Uwe Kirscher

Curtin University

Widespread interaction between meteoric (fresh) water and emerged continental crust on the early Earth may have been key to the emergence of life, although when the hydrological cycle first started is poorly constrained. Here we use the oxygen isotopic composition of dated zircon crystals from the Jack Hills, Western Australia, to determine when th...

Although Pangea as Earth’s youngest supercontinent has continuously served as a pivotal reference mark in paleogeographic reconstructions, its assembly is still a matter of debate. This is mainly due to poor paleomagnetic data coverage for Permian times for Africa, core element of Pangea. Paleomagnetic data for Adria, thought to be the African prom...

The Zagros foreland basin is an important sedimentary archive for the tectonic and paleoclimatic evolution of the Zagros Mountains and the entire Neotethyan Arabia–Iran collision zone. By combining new geochemical high‐resolution whole rock XRF data with clay mineralogy and soluble salt geochemistry we propose an evolution of the sedimentary enviro...

Understanding the stabilization of cratons and how this is related to the onset of plate-tectonics is among the most important questions in geoscience. The assembly of Earth’s first supercontinent Columbia represents the first lines of evidence for a global subduction network, when the oldest, deep subduction-related rocks have been reported. We co...

Kimberlite magmatism provides insights into periodic tectonothermal processes linked to the evolution of supercontinents. Paleozoic and Mesozoic kimberlites overlapping with the Pangea cycle are exposed in the Amazonian Craton (Pimenta Bueno field) and the Neoproterozoic Brasília Belt. Phlogopite in mantle xenoliths in kimberlites from the Amazonia...

The Arabian-Eurasian collision zone results from a complex geodynamic evolution that is partially preserved in large-scale terranes stretching from the Mediterranean to Tibet. Integral to the evolution is the Permian breakup of Gondwana and the formation of a collection of microcontinents, termed Cimmeria, which accreted to the southern Eurasian ma...

We present statistical analysis of a compilation of observational constraints on the Precambrian length of day and find that the day length stalled at about 19 h for about 1 billion years during the mid-Proterozoic. We suggest that the accelerative torque of atmospheric thermal tides from solar energy balanced the decelerative torque of lunar ocean...

The paleogeographic position of Egypt through the Phanerozoic is tightly connected to the motion of the African continent. Paleogeographic studies using paleomagnetism of rock samples from Egypt range back to the 70s and 90s of the last century, but they also continued until very recent times. Paleomagnetic data generally confirm that Egypt was par...

The Zagros Mountain belt in Iran comprises an extensive record of Mesozoic and Cenozoic deposits uplifted by collision of the Arabian and Iranian continental plates. This area has been shown to provide important information to decipher the climatic history of Western Asia, especially regarding the evolution of deserts in Mesopotamia and Northern Ar...

The geodynamic evolution of the South Armenian Block (SAB) within the Tethyan realm during the Palaeozoic to present-day is poorly constrained. Much of the SAB is covered by Cenozoic sediments so that the relationships between the SAB and the neighbouring terranes of Central Iran, the Pontides and Taurides are unclear. Here we present new geochrono...

Earth’s thermo-tectonic evolution determines the way the planet’s interior and surface interact and shows temporal changes in both trends and periodic rhythms. By sampling the subcontinental lithospheric mantle that represents the interface between the convecting mantle and the crust, carbonatite and kimberlite should be ideal rock types for docume...

Plain Language Summary Earth's evolution is characterized by the recurring assembly of most tectonic plates into one single supercontinent. There is mounting evidence that at least three supercontinents existed throughout Earth history. This cycle of supercontinents potentially played an important role for the evolution of life and is inextricably...

Available online xxxx Editor: C.M. Petrone Keywords: plume subduction hotspot track large igneous province mantle dynamics Columbia supercontinent The concurrence of both global orogenesis and large igneous provinces (LIPs) from 2200-1600 Ma remains enigmatic. This apparent contradiction of top-down and bottom-up geodynamics occurred during assembl...

Interpretation of Earth's oldest preserved crustal archive, the Jack Hills zircon of Western Australia, has been controversial in terms of the onset of plate tectonics. We conduct time-series analysis on hafnium isotopes of the Jack Hills zircon and reveal an array of statistically significant cycles that are reminiscent of plate-tectonic subductio...

Diese Forschungsarbeit wurde initiiert, um die Stratigraphie und Petrogenese der pyroklastischen Gesteine der Aragaz-Vulkanprovinz (AVP, Armenien) zu untersuchen und ihre Eruptionszentren zu ergründen. Ein Hauptziel der als Promotionsprojekt der Erstautorin an der TU Bergakademie Freiberg angelegten Arbeit war die Beschreibung der chemischen und te...

