Axel Gerdes

Goethe-Universität Frankfurt am Main · Institut für Geowissenschaften

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Abstract In the late Permian and Triassic, the continental Mitu Gro...

Mass transfer across the crust‐mantle boundary is a fundamental process governing planetary differentiation, the evolution of geochemical reservoirs and ore formation, controlled by physicochemical conditions at the crust‐mantle interface. In situ trace‐element, clinopyroxene ⁸⁷Sr/⁸⁶Sr and garnet Fe³⁺/ΣFe of kimberlite‐borne eclogite xenoliths from...

A sample from the Punta de li Tulchi granulitized eclogite, cropping out within the Variscan migmatites of NE Sardinia, was investigated by LA-ICPMS garnet U–Pb age dating. The majority of U-Pb analyses define a regression line with a lower intercept date of 395.1 ± 9.8 / 12.4 Ma. In addition, nine data points define a second regression line with a...

Reconstructing the original geometry of a high-pressure tectonic unit is challenging but important to understand the mechanisms of mountain building. While a single nappe is subducted and exhumed, nappe-internal thrusts may disrupt it into several subunits. The Middle-CBU nappe of the Cycladic Blueschist Unit (Hellenide subduction orogen, Greece) s...

Integrated petrological, geochemical, isotopic and thermobarometric study of metasedimentary rocks from the amphibolite‐ to granulite‐facies transition zone of the Eastern Dharwar Craton (EDC), South India, has provided new insight into the evolution of the lower continental crust in this region. Phase equilibrium modelling of metapelites and metag...

The chronology of the Cenozoic “Namib Group” of the Namib Desert is rather poorly understood and lacks direct radiometric dating. Thus, the paleoclimate and landscape evolution of the central Namib Desert remains imprecise, complicating the detailed search for global and/or local forcing factors for the aridification of the Namib. The widespread oc...

The 0–2.5 Ma volcanism in Easter Island (Rapa Nui) emerges just east of the East Pacific Rise on young (Pliocene, 3–4.8 Ma) ocean floor. Here, we report the finding of mantle-derived zircon grains retrieved from Easter Island beach sands and red soils that are much older than the Easter Island volcanism and its underlying lithosphere. A large popul...

The Levant Basin in the Eastern Mediterranean contains an ∼3-km-thick, predominantly siliciclastic section of Oligocene−Miocene age, which hosts large hydrocarbon reservoirs (“Tamar Sands Play”). Here, we present a provenance study of Oligocene−Miocene sandstones based on detrital zircon U-Pb-Hf and heavy mineral assemblages. Samples were retrieved...

This contribution presents new insights into the origin and age relationships of the Geyer tin deposit in the Erzgebirge, Germany. Tin mineralization occurs in skarns, greisen, and in cassiterite-bearing fluorite-quartz veins. Skarn alteration replaces marble layers of the Cambrian Jáchymov Group and occurs in two clearly distinct stages. The first...

Rocks exposed along both sides of the Smith Sound in Ellesmere Island and NW Greenland record the tectono‐sedimentary evolution of the whole Phanerozoic, including two periods of mountain building—the Palaeozoic Ellesmerian Orogeny and the Palaeogene Eurekan Orogeny—and the formation of two major sedimentary basins, the Franklinian and the Sverdrup...

A major step in the evolution of continental crust on Earth was the time in which continental crust transitioned from being mostly submarine to mostly subaerial. This change is intimately linked with the volumetric accumulation of continental crust on Earth and the onset of plate tectonics, the timing of both is still debated among scholars. Differ...

Carbonate formation during the alteration of oceanic crust is a global CO2 sink. Its timing and controls are not well understood, particularly in volcanic seamounts, which react with seawater over tens of millions of years. We report in situ U-Pb age dates of carbonate vein and void fill in 50−74 Ma basaltic basement of the Louisville Seamount Chai...

The chronology of the Cenozoic, so called ‘Namib Group’ of the Namib Desert is rather poor in terms of direct radiometric dating. Most of the chronological information is based on the ostrich shell biochronostratigraphy. The widespread occurrence of calcretes and silcretes in the Namib Desert makes it possible to date important phases of landscape...

