Thermochronology; applications to tectonics, petrology, and stratigraphy

Sutter, John F.; Zeitler, Peter K.; Tucker, Robert D.

doi:10.3133/ofr91565

Cited by 3 publications

(1 citation statement)

References 107 publications

(108 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Eclogite formation in North-East Greenland appears to be broadly synchronous with eclogite formation in the Scandinavian Caledonides. The Sm-Nd mineral ages for Greenland samples are Palaeozoic (R. K. Brueckner, personal communication), and essentiaIly comparable to Sm-Nd mineral isochron ages of 447-400 Ma (Griffin & Brueckner, 1980Mørk & Mearns, 1986) and the U-Pb zircon ages of c. 400 Ma (Gebauer et al, 1985;Sutter et al, 1991) for eclogitic rocks in the Western Gneiss Region of Norway. Palaeozoic medium-temperature eclogites are also found in Spitsbergen (Peucat et al, 1989), though their age is not well-constrained.…”

Section: Discussionmentioning

confidence: 78%

Eclogites and related high-pressure rocks from North-East Greenland

Gilotti¹

1994

rapggu

View full text Add to dashboard Cite

Eclogite, gamet clinopyroxenite, gamet websterite and websterite bodies were discovered within the Skærfjorden gneiss complex during recent mapping in North-East Greenland. These eclogitic pods extend from Danmarkshavn (c. 76° 40'N) to the northern limit of the area mapped (78°N), and attest to widespread high-pressure metamorphism. Eclogites with the assemblage omphacite + garnet ± quartz ± futile are common. The protoliths of some of the eclogites were xenoliths within the precursor batholiths to the gneisses. Field relations, regional correlations and preliminary geochronology indicate that the eclogite facies metamorphism is Caledonian. The eclogites formed at minimum pressures between 10-15 kilobars and temperatures between 600–900°C, and hence are the medium-temperature type typically formed in over-thickened crust during continent collision.

show abstract

Section: Discussionmentioning

confidence: 78%

Eclogites and related high-pressure rocks from North-East Greenland

Gilotti¹

1994

rapggu

View full text Add to dashboard Cite

show abstract

Brunswick subduction complex in the Canadian Appalachians: Record of the Late Ordovician to Late Silurian collision between Laurentia and the Gander margin of Avalon

Staal¹

1994

Tectonics

167

119

View full text Add to dashboard Cite

The Brunswick subduction complex in the New Brunswick part of the Canadian Appalachians records the Late Ordovician to Late Silurian collision between Laurentia and the Gander margin of Avalon. The Brunswick complex is anomalously well preserved compared with equivalent rocks and structures elsewhere owing to its unique position in the deepest part of the Quebec reentrant of the Laurentian margin. This part of the margin experienced less underthrusting and exhumation and overprinting by orogen-parallel faulting than the adjacent promontories where collision started earlier. The early, southeast to east vetgent thrust-related structures represent a progressive D 1 deformation that formed in response to northwestward subduction of the previously extended Gander margin and subsequent tectonic unroofing of the subduction complex. The original, shallow northwestward dipping envelope to S 1 was deformed in the Late Silurian by D 2 upright folds and associated shear zones into a steep belt during terminal collision. The D 2 structures probably formed in response to sinistral transpression. Together, D 1 and D 2 indicate that convergence was oblique and sinistral. Most rocks incorporated in the subduction complex formed in the Tetagouche back arc basin that evolved from rifting of an Arenig magmatic arc built on the Gander margin into a wide marginal basin. Subduction was initiated in the Late Ordovician (=455 Ma) in the back arc basin following collision of the Middle Ordovician Popelogan arc with Laurentia in the Caradoc, shortly after its opening in the late Arenig (--473 Ma). The closure history of the Iapetus Ocean involved more than one subduction zone and arc-continent collision and rivals the southwestern Pacific Ocean in its complexities. IntroductionAlthough it is generally accepted that plate tectonic processes were responsible for the formation of the Appalachian-Caledonian Orogen, few subduction or accretionary complexes have been identified or documented. The ophiolitic melanges in western Newfoundland [e.g., Williams, 1975Williams, , 1977 are the remnants of a westward facing subduction complex that records the oblique collision between the Notre Dame arc (approximately the western part of Dunnage bounded by the Red Indian Line (RIL) to the east Paper number 93TC03604. 0278-7407/94/93TC-03604510.00 in inset of Figure 1) and Laurentia in the Early to Middle Ordovician [Cawood and Suhr, 1992]. Sparce Laurentian fossils in Early to Middle Ordovician sedimentary rocks are mixed with volcanic rocks of the Notre Dame arc, whereas peri-Gondwanan faunas (trilobites and brachiopods) occur in Middle Ordovician sediments that overstep the Early Ordovician ophiolites in the eastern part of the Dunnage Zone (Exploits Subzone of Williams et al. [1988]) and rocks of the Gander Zone [Nowlan and Thurlow, 1984; Neuman, 1984; van Staal and Williams, 1991; Williams et al., 1992]. The volcanic rocks of the Notre Dame arc, in contrast to coeval arc volcanic rocks occurring in the Exploits Subzone (east of RIL in inset of Figur...

show abstract