We present an updated time frame for the 30 m thick late Miocene sedimentary Trachilos section from the island of Crete that contains the potentially oldest hominin footprints. The section is characterized by normal magnetic polarity. New and published foraminifera biostratigraphy results suggest an age of the section within the Mediterranean biozo...

We present paleo- and rock magnetic results from a well-dated, 21 m-thick, Late Pleistocene continental sedimentary section located in southern Germany. Rock magnetic measurements reveal a complex magnetic mineralogy dominated by low coercivity minerals likely related to single domain biogenic magnetite and biogenic or early diagenetic greigite. In...

The snowball Earth hypothesis—that a runaway ice-albedo feedback can cause global glaciation—seeks to explain low-latitude glacial deposits, as well as geological anomalies including the re-emergence of banded iron formation and “cap” carbonates. One of the most significant challenges to snowball Earth has been sedimentological cyclicity that has b...

The evolution of the present-day African savannah fauna has been substantially influenced by the dispersal of Eurasian ancestors into Africa. The ancestors evolved endemically, together with the autochthonous taxa, into extant Afrotropical clades during the last 5 million years. However, it is unclear why Eurasian ancestors moved into Africa. Here...

Many Archean cratons exhibit Paleoproterozoic rifted margins, implying they were pieces of some ancestral landmass(es). The idea that such an ancient continental assembly represents an Archean supercontinent has been proposed but remains to be justified. Starkly contrasting geological records between different clans of cratons have inspired an alte...

The current shape of Australia is largely an artifact of the previous supercontinent, Pangea. The Great Australian Bight to the south was shaped by Australia and Antarctica breaking apart roughly 90 million years ago, and New Zealand drifting away about 10 million years later, forming the eastern coast of the continent. Nevertheless, Australia has...

Paleogeographic reconstructions largely rely on paleomagnetic data, mostly in the form of paleomagnetic poles. Compilations of poles are used to determine so called apparent polar wander paths (APWPs), which capture the motion through time of a particular location with respect to an absolute reference frame such as the Earth’s spin axis. Paleomagne...

The Australia-Laurentia connection in the Paleoproterozoic to Mesoproterozoic supercontinent Nuna is thought to have initiated by ca. 1.6 Ga when both continents were locked in a proto-SWEAT (southwestern U.S.–East Antarctic) configuration. However, the longevity of that configuration is poorly constrained. Here, we present a new high-quality paleo...

The ca. 1.4 Ga Velkerri and Xiamaling Formations, in Australia and the north China craton, respectively, are both carbonaceous shale deposits that record a prominent euxinic interval and were intruded by ca. 1.3 Ga dolerite sills. These similarities raise the possibility that these two units correlate, which would suggest the occurrence of widespre...

The earliest evidence for subduction, which could have been localized, does not signify when plate tectonics became a global phenomenon. To test the antiquity of global subduction, we investigated Paleoproterozoic time, for which seismic evidence is available from multiple continents. We used a new high-density seismic array in North China to image...

Voluminous early to middle Pleistocene pyroclastic flow deposits were generated from Mount Aragats (Aragats Volcanic Province, AVP), one of the largest volcanoes in the Arabia-Eurasia continental collision zone. Here we report paleomagnetic results, in combination with anisotropy of magnetic susceptibility (AMS) analysis, from 31 outcrops belonging...

Multidimensional scaling (MDS) has become an important tool in detrital zircon geochronology for discriminating and comparing multiple samples, especially where large datasets are concerned. However, the non-parametrical test statistics used in MDS (e.g., Kolmogorov–Smirnov [K-S] or Kuiper) to calculate differences between detrital zircon samples a...

The most dominant features in the present-day lower mantle are the two antipodal African and Pacific large low-shear-velocity provinces (LLSVPs). How and when these two structures formed, and whether they are fixed and long lived through Earth history or dynamic and linked to the supercontinent cycles, remain first-order geodynamic questions. Hotsp...

Many ideas have been proposed to explain the origin of bipedalism in hominins and suspension in great apes (hominids); however, fossil evidence has been lacking. It has been suggested that bipedalism in hominins evolved from an ancestor that was a palmigrade quadruped (which would have moved similarly to living monkeys), or from a more suspensory q...

Precise age data are a basic prerequisite for the correlation of a sedimentary succession with the Global Time Scale, which in turn allows one to place its biotic and other data in a global context. In the North Alpine Foreland Basin (NAFB), a patchy distribution of outcrops and uncertainties in the correlation of strata have led to conflicting age...