The lithospheric mantle as sampled by peridotite xenoliths in some continental settings resembles the source of mid-ocean ridge basalts (MORB). Whether this resemblance is a primary feature or the result of post-formation secondary processes remains controversial. Here, the age, origin and thermochemical evolution of fertile continental mantle are...

The recent discovery of Ediacaran ophiolites in the SW Iberian Massif has made it possible to pinpoint the evolution of the Cadomian basement of Europe. The Calzadilla and Merida ophiolites (gabbroic protoliths dated at c. 600 and 594 Ma, respectively) have geochemical characteristics typical of supra-subduction zone ophiolites. They are interprete...

Demantoid is a rare Cr-bearing variety of andradite garnet historically mined in the Middle Urals of Russia, where its mode and time of formation remain controversial. A first direct in situ U-Pb LA-ICP-MS dating of demantoid was carried out on samples with extremely low U content obtained from the Karkodinskoe and Poldnevskoe deposits, both of whi...

The Levant Basin in the Eastern Mediterranean contains a ~3 km-thick, predominantly siliciclastic section of Oligocene-Miocene age, which hosts large hydrocarbon reservoirs (“Tamar Sands Play”). A fundamental question raised with respect to this siliciclastic section concerns its origin and the sedimentary pathways into the deep basin. Here we pres...

Knowledge of pressure-temperature-time (P-T-t) evolution of Archean high-grade (deep crustal) metamorphic rocks is important for deciphering the nature of Archean tectonic processes. However, exposures of such rocks are limited in the present rock record. Here, we study a suite of high-grade, mafic rocks that are present along a crustal-scale shear...

The Levant Basin in the Eastern Mediterranean contains a ~3 km-thick, predominantly siliciclastic section of Oligocene-Miocene age, which hosts large hydrocarbon reservoirs (“Tamar Sands Play”). A fundamental question raised with respect to this siliciclastic section concerns its origin and the sedimentary pathways into the deep basin. Here we pres...

The dinosaur-bird transition involved several anatomical, biomechanical, and physiological modifications of the theropod bauplan. Non-avian maniraptoran theropods, such as Troodon, are key to better understand changes in thermophysiology and reproduction occurring during this transition. Here, we applied dual clumped isotope (Δ47 and Δ48) thermomet...

The process of recrystallization affecting dolomitic successions remains a longstanding enigma in carbonate research. Recrystallization influences the accuracy of genetic dolomitization models as well as the prediction of porosity and permeability distribution within dolomitic reservoirs. We investigate early-formed dolomites of the Upper Jurassic...

The Atacama Desert is one of the driest and oldest deserts on Earth, with extremely low precipitation rates (<2 mm/yr). Mostly abiotic hyperarid environmental conditions prevail, and surface processes act at extremely low rates over the long‐term. To gain knowledge about the rate of surface processes and age of landscapes in desert environments, te...

The Levant Basin is surrounded by continental areas that were uplifted during the Oligocene-Miocene. On its southern and eastern sides, it is flanked by the wide Red Sea domal structure, whereas in the northeast it is bordered by the Tauride-Zagros orogenic belt. Coeval with the rise of its surroundings, a ~3 km-thick siliciclastic section was depo...

Concerning their provenance and age, the nappes of the Uppermost Unit of Crete are counted among the most enigmatic constituents of the Eastern Mediterranean. U–Pb dating of zircons separated from metavolcanic rocks of the Preveli nappe exposed near Lefkogia yielded Triassic emplacement ages at 237.3 ± 1.8, 241.5 ± 1.2 and 242.1 ± 1.2 Ma. U–Pb gran...

Results of a combined petrological, geochemical and geochronological study suggest that metasedimentary rock units in the Krndija region of the Slavonian Mountains, Croatia, were affected by at least three major tectonometamorphic imprints: during the Middle Ordovician (Sardic event), the early Carboniferous (Variscan event), and the Cretaceous (Al...

Petrographic observations and in situ U–Pb ages of melilitites, foidites, basanites, phonolites, and trachytes from the southern part of the Central European Volcanic Province (CEVP) and related plutonic inclusions therein reveal two distinct age groups separated by a gap of ~ 20 Myr. A late Cretaceous to early Eocene group (~ 73–47 Ma; Taunus, Low...

