Orogenic paleofluid flow recorded by discordant detrital zircons in the Caledonian foreland basin of northern Greenland

Morris, G. A.; Kirkland, Christopher L.; Pease, Victoria

doi:10.1130/l420.1

Cited by 19 publications

(12 citation statements)

References 37 publications

(35 reference statements)

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“…It has long been recognized that detrital zircon from metaclastic rocks yields a high proportion of discordant zircon due to postdeposition metamorphism (e.g., Gehrels et al, 1991). Other studies have demonstrated that a high number of discordant analyses may be due to postdeposition alteration (e.g., Morris et al, 2015). In contrast, the high degree of discordance in this study (~40%) reflects the metamorphic character of the source terrane rather than postdepositional processes.…”

Section: Characteristic Signature Of Detrital Zircon From Metamorphiccontrasting

confidence: 64%

Carboniferous basin in Holm Land records local exhumation of the North-East Greenland Caledonides: Implications for the detrital zircon signature of a collisional orogen

et al. 2016

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Carboniferous strata of the Wandel Sea Basin unconformably overlie the Laurentian Precambrian crystalline rocks of the Caledonian hinterland at its northernmost exposures in Holm Land (~80°N). Complex zircon from an intermediate gneiss gives an upper-intercept age of 1878 ± 71 Ma, a protolith age which fits with the regional 1.8-2.0 Ga calc-alkaline arc. A strongly deformed pegmatite was intruded at 435 ± 17 Ma, and it is a rare example of Caledonian magmatism in the northern sector of the orogen. Omphacite confirms the presence of eclogite (sensu stricto) lenses in the basement complex, thus documenting the northern extent of the NorthEast Greenland eclogite province formed during the Caledonian collision with Baltica. Holm Land lies in the eastern block of the eclogite province, where an ultrahigh-pressure (UHP) meta morphic event took place at 365-350 Ma. Zircon from a Holm Land eclogite lacks a Eu anomaly, has a flat heavy rare earth element pattern, and gives a sensitive high-resolution ion microprobe U-Pb age of 423 ± 7 Ma, and it is thus interpreted as the time of high-pressure (HP) metamorphism. This age overlaps with the established age of widespread HP metamorphism for the eclogite province (i.e., 415-395 Ma), rather than the younger UHP metamorphism. Westward thrusting of the NorthEast Greenland eclogite province onto the Laurentian margin after 395 Ma and subsequent exhumation of this uppermost thrust sheet provided a substrate for Carboniferous deposition. Detrital zircon age spectra from arkosic sandstones of the late Viséan (ca. 330-340 Ma) Sortebakker and early Moscovian (ca. 310-315 Ma) Kap Jungersen Formations record the progressive unroofing of the NorthEast Greenland Caledonides. All seven samples have a major peak at 1.8-2.0 Ga, and five also have a 1.75 Ga peak, matching the Paleoproterozoic arc and later anorogenic granitoids that comprise the crystalline basement. Paleozoic grains are sparse in the Sortebakker sandstones, but they constitute a pronounced 400 Ma peak in the younger Kap Jungersen Formation. The composition of the detritusincluding garnet clasts, the high amount of discordant zircon (40%), and the large numbers of grains with metamorphic rims that cluster around 410 Ma-reflects a local provenance sourced in the NorthEast Greenland eclogite province, with some input from the overlying thrust sheets. Other Devonian and Carboniferous basins within and peripheral to the Caledonides also show distinct signatures, demonstrating that there is not a simple, representative detrital zircon signature for the Caledonian orogen.