The Pontocaspian (Black Sea - Caspian Sea) region has a very dynamic history of basin development and biotic evolution. The region is the remnant of a once vast Paratethys Sea. It contains some of the best Eurasian geological records of tectonic, climatic and paleoenvironmental change. The Pliocene-Quaternary co-evolution of the Black Sea-Caspian S...

[1] While cap dolostones are integral to the provocative Snowball Earth hypothesis, the current depositional model does not account for multiple geological observations. Here we propose a model that rationalises paleomagnetic, sequence‐stratigraphic and sedimentological data and supports rapid deglaciation with protracted cap dolostone precipitatio...

The two dominant features in the present-day mantle are the antipodal African and Pacific Large Low Shearwave Velocity Provinces (LLSVPs), or superplumes. How were these two structures formed? Are they fixed and long-lived through Earth history, or dynamic and linked to the supercontinent cycles? Such first-order questions concerning how geodynamic...

Hafnium isotopes of zircon represent a well-dated proxy for the evolution of magmatic systems through Earth history. Time series analysis on the hafnium isotopes of zircon reveals a hierarchy of statistically significant periodic signals spanning multiple orders of magnitude (10⁶–10⁹ year cycles). We attribute the hierarchy of cyclicity to organizi...

The supercontinent cycle of episodic assembly and breakup of almost all continents on Earth is commonly considered the longest period variation to affect mantle convection. However, global zircon Hf isotopic signatures and seawater Sr isotope ratios suggest the existence of a longer-term variation trend that is twice the duration of the supercontin...

We present new paleo- and rock magnetic results from the ca. 1792 Ma Hart Dolerite sills that intrude the strata of the Kimberley craton, Western Australia. From 24 sites sampled, 23 are directionally clustered and the site mean directions were used to calculate a grand mean direction. Ten of the 23 sites have 95% confidence intervals (α95) less th...

A pilot palaeomagnetic study was conducted on the recently dated with in situ SHRIMP U-Pb method at 1134 ± 9 Ma (U-Pb, zircon and baddeleyite) Bunger Hills dykes of the Mawson Craton (East Antarctica). Of the six dykes sampled, three revealed meaningful results providing the first well-dated Mesoproterozoic palaeopole at 40.5°S, 150.1°E (A95 = 20°)...

We present new paleomagnetic results for the early and middle Permian (18 sites and 167 samples) from sedimentary and volcanic rocks from northern and central-southern Sardinia (Italy). Characteristic directions magnetization have been retrieved using stepwise thermal demagnetization techniques. The bedding corrected site mean directions for the no...

The Rhenodanubian Flysch zone (RDF) is a Lower Cretaceous–lower Palaeocene turbidite succession extending for ∼500 km from the Danube at Vienna to the Rhine Valley (Eastern Alps). It consists of calcareous and siliciclastic turbidite systems deposited in a trench abyssal plain. The age of deposition has been estimated through micropalaeontologic da...

A palaeomagnetic study was carried out on the newly identified 1888 ± 9 Ma Boonadgin dyke swarm of the Yilgarn Craton in Western Australia. The Bonnadgin dykes yield a mean direction of magnetisation of D = 143°, I = 13°, k = 37 and α95 = 8°, based on samples from 10 diabase dykes, with a corresponding palaeopole at 47° S, 235° E, A95 = 6°. A posit...

While it is well established that the Earth’s magnetic field is generated by a self sustaining dynamo that reversed its polarity at irregular intervals in the geological past, the very mechanisms causing field reversals remain obscure. Paleomagnetic reconstructions of polarity transitions have been essential for physically constraining the underlyi...

In the northern Alpine region only a few lacustrine sediment sequences are known from the period of the last glacial, regionally assigned as Würmian. Even less is known about Alpine palaeoenvironments prior to the last glacial maximum (LGM). The recently discovered sediment sections at the Nesseltalgraben site (northern Alps, southern Germany) pres...

The Derim Derim Suite of magmatic sills (1324 ± 4 Myr1) intrude Mesoproterozoic sediments of the Roper Group, McArthur Basin. While intersected by numerous mineral and petroleum wells, no volcanic equivalents have been identified, but these sills have been correlated1,2 with the Galiwinku Dykes (1325 ± 36 Myr3). Intruding at multiple stratigraphic...

Glaciogenic sediments of Palaeozoic age and Metasedimets of the Tambien Group of the Arabian Nubian Shield both in Northern Ethiopia have been sampled for palemagnetic investigations. The results from both are respectively presented. The Glacial sediments; although there was no doubt about the glacial origin of these rocks, there has been a debate...