In this contribution we report the first systematic study of zircon U-Pb geochronology and δ18O-εHf(t) isotope geochemistry from ten islands of the hot-spot related Galapagos Archipelago. The data extracted from the zircons allow them to be grouped into three types: 1) young zircons (0 – ~4 Ma) with εHf(t) (~5 – 13) and δ18O (~4 – 7) isotopic mantl...

The Morelos district, located in the center of the Guerrero gold belt, Guerrero State, southern Mexico, has been the site of several recent gold ± copper skarn discoveries (total of ~8.5 Moz Au) associated with Upper Cretaceous-Paleocene granodiorite intrusions. The Limon, Guajes, and Media Luna skarn deposits developed along the contact of the El...

Enriched shergottites contain interstitial Si‐rich mesostasis; however, it is unclear whether such mesostasis is formed by impact or magmatic processes. We use laser ablation multicollector inductively coupled plasma mass spectrometry U–Pb measurements of minerals within the interstitial Si‐rich mesostasis and of merrillite within the coarse‐graine...

In the SW Iberian Massif, the Ossa-Morena Complex contains a stack of units of different origin and tectonothermal evolution. Individual terranes of the complex record a Cadomian history, traditionally interpreted in relation to the dynamics of a peri-Gondwanan volcanic arc. The interpretation of the Cadomian terranes is a key issue in the reconstr...

The onset of plate tectonics on Earth brought about rapid accumulation of continental crust, and the transition of continental crust from being mostly submarine to mostly subaerial. Tracking the timing and rate of continental emergence has broad implications on the onset of plate tectonics and to our understanding of its operation in its early days...

Recent developments in analytical capabilities in the field of in situ laser ablation mass spectrometry (LA-ICPMS) have expanded the applications of U–Pb geochronometers in low-U minerals such as carbonates or garnets. The rapid evolution of the technique relies on well-characterized matrix-matched reference materials. In this article, we explore t...

U-Pb dating and geochemical analyses (δ18O, δ13C, Δ47, 87Sr/86Sr and elemental composition) have been applied to fracture-filling calcite veins and host carbonates from the Bóixols-Sant Corneli anticline, which developed along the front of the Bóixols thrust sheet in the Southern Pyrenees. This robust dataset is used to determine: (i) the absolute...

The detrital zircon grains from two catchments in the East Eifel Volcanic Field consist of crystals sourced from proximal deposits of Quaternary trachytic–phonolitic volcanic centres, Hocheifel Paleogene trachytic rocks and the Paleozoic basement. The outcrop patterns indicate the derivation of a significant detrital zircon population from deposits...

Here, we present in situ U–Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) ages of andradite-grossular garnet from four magmatic-hydrothermal polymetallic skarn prospects in the Schwarzenberg District, Erzgebirge (Germany), located in the internal zone of the Variscan Orogenic Belt. Within the geochronological framework o...

In order to present a conclusive new correlation model for Neoproterozoic glacial units of southern Namibia, ten different sections and a variety of samples thereof were studied and analysed with respect to field relationships, whole rock geochemistry, zircon U-Pb dating as well as Th-U ratios, Hf isotopic measurements and zircon grain size analyse...

The Altenberg–Teplice Volcanic Complex (ATVC) is a large ~ NNW–SSE trending volcano-plutonic system in the southern part of the Eastern Erzgebirge (northern Bohemian Massif, south-eastern Germany and northern Czech Republic). This study presents high precision U–Pb CA-ID-TIMS zircon ages for the pre-caldera volcano-sedimentary Schönfeld–Altenberg C...

This study integrates field structural data, petrographic and geochemical (δ¹⁸O, δ¹³C, Δ47, ⁸⁷Sr/⁸⁶Sr, and elemental composition) analyses and U–Pb dating of calcite veins cutting the Bóixols-Sant Corneli anticline (Southern Pyrenees) in order to date and to investigate the spatio-temporal relationships between fluid flow and fold evolution. This E...

Situated between Africa and Eurasia in the eastern Mediterranean, the island of Cyprus has developed on the northern margin of the southern Neotethys by the accretion of three terrains, the Mamonia complex, the Troodos ophiolite, and the Kyrenia terrane. The Kyrenia terrane comprises a tectonic stack of Triassic to Eocene rock units interleaved wit...

