scholarly journals Ocean Drilling Program (ODP) off South-East Greenland: formation of a volcanic rifted margin

1993 ◽  
Vol 159 ◽  
pp. 69-73
Author(s):  
H.C Larsen
Keyword(s):  
Continental Shelf ◽  
Tectonic Setting ◽  
Igneous Rocks ◽  
Plate Tectonic ◽  
Ocean Drilling Program ◽  
Skaergaard Intrusion ◽  
East Greenland ◽  
Ocean Drilling ◽  
Magmatic Rocks ◽  
Rifted Margin

The exposures of the Tertiary igneous rocks along the East Greenland coast (Fig. I) have attracted the attention or earth scientists for more than half a century (Wager, 1934; Wager & Deer 1938). However, most of the work has concentrated on the petrological and mineralogical aspects of the magmatic rocks (e.g. Skaergaard intrusion). With a few exceptions, such as Brooks (1973). Nielsen (1978). H. C. Larsen (1978), Branks (1979), Myers (1980) and Nielsen & Branks (1981). Relatively little attention has been given to the tectonic and plate tectonic setting. mainly because the plate tectonic paradigm did not become accepted until 30 years after Wager and Deer's revolutionary work. Furthermore, the tectonic context of the coastal exposures first becomes really striking when seen together with the geology and structure of the adjacent continental shelf and slope (H.C. Larsen, 1990).

scholarly journals The Danish Lithosphere Centre in 1995

1996 ◽  
Vol 172 ◽  
pp. 85-87
Author(s):  
H.C Larsen
Keyword(s):  
Continental Shelf ◽  
Offshore Drilling ◽  
Ocean Drilling Program ◽  
East Greenland ◽  
Major Field ◽  
Preliminary Results ◽  
Ocean Drilling ◽  
Drilling Operations ◽  
Aims And Scope

The Danish Lithosphere Centre (DLC) is funded by the Danish National Research Foundation and was established in 1994 (Larsen, 1995). In 1995 DLC undertook major field geological investigations in both West and East Greenland, and within the Ocean Drilling Program (ODP) drilling on the continental shelf offshore East Greenland. More than 50 national and international researchers were involved in DLC field geological programmes, and 25 researchers from ODP member countries took part in the offshore drilling operations. The general aims and scope of these activities as well as the continued development of the Centre are summarised below. Preliminary results of the 1995 work programmes are given by van Gool et al., Larsen et al. and Brooks et al. (all this report).

Rift propagation north of Iceland: A case of asymmetric plume - rift interaction?

2020 ◽  
Author(s):  
Hans Christian Larsen ◽  
Anett Blischke ◽  
Bryndís Brandsdóttir ◽  
Keyword(s):  
Ocean Drilling Program ◽  
East Greenland ◽  
Ocean Drilling ◽  
North East ◽  
Rifted Margins ◽  
Rift Propagation ◽  
Melt Distribution ◽  
Convolution Process ◽  
Iceland Plume ◽  
Greenland Margin

<p>Drilling by the Ocean drilling Program (ODP Legs 104, 152, 163) and geophysical studies have inferred a widespread and strong influence by the Iceland plume on the structure of the ~2500 km long volcanic rifted margins that formed between East Greenland and NW Europe during continental breakupat  ~56-54 Ma. A persistent, but spatially much reduced impact by the plume on crustal structure is evident along the ~250 km Greenland-Iceland-Faeroe ridge (GIFR). Spreading south of the GIFR has remained comparatively stable along the Reykjanes Ridge (RR). By contrast, spreading between the GIFR and northwards to the Jan Mayen Fracture Zone (JMFZ) involved northward rift propagation (~50-25 Ma) away from the Iceland plume and into the East Greenland margin. This was paired with a northward retreat of the initial spreading axis (Aegir ridge (AER)) further to the east. Slivers of the East Greenland continental crust topped by continental plateau basalts extruded during initial breakup were torn off by this northward rift propagation, and form segments of the Jan Mayen microcontinent (JMMC). Rift propagation resulted in the formation of the Iceland Plateau (IP) underlain by anomalously thick and shallow oceanic crust. The striking asymmetry in plate kinematics and crustal structures south and north of Iceland seems associated with a less enriched mantle source feeding the spreading system north of Iceland. This suggests a potentially long-lived north-south asymmetry in the composition and dynamics of the plume that, if confirmed, will favor the existence of distinctly different mantle reservoirs rather than a mixing (entrainment) process followed by a compositional de-convolution process during decompression melting and melt distribution. IODP proposal 976-Pre will address these topics by investigating the temporal and compositional development of the crust of the IP, as well as the transition from rift propagation by the IP rift (IPR) into the present day Kolbeinsey ridge (KR). Drilling will sample 2-3 stages of four IPR propagation stages we have mapped, the transition from the IPR to KR spreading, rifting and timing of transpressive movements along the pseudo-transform zone that linked the propagating IPR to the retreating AER. One drill site hopefully will establish the stratigraphic relationship between the JMMC basalts and the East Greenland plateau basalts. Sediment cover at the drill sites will constrain subsidence history and the paleo-environmental evolution of the high-latitude north-east Atlantic and its connectivity to the global ocean.The proposed drilling addresses long-standing ocean drilling themes of continental breakup, rift propagation, mantle plume reservoirs and structure, and north Atlantic paleoceanography.</p>

scholarly journals Burial and exhumation history of the Jameson Land Basin, East Greenland, estimated from thermochronological data from the Blokelv-1 core

