The role of East Greenland as a source of sediment to the Vøring Basin during the Late Cretaceous

Provenance-sensitive heavy mineral criteria, mineral chemistry and detrital zircon age data show that there are strong links between Cretaceous sandstones in the Voring Basin and East Greenland areas. There are marked differences in the age spectra of detrital zircons from wells along the eastern margin of the Voring Basin (sandstone type K1) and those in the centre and west of the basin (sandstone type K2). K1 sandstones have a relatively simple zircon age spectra age with largely Mid-Late Proterozoic zircons and a number of Caledonian age zircons. By contrast, K2 sandstones have complex zircon age spectra, with Archaean, Early Proterozoic, Permo-Triassic and mid-Cretaceous age zircons that are absent in K1 sandstones. Some sandstones of Cenomanian and younger age from East Greeland share mineralogical features with the K2 sandstone type, having overlapping ranges of critical provenance sensitive paramenters such as RuZi, MZi and CZi, and similar types of detrital tourmalines and garnets. Detrital zircon age spectra from East Greenland samples include critical Archaean, Early Proterozoic and Permo-Triassic populations found in K2 sandstones. The zircon age data therefore provide support for sourcing of K2 sandstones from East Greenland. However, a source for the K2 sandstones to the east of the Caledonian front in Scandinavia cannot be ruled out, neither can recycling of older sediment previously transferred across the rift

The role of East Greenland as a source of sediment to the Vøring Basin during the Late Cretaceous

Provenance-sensitive heavy mineral criteria, mineral chemistry and detrital zircon age data show that there are strong links between Cretaceous sandstones in the Voring Basin and East Greenland areas. There are marked differences in the age spectra of detrital zircons from wells along the eastern margin of the Voring Basin (sandstone type K1) and those in the centre and west of the basin (sandstone type K2). K1 sandstones have a relatively simple zircon age spectra age with largely Mid-Late Proterozoic zircons and a number of Caledonian age zircons. By contrast, K2 sandstones have complex zircon age spectra, with Archaean, Early Proterozoic, Permo-Triassic and mid-Cretaceous age zircons that are absent in K1 sandstones. Some sandstones of Cenomanian and younger age from East Greeland share mineralogical features with the K2 sandstone type, having overlapping ranges of critical provenance sensitive paramenters such as RuZi, MZi and CZi, and similar types of detrital tourmalines and garnets. Detrital zircon age spectra from East Greenland samples include critical Archaean, Early Proterozoic and Permo-Triassic populations found in K2 sandstones. The zircon age data therefore provide support for sourcing of K2 sandstones from East Greenland. However, a source for the K2 sandstones to the east of the Caledonian front in Scandinavia cannot be ruled out, neither can recycling of older sediment previously transferred across the rift

Precise U–Pb Baddeleyite Dating of the Derim Derim Dolerite, McArthur Basin, Northern Territory: Old and New SHRIMP and ID-TIMS Constraints

The Mesoproterozoic Roper Group of the McArthur Basin has excellent petroleum potential, but exploration has been hampered by poor constraints on its post-depositional history that has compromised understanding of the tectonostratigraphic evolution of the basin. The Derim Derim Dolerite occupies an important position in the event chronology of the McArthur Basin, having intruded the Roper Group prior to post-Roper basin inversion, and it is also a major component of Mesoproterozoic intraplate mafic magmatism in northern Australia. Since 1997, the Derim Derim Dolerite has been assigned a magmatic crystallisation age of 1324 ± 4 Ma (all uncertainties are 95% confidence), based on unpublished sensitive high-resolution ion micro probe (SHRIMP) U–Pb analyses on baddeleyite attributed to a dolerite sample from Bureau of Mineral Resources drill-hole Urapunga 5. Herein, we establish that the SHRIMP sample originated from the type locality of the Derim Derim Dolerite in outcrop 90 km northwest of Urapunga 5 and document the 207Pb/206Pb date interpreted from the 1997 dataset. New U–Pb SHRIMP reanalysis of the same grain-mounts yielded a mean 207Pb/206Pb date of 1320.1 ± 5.3 Ma, confirming the 1997 result, and isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) analysis of baddeleyites plucked from the mounts yielded a precise mean 207Pb/206Pb date of 1327.5 ± 0.6 Ma. This date is significantly older than a baddeleyite U–Pb ID-TIMS date of ca 1313 Ma recently reported elsewhere from dolerite in the Beetaloo Sub-basin 200 km to the south, indicating that magmatism attributed to the Derim Derim Dolerite spanned at least 10–15 Ma. Previously documented geochemical variation in Mesoproterozoic intraplate mafic rocks across the Northern Territory (such as the 1325 ± 36 Ma Galiwinku Dolerite in the McArthur Basin, 1316 ± 40 Ma phonolites in the Nimbuwah Domain of the eastern Pine Creek Orogen, and 1295 ± 14 Ma gabbro in the Tomkinson Province) may reflect episodic pulses of magmatism hitherto obscured by the low precision of the available isotopic dates. The timing and geochemistry of Derim Derim-Galiwinku mafic igneous activity is strikingly similar to that of the Yanliao Large Igneous Province (LIP) in the northern North China Craton, and the global paucity of 1330–1300 Ma LIPs suggests that the North Australian Craton and the North China Craton were in relatively close proximity at that time

Recognition of c. 1780 Ma magmatism and metamorphism in the buried northeastern Gawler Craton: Correlations with events of the Aileron Province

The far northeastern Gawler Craton, South Australia, lies at the northern margin of one of the major building blocks of the Australian continent and is a region that is important in models for the Proterozoic tectonic evolution of Australia. However, this region is overlain by Phanerozoic sedimentary cover and consequently has had no previous geological study. We report the lithotypes, geochronology, geochemistry and isotopic composition of rocks recovered in a mineral exploration drill hole in the far northeastern Gawler Craton, the sole drill hole to sample crystalline basement in this region. Lithologies within the drill hole are garnet- and pyrite-bearing metasedimentary gneiss, pyroxenite and gabbroic intrusions, along with granitic bodies. Metasedimentary gneiss has a maximum depositional age of 1841 ± 4 Ma and a provenance pattern more similar to rocks of the Aileron Province of the Arunta Region, central Australia, in particular the Lander Rock Formation, than to other metasedimentary rocks of the Gawler Craton. Amphibolite facies metamorphism occurred at c. 1780 Ma and was synchronous with emplacement of high Mg, crustally contaminated mafic rocks, along with several types of felsic intrusion. This metamorphic event is very similar in age and style to the Yambah Event of the Aileron Province, and has not been documented previously in the Gawler Craton. The overall geological features of this portion of the northern Gawler Craton support models that link it with the Aileron Province of the Arunta Region. The rocks of drill hole TB02 underwent thermal resetting recorded by a biotite 40Ar/39Ar age of c. 480 Ma, likely as a result of the Cambro-Ordovician Delamerian Orogeny along the eastern margin of Gondwana