The northern extent of the supercontinent Gondwana in the late Neoproterozoic-Cambrian is not well defined. In most localities the continental margin is covered by thick sedimentary successions, formed following the successive rifting of Tethyan Oceans that episodically detached continental terranes from the edge of the supercontinent. East of the...

Situated between Africa and Eurasia in the Eastern Mediterranean, the island of Cyprus has developed on the northern margin of the southern Neotethys by the accretion of three different terrains, the Mamonia Complex in the south, the Troodos ophiolite, and the Kyrenia terrane in the north. The Kyrenia terrane comprises imbricated tectonic slices of...

The Yacoraite Fm. (Salta rift, Argentina) consists of Maastrichtian-Danian lacustrine carbonate and siliciclastic deposits with interbedded volcanic ash layers, organized in four third-order stratigraphic sequences. It offers the exceptional opportunity to jointly apply in situ zircon and carbonate U-Pb (LA-ICPMS) geochronology that resulted in two...

Geothermobarometry shows that metapelite samples from Namche Barwa Complex (NBC) reached upper‐amphibolite to near‐granulite facies during the peak metamorphic stage, with similar conditions of ~700–750 °C/8–10 kbar, and then experienced retrograde metamorphism at ~630–700 °C/4–7 kbar. In‐situ monazite LA‐ICP‐MS U‐Th‐Pb dating suggests divergent me...

Situated between Africa and Eurasia in the eastern Mediterranean, the island of Cyprus has developed on the northern margin of the southern Neotethys by the accretion of three terrains, the Mamonia complex, the Troodos ophiolite, and the Kyrenia terrane. The Kyrenia terrane comprises a tectonic stack of Triassic to Eocene rock units interleaved wit...

Recent developments on analytical capabilities in the field of in situ laser ablation mass spectrometry (LA-ICPMS) have expanded the applications of U-Pb geochronometers in low-U minerals such as carbonates or garnets. Although the rapid evolution of the technique relies on well characterized matrix-matched reference materials, the use of non-matri...

The Yacoraite Formation (Salta rift, Argentina) consists of Maastrichtian–Danian lacustrine carbonate and siliciclastic deposits with interbedded volcanic ash layers, organized in four third‐order stratigraphic sequences. It offers the exceptional opportunity to jointly apply in situ zircon and carbonate U‐Pb laser ablation‐inductively coupled plas...

The tectonic significance of blueschist-facies rocks associated with the Indo-Myanmar ophiolite belt is uncertain, given the lack of detailed petrological study and the paucity of reliable age data for different stages in their geological evolution. Here, we present new integrated petrological and geochronological data for samples from the Nagaland...

The Menderes Massif in Turkey represents one of the largest metamorphic core complexes in the world. It is regarded as a section of lower continental crust exhumed along low-angle detachment faults in the Late Miocene during a period of extension that affected the entire Aegean province. Syn-extensional magmatic activity within the Menderes metamor...

The area northeast of Sudbury, Ontario, is well known for hosting one of the largest unexplained geophysical anomalies in the Canadian Shield, the Temagami Anomaly. In search of a geological explanation for this anomaly, low-grade metamorphic ultrabasic dykes have been discovered in the overlying Huronian Supergroup sedimentary rocks, both in outcr...

We studied detrital zircon from black sand of the Rhone River delta (southern France) which drains significant parts of Western Europe. Zircon U-Pb geochronology shows that the black sand is an extraordinary sampler of all major episodes of European magmatism peaking at 0.55 Ga (Cadomian), 0.45 Ga (Cenerian) and 0.31 Ga (Variscan). Hf in detrital z...

Analysis of cosmogenic nuclides produced in surface rocks and sediments is a valuable tool for assessing the rates of processes and the timing of events that shaped the Earth surface. The various nuclides that are used have specific advantages and limitations that depend on the time range over which they are useful, the type of material they are pr...

Svalbard’s Northwestern Basement Province is traditionally divided into the Albert I Land and the Biscayarhalvøya terranes. New U-Pb age data on zircon and monazite, structural and geochemical data provide first evidence of early Palaeozoic deposits south of the Biscayarhalvøya Terrane indicating the possible existence of a third terrane: the Germa...