Dating fossil hominids and reconstructing their environments is critically important for understanding human evolution. Here we date the potentially oldest hominin, Graecopithecus freybergi from Europe and constrain the environmental conditions under which it thrived. For the Graecopithecus-bearing Pikermi Formation of Attica/Greece, a saline aeoli...

Geopedal structures in giraffid long-bones from Pyrgos Vassilissis. Sediment infill of bones (a, TE 124; b, TE 130) overgrown by geopetal sparry calcite, which provides a palaeo-horizon for palaeomagnetic analysis of Pyrgos. (TIF)

Grain-size spectra for palaeosol samples from the Graecopithecus horizon of Pyrgos (Pikermi Formation, Attica Basin). Measured grain size distribution (GSD, shown as a grey area in each diagram) versus fitted grain spectra (red line) using the simplified end-member (EM) spectra (Fig 11) from the Pikermi Formation of the nearby Mesogea basin (EM1—bl...

Ionic composition of soluble salts from eolian silt of the Pikermi Formation (Attica and Mesgea Basins). (XLSX)

Measurements of Hippotherium brachypus from Pyrgos Vassilissis. Dimensions (in mm) of the cranial fragment AMPG 02, the premolar row TE 114, and the mandibular fragment AMPG 03. The definitions of measurements (italics) follows [84]. (XLSX)

Giraffid mandibular tooth dimensions. cf. Palaeotragus sp. from Pyrgos Vassilissis, compared to Palaeotragus rouenii and Bohlinia attica (MNHN: Muséum National d’Histoire Naturelle, Paris) (in mm; L–length, W–width, H—height). Heights of unworn teeth are in bold. (XLSX)

Grain-size spectra for samples from Azmaka palaeosoils (Ahmatovo Formation, Upper Thrace Basin). Measured GSD versus fitted grain spectra using simplified end-member (EM) spectra from the Pikermi Formation (Mesogea Basin) for the aeolian components only (EM1—blue, EM2—magenta). The r2 value for each diagram represents the variance of the GSD explai...

Detailed counts of pollen and micro-charcoal from the Pikermi Formation (Athens and Mesogea Basins). (XLSX)

Pedogenic carbonate δ18O and δ13C data from the Pikermi Formation (Athens and Mesogea Basins). (XLSX)

LA-SF-ICP-MS U-Pb-Th data of detrital zircons. Sample CA 2.75, n = 60 measured zircon grains, red siltstone, Pikermi Formation, Red Conglomeratic Member, sub-section Chomateri A (coordinates: N 38° 00’ 48”, E 23° 57’ 46”). Grey shading indicate recommended ages in the range of concordance of 90–110%. Discordant ages (below or above the range of con...

Detailed counts of phytolith types (in %) and phytolith indices from the Pikermi Fm (including Pyrgos), Attica and Mesgea Basins. (XLSX)

Measurements of Hippotherium brachypus from Pyrgos Vassilissis. Dimensions (in mm) of the upper and lower check teeth. The measurements L (length) and W (width) are taken on the occlusal surface and follows [84]. (XLSX)

Grain-size spectra for samples from Rafina (top of Rafina Formation, Mesogea Basin) and Cucuron (Mt Luberon, Vaucluse, France). Measured GSD versus fitted grain spectra using the simplified EM spectra from the Pikermi Formation (Mesogea Basin) for aeolian components only (EM1—blue, EM2—magenta). The r2 value for each diagram represents the variance...

Ages and age distribution of aeolian zircons from the Pikermi Formation (Mesogea Basin). a, b, Concordia plots of U-Pb LA-ICP-MS data for sample CA 2.75 for all measurements (a) and of the younger zircon grains in an age range of 0 to 1500 Ma (b). c, d, Combined binned frequency and probability density distribution plots of U-Pb LA-ICP-MS ages of d...

Phytolith taxonomy and interpretation. (DOCX)

Sedimentology. (DOCX)

Measurements of Tragoportax macedoniensis from Pyrgos Vassilissis and Dytiko (DTK, DIT, DKO). Dimensions (in mm, L–length) of the upper tooth series. Values in parentheses indicate approximate measurements. Data from Dytiko according to [85]. (XLSX)

U-Th-Pb isotopes. (DOCX)

Measurements of Tragoportax macedoniensis from Pyrgos Vassilissis and Dytiko (DTK, DIT, DKO). Horn-core basal dimensions (in mm). APD–anteroposterior diameter of the horn-core at its base; TD–transverse diameter of the horn-core at its base. Values in parentheses indicate slightly approximate measurements. Data from Dytiko according to [85]. (XLSX)

Sedimentological and statistical properties of end-member loadings obtained with EMMAgeo. (DOCX)

End member modelling of grain-size spectra. (DOCX)