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Section: Characteristic Signature Of Detrital Zircon From Metamorphiccontrasting

confidence: 64%

Carboniferous basin in Holm Land records local exhumation of the North-East Greenland Caledonides: Implications for the detrital zircon signature of a collisional orogen

et al. 2016

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“…To better understand the most likely timing of radiogenic-Pb loss we model the discordant age data from sample BB5 using a variety of times of assumed Pb loss, with the resultant population compared with concordant data using the K-S statistic following the approach discussed by Morris et al (2015). The approach assumes that the discordant population is derived from a similar geological province with similar zircon age spectra to the concordant zircon population.…”

Section: Discordant Age Datamentioning

confidence: 99%

The source of Dalradian detritus in the Buchan Block, NE Scotland: application of new tools to detrital datasets

Johnson

Kirkland

Reddy

et al. 2016

JGS

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Detrital zircons from four samples of upper Dalradian metasedimentary rocks from the Buchan Block in the NE Grampian Highlands of Scotland were analysed by laser ablation inductively coupled plasma mass spectrometry to establish their U-Pb age and trace element composition. The analysed grains (magmatic cores) mainly yield concordant ages ranging from Neoproterozoic to Eoarchaean. Kernel density plots of the data show pronounced peaks in the late Mesoproterozoic, Palaeoproterozoic and Neoarchaean eras. The data are indistinguishable from detrital zircon age spectra from Dalradian rocks elsewhere, an interpretation supported by application of a non-parametric multidimensional scaling algorithm, and are consistent with a Laurentian source. Similar to existing studies from other Dalradian rocks, the age spectra from the Buchan Block reveal an increase in the relative proportion of older detritus with time, suggesting derivation from late Mesoproterozoic (Grenville) then Palaeoproterozoic orogens before widespread exposure and denudation of their Archaean basement rocks. Application of a novel approach to estimate the most likely time of radiogenic-Pb loss indicates that some detrital zircon grains were affected by element mobility around 470-450 Ma as a result of Grampian orogenesis.Supplementary material: Laser ablation inductively coupled plasma mass spectrometry U-Pb and trace element data, a matrix showing results of Kolmogorov-Smirnov (K-S) test, cathodoluminescence imaging of zircons and selected trace element plots are available at https://doi.

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“…How to handle discordance in detrital zircon data is beyond the scope of the present study, but the problem has been discussed in recent papers by Morris et al . () and Reimink et al . ().…”

Section: Discussionmentioning

confidence: 88%

Visualizing, interpreting and comparing detrital zircon age and Hf isotope data in basin analysis – a graphical approach

2017

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The development of fast and reliable instrumental methods for U-Pb dating and Lu-Hf isotope analysis of zircon has caused detrital zircon to become a popular provenance indicator for clastic sediments and an important tool in basin analysis. In parallel with the increasing ease of access to data, advanced methods of data interpretation have been developed. The downside of some techniques for visualization and comparison of detrital zircon distribution patterns is that the results are difficult to relate to what the zircon grains really record: The age and nature of geological processes in a protosource terrane. Some simple methods of data presentation and inter-sample comparison that preserve a direct and intuitively understandable relationship between the data and the age of zirconforming processes in the protosource are proposed here: Comparison of confidence intervals around empirical, cumulative distribution curves combined with the use of a plot of upper vs. lower quartile values of cumulative zircon U-Pb age or Lu-Hf model age distributions. This approach allows a robust and transparent separation to be made between samples whose detrital zircon distributions are indistinguishable from each other, and those that are more or less similar. Furthermore, it allows simple comparison between detrital zircon distributions and the geological age record of potential protosource terranes, or the detrital zircon distributions of possible sedimentary precursors.

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Orogenic paleofluid flow recorded by discordant detrital zircons in the Caledonian foreland basin of northern Greenland

Cited by 19 publications

References 37 publications

Carboniferous basin in Holm Land records local exhumation of the North-East Greenland Caledonides: Implications for the detrital zircon signature of a collisional orogen

Carboniferous basin in Holm Land records local exhumation of the North-East Greenland Caledonides: Implications for the detrital zircon signature of a collisional orogen

The source of Dalradian detritus in the Buchan Block, NE Scotland: application of new tools to detrital datasets

Visualizing, interpreting and comparing detrital zircon age and Hf isotope data in basin analysis – a graphical approach

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