We present structural, microfabric and strain data of a spessartite sill and its quartzmonzodiorite host that were affected by bulk constriction at T = ca. 660 °C. Constrictional deformation led to (1) subvertical prolate grain-shape fabrics, (2) increase of the sill's dip, (3) doubling of the sill's thickness, (4) mullions with cusps pointing into...

The accessories perovskite, pyrochlore, zirconolite, calzirtite and melanite from carbonatites and carbonate-rich foidites from the Kaiserstuhl are variously suited for the in situ determination of their U–Pb ages and Sr, Nd- and Hf-isotope ratios by LA-ICP-MS. The 143Nd/144Nd ratios may be determined precisely in all five phases, the 176Hf/177Hf r...

The northern Namibian Karoo-aged successions are part of a Gondwana-wide sedimentary system emerging at the Carboniferous-Permian boundary and existing for more than 50 Ma. The Karoo Supergroup sedimentary successions are of importance in understanding the evolution of the Karoo rift system. This study presents new whole-rock geochemical data combi...

Extensive morphological and age studies on more than 4600 detrital zircon grains recovered from modern sands of Namibia reveal complex mechanisms of sediment transport. These data are further supplemented by a zircon age database containing more than 100,000 single grain analyses from the entire southern Africa and allow for hypothesising of a larg...

The Upper Cretaceous carbonates along the Zagros thrust-fold belt “Harir-Safin anticlines” experienced extensive hot brine fluids that produced several phases of hydrothermal cements, including saddle dolomites. Detailed fluid inclusion microthermometry data show that saddle dolomites precipitated from hydrothermal (83–160 °C) and saline fluids (up...

The accessories perovskite, pyrochlore, zirconolite, calzirtite and melanite from carbonatites and carbonate-rich foidites from the Kaiserstuhl are variously suited for the in situ determination of their U-Pb ages and Sr, Nd-and Hf-isotope ratios by LA-ICP-MS. The 143 Nd/ 144 Nd ratios may be determined precisely in all five phases, the 176 Hf/ 177...

Abstract: Utilizing sophisticated tools in carbonate rocks is crucial to interpretating the origin and evolution of diagenetic fluids from the Upper Jurassic carbonate rocks along the Zagros thrust-fold Belt. The origin and evolution of the paleofluids utilizing in-situ strontium isotope ratios by high resolution laser ablation ICP-MS, integrated...

Late Paleozoic (Variscan) magmatism is widespread in Central Europe. The Lusatian Block is located in the NE Bohemian Massif and it is part of the Saxothuringian Zone of the Variscan orogen. It is bordered by two major NW-trending shear zones, the Intra-Sudetic Fault Zone towards NE and the Elbe Fault Zone towards SW. The scarce Variscan igneous ro...

The Kyrenia terrane of northern Cyprus comprises a tectonic stack of Triassic to Eocene rock units interleaved with basic and acid volcanics and minor metamorphic inliers, alongside an Oligocene‐Miocene flysch. Our U‐Pb‐Hf detrital zircon investigation in the Kyrenia Triassic to Eocene section reveals Precambrian, Silurian (∼430 Ma), Carboniferous...

The timing of vertical motions adjacent to the Dead Sea Transform plate boundary is not yet firmly established. We utilize laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb geochronology of carbonate cave deposits (speleothems) to constrain paleo-groundwater levels along the western margin of the Dead Sea Transform and pr...

Foidites and melilitites are strongly SiO2-undersaturated rocks that form by extremely low degrees of partial melting of the metasomatically overprinted lithospheric mantle. In Central Europe, they occur in volcanic fields, dike swarms or as isolated stocks and diatremes. Our detailed study on foidites from SW Germany indicates two distinct age gro...

The Mt. Gorzano Fault (MGF) is a major seismically active extensional fault of the central Apennines, responsible for the destructive Mw 6.0 Amatrice earthquake in 2016. The MGF developed during post-orogenic extensional tectonics, generating a continental basin in the hanging wall. The age of the onset of the MGF and the relationship among faultin...