2018 ◽  
pp. 133-147
Author(s):  
Paul F. Green ◽  
Peter Japsen
Keyword(s):  
Middle Eocene ◽  
Vitrinite Reflectance ◽  
Upper Jurassic ◽  
Late Eocene ◽  
Early Eocene ◽  
Ocean Drilling Program ◽  
East Greenland ◽  
Ocean Drilling ◽  
History Of ◽  
Intrusive Activity

Apatite fission-track analysis (AFTA) data in two Upper Jurassic core samples from the 231 m deep Blokelv-1 borehole, Jameson Land, East Greenland, combined with vitrinite reflectance data and regional AFTA data, define three palaeo-thermal episodes. We interpret localised early Eocene (55– 50 Ma) palaeotemperatures as representing localised early Eocene heating related to intrusive activity whereas we interpret late Eocene (40–35 Ma) and late Miocene (c. 10 Ma) palaeotemperatures as representing deeper burial followed by successive episodes of exhumation. For a palaeogeothermal gradient of 30°C/km and likely palaeo-surface temperatures, the late Eocene palaeotemperatures require that the Upper Jurassic marine section in the borehole was buried below a 2750 m thick cover of Upper Jurassic – Eocene rocks prior to the onset of late Eocene exhumation. As these sediments are now near outcrop at c. 200 m above sea level, they have been uplifted by at least 3 km since maximum burial during post-rift thermal subsidence. The results are consistent with estimates of rock uplift on Milne Land since the late Eocene and with interpretation of Ocean Drilling Program (ODP) data off South-East Greenland suggesting that mid-Cenozoic uplift of the margin triggered the marked influx of coarse clastic turbidites during the late Oligocene above a middle Eocene to upper Oligocene hiatus.

Petrography and geochemistry of feldspathic and mafic sediments of the northeastern Pacific margin

1985 ◽  
Vol 76 (4) ◽  
pp. 411-449 ◽  
Author(s):  
Peter C. van de Kamp ◽  
Bernard Elgey Leake
Keyword(s):  
Sierra Nevada ◽  
Tectonic Setting ◽  
Potassium Feldspar ◽  
Igneous Rocks ◽  
Plate Tectonic ◽  
Late Mesozoic ◽  
Chemical Signatures ◽  
Clastic Sediments ◽  
Northeastern Pacific ◽  
Pacific Margin

ABSTRACTThis study attempts to ascertain whether the differing provenance sources and plate tectonic settings of deposition of clastic sediments and rocks can be identified by chemical means, thus opening the increased use of these rocks and their metamorphosed derivatives in plate tectonic modelling. Mineralogically immature feldspathic and mafic sands, muds, sandstones and shales from Mesozoic, Cenozoic and Holocene clastic deposits in California, Oregon, Alaska and Colorado have been both modally and chemically analysed providing a valuable data base (217 samples; 216 samples chemically analysed, many for 28 elements).There is significant upward chemical variation in the Great Valley sequence of California which mimics previously described petrographic variation and in turn reflects provenance changes with igneous episodes and erosional stripping of the Sierra Nevada in late Mesozoic time. Differing sandstone petrofacies result in varying chemical signatures and while the provenances of monomict sediments are easiest to identify, polymict sources involving granitoid or ophiolitic material can often be identified by potassium feldspar or Cr contents. The distinction of K which is derived from detrital potassium feldspar from K derived from detrital illite, micas or other sheet minerals, is best made by a Niggli al–alk plot against k. Mafic sandstones derived from mafic volcanic or plutonic rocks preserve essentially mafic igneous chemistry and could be possible parent sources of some amphibolites which grade into metasediments. The lithified erosion products of the Sierra Nevada calc-alkaline igneous rocks have higher Niggli al–alk and higher average Niggli si at any given mg value than the fresh igneous rocks enabling meta-arkoses to be distinguished from meta-igneous rocks.Applying previously published chemical criteria gives the actual plate tectonic setting of deposition of most of the sandstones studied. This suggests that the chemical composition of sandstones can yield much more information about the provenance and plate tectonic setting than hitherto recognised.

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