as far north as Peary Land. Assemblages of dinoflagellate cysts are used to characterise significant regional flooding events and extensive sequence stratigraphic units.


2018 ◽  
Vol 37 (1) ◽  
pp. 15-39 ◽  
Author(s):  
Wentao Cao ◽  
Jane A. Gilotti ◽  
Hans-Joachim Massonne ◽  
Simona Ferrando ◽  
Charles T. Foster

2016 ◽  
Author(s):  
Jane A. Gilotti ◽  
◽  
William C. McClelland ◽  
Thejashwini Ramarao ◽  
Lars Stemmerik ◽  
...  

Author(s):  
Henrik Tirsgaard ◽  
Martin Sønderholm

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Tirsgaard, H., & Sønderholm, M. (1997). Lithostratigraphy, sedimentary evolution and sequence stratigraphy of the Upper Proterozoic Lyell Land Group (Eleonore Bay Supergroup) of East and North-East Greenland. Geology of Greenland Survey Bulletin, 178, 1-60. https://doi.org/10.34194/ggub.v179.5076 _______________ The Late Proterozoic Lyell Land Group is an approximately 3 km thick succession of siliciclastic shelf deposits, within the upper part of the Eleonore Bay Supergroup. It is widely exposed in the region between Ardencaple Fjord in the north and Canning Land in the south. In this paper the seven formations named by Sønderholm & Tirsgaard (1993) are formally described. These are from base to top: the Kempe Fjord Formation (400-600 m thick), the Sandertop Formation (200-405 m thick), the Berzelius Bjerg Formation (250-450 m thick), the Kap Alfred Formation (500-640 m thick), the Vibeke Sø Formation (290-325 m thick), the Skjoldungebrae Formation (205-240 m thick) and the Teufelsschloss Formation (35-110 m thick). Five facies associations have been recognised. Outer shelf deposits dominated by dark green, brown to dark red mudstones with thin sandstone lenses are mainly found in the Sandertop, Kap Alfred and Skjoldungebræ Formations. Storm- and wave-dominated inner shelf deposits comprising fine-grained sandstones and dark heterolithic mudstones are common in the Sandertop, Kap Alfred, Vibeke Sø and Skjoldungebrae Formations and are also found in southern outcrops of the Teufelsschloss Formation. Tidally influenced shoreface deposits form stacks of laterally extensive sandstone bodies separated by heterolithic mudstones and are only found in the middle part of the Kap Alfred Formation. Storm- and wave-dominated shoreface deposits comprise highly mature, thick and laterally very extensive sandstone bodies of which a few may be traced for distances exceeding 150 km. This association is present in several intervals within all formations of the Lyell Land Group. Tidally dominated coastal plain deposits consist of stacked sandstone sheets forming laterally extensive, multistorey units separated by heterolithic mudstones and sandstones. These sediments form part of the Kempe Fjord and Berzelius Bjerg Formations and are also found in northern outcrops of the Teufelsschloss Formation. Evidence from palaeocurrent data combined with regional lithological variations suggest a consistent general N-S coastline with the basin deepening in an eastward direction. Deflection of geostrophic currents suggest a palaeolatitude on the southern hemisphere. The deposits of the Lyell Land Group are subdivided into four, large-scale sequences which overall show the same general sedimentary evolution through time reflecting large-scale, cyclic changes in relative sea-level. The sequences vary in thickness from 400-1000 m and are all readily traceable 300 km parallel and 100 km perpendicular to inferred palaeocoastline. The development of all sequences indicates that major regional translation of facies are related to large-scale forced regressions. Sequence stratigraphic considerations suggest that correlation of formations of the Lyell Land Group with units of the Petermann Bjerg Group some 75 km to the west may be very difficult to carry out. Citation: Tirsgaard, H. & Sønderholm, M. 1997: Lithostratigraphy, sedimentary evolution and sequence stratigraphy of the Upper Proterozoic Lyell Land Group (Eleonore Bay Supergroup) of East and North-East Greenland. Geology of Greenland Survey Bulletin 178, 60 pp.


2021 ◽  
Author(s):  
Wentao Cao ◽  
Jane Gilotti ◽  
Hans-Joachim Massonne

<p>Kyanite eclogite from the North-East Greenland Caledonides – the upper plate of the Caledonian orogeny – preserves a mineral assemblage and petrographic texture that are consistent with an initial near-isothermal exhumation path. Two medium-grained kyanite eclogites from the Danmarkshavn area (76°46’N, 18°40’W) located west of the Germania Land shear zone contain the peak assemblage of garnet + omphacite + kyanite + phengite + amphibole + rutile. Subhedral garnet encloses monomineralic omphacite and polymineralic inclusions of clinopyroxene + plagioclase ± quartz ± amphibole ± K-feldspar ± kyanite. X-ray mapping of garnet indicates a homogenous core with a composition of Py<sub>51–52</sub>Alm<sub>28–29</sub>Gr<sub>19–20</sub>Sp<sub>0–1</sub>, along with a slightly zoned rim of Py<sub>54</sub>Alm<sub>31</sub>Gr<sub>15</sub>Sp<sub>1</sub> that is replaced by a corona of symplectitic amphibole + plagioclase. Omphacite (X<sub>Na</sub> up to 0.41), rarely present in the matrix, is indicated by symplectite of clinopyroxene + amphibole + plagioclase. Symplectites of corundum + plagioclase, spinel + plagioclase and sapphirine + plagioclase replace former kyanite. These symplectites are typically surrounded by a plagioclase corona with decreasing Ca (from X<sub>An</sub> = 92–97 to X<sub>An</sub> = 47–53) from the symplectite to the matrix. Isochemical phase equilibrium modeling along with homogenous garnet core and peak omphacite compositions yielded a peak metamorphic pressure-temperature (<em>P-T</em>) condition at 1.9 GPa, 840 ˚C. Assuming local equilibrium at the microscopic scale, an attempt to model a symplectite of spinel + sapphirine + plagioclase after kyanite using a pseudosection yielded estimated <em>P-T</em> conditions at 0.8–1.3 GPa and 700–900 ˚C. Integrating the calculated <em>P-T</em> conditions and previous geochronological results, an initial exhumation path from 1.9 GPa to ~1.0 GPa from ~415–390 Ma to ~375 Ma is nearly isothermal at around 800 ˚C.</p>


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