Determining sedimentation ages of high-grade metamorphic gneisses by their palynological record: a case study in the northern Schwarzwald (Variscan Belt, Germany)

Hanel, Michael; Montenari, Michael; Kalt, Angelika

doi:10.1007/s005310050245

Cited by 29 publications

(26 citation statements)

References 42 publications

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“…Although this "fossil" record decreases in outcrop abundance the older the rocks are (basically due to burial, erosion, subduction, and metamorphism), biosignatures can be found in sedimentary rocks (Schopf 1983;Schopf and Klein 1992;Schieber et al 2007;Noffke 2010), but also in igneous (Banerjee et al 2006;Furnes et al 2004Furnes et al , 2007bFliegel et al 2010) and metamorphic (Franz et al 1991;Hanel et al 1999: Squire et al 2006Bernard et al 2007;Schiffbauer et al 2007Schiffbauer et al , 2012Schiffbauer and Xiao 2009;Zang 2007) rocks of all ages.…”

Section: A Note On Biosignaturesmentioning

confidence: 99%

Early life on land and the first terrestrial ecosystems

Beraldi-Campesi¹

2013

Ecol Process

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Terrestrial ecosystems have been largely regarded as plant-dominated land surfaces, with the earliest records appearing in the early Phanerozoic (<550 Ma). Yet the presence of biological components in pre-Phanerozoic rocks, in habitats as different as soils, peats, ponds, lakes, streams, and dune fields, implies a much earlier type of terrestrial ecosystems. Microbes were abundant by~3,500 Ma ago and surely adapted to live in subaerial conditions in coastal and inland environments, as they do today. This implies enormous capacities for rapid adaptations to changing conditions, which is supported by a suggestive fossil record. Yet, evidence of "terrestrial" microbes is rare and indirect in comparison with fossils from shallow or deeper marine environments, and its record has been largely overlooked. Consequently, the notion that microbial communities may have formed the earliest land ecosystems has not been widely accepted nor integrated into our general knowledge. Currently, an ample record of shallow marine and lacustrine biota in~3,500 Ma-old deposits, together with evidence of microbial colonization of coastal environments~3,450 Ma ago and indirect geochemical evidence that suggests biological activity in >3,400 Ma-old paleosols endorses the idea that life on land perhaps occurred in parallel with aquatic life back in the Paleoarchean. The rapid adaptations seen in modern terrestrial microbes, their outstanding tolerance to extreme and fluctuating conditions, their early and rapid diversification, and their old fossil record collectively suggest that they constituted the earliest terrestrial ecosystems, at least since the Neoarchean, further succeeding on land and forming a biomass-rich cover with mature soils where plant-dominated ecosystems later evolved. Understanding how life diversified and adapted to non-aquatic conditions from the actualistic and paleontological perspective is critical to understanding the impact of life on the Earth's systems over thousands of millions of years.

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Section: A Note On Biosignaturesmentioning

confidence: 99%

Early life on land and the first terrestrial ecosystems

Beraldi-Campesi¹

2013

Ecol Process

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“…All three units were subjected to a final high-temperature low-pressure metamorphic event at about 330 Ma (Kalt et al 1994;Lippolt et al 1994), with P-T conditions of 730-780°C and 0.42-0.45 GPa . The pre-metamorphic history and the depositional conditions of the metasediments in the Schwarzwald are very roughly constrained by palynological data (Montenari 1996;Hann and Sawatzki 1998;Hanel et al 1999;Montenari et al 2000), which are consistent with sediment deposition in Neoproterozoic to Early Palaeozoic marine environments. The genetic relations between the metasediments hosted in the tectonometamorphic units, the timing of sediment deposition, and the palaeogeographic positions of the corresponding marine basins are yet unknown.…”

Section: Geological Setting and Samplesmentioning

confidence: 80%

“…This could favour an onset of sedimentation in the basins represented by samples St-4-1 and OM-3-2 later than the Middle Cambrian. Hanel et al (1999) found palynological evidence (chitinozoa) for marine sedimentation of Ordovician age in amphibolite-facies paragneisses from a borehole in the Northern Schwarzwald close to the OGC. A HT event at about 480 Ma, suggested for Unit 1 by various authors on the basis of zircon dating (Steiger et al1973;Kober et al 1986), Rb-Sr whole rock data (Hofmann and Ko¨hler 1973) and garnet Pb-Pb dating (Chen et al 1998, cited in Chen et al 2000, may be taken as a further argument for Ordovician consolidation of the metasediments of Unit 1 and the OGC.…”

Section: Constraints On Sedimentation Episodes and Palaeogeographic Pmentioning

confidence: 94%

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SHRIMP dating of zircons from high-grade metasediments of the Schwarzwald/SW-Germany and implications for the evolution of the Moldanubian basement

Kober

Kalt

Hanel

et al. 2004

Contributions to Mineralogy and Petrology

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Four metasedimentary zircon populations from different tectonometamorphic units of the Central and the Northern Schwarzwald (Variscan belt, SWGermany) were investigated using SEM, cathodoluminescence and SHRIMP dating. Despite partially strong modifications of primary internal morphologies during Variscan metamorphism at amphibolite (750°C, 0.4-0.6 GPa) and granulite-facies conditions (950-1,000°C, 1.4-1.8 GPa), many grains show well-preserved protolith ages. The detritus indicates a northern Gondwana origin and different Palaeozoic episodes of sediment deposition and consolidation. Two of the studied sediments were deposited in Cambrian/early-Ordovician times and consolidated in positions close to northern Gondwana. Late Ordovician and rare Devonian detritus from sediments of two other tectonometamorphic units indicates much later sedimentation close to the leading edge of Gondwana or a terrane assemblage during northern drift towards Laurussia. Subsolidus growth of new zircon due to Variscan granulite facies metamorphism of one of the tectonometamorphic units is precisely dated at 335±2 Ma.

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“…Aunque este registro 'fósil' se reduce entre más antiguas son las rocas, diferentes tipos de biofirmas se han podido encontrar en rocas sedimentarias (Schopf, 1983;Schopf y Klein, 1992;Schieber et al, 2007;Noffke, 2010), ígneas (Banerjee et al, 2006;Furnes et al, 2004Furnes et al, , 2007bFliegel et al, 2010) y metamórficas (Franz et al, 1991;Hanel et al, 1999;Squire et al, 2006;Bernard et al, 2007;Schiffbauer et al, 2007Schiffbauer et al, , 2012Schiffbauer y Xiao, 2009;Zang, 2007), de todas las edades.…”

Section: Nota Sobre Biofirmasunclassified

La vida temprana en la Tierra y los primeros ecosistemas terrestres

Beraldi-Campesi¹

2014

BSGM

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La vida temprana en la Tierra y los primeros ecosistemas terrestres 65 ResumenLos ecosistemas terrestres han sido considerados tradicionalmente como superficies dominadas por plantas, cuyos primeros registros datan del Fanerozoico temprano (< 550 Ma/millones de años). Sin embargo, la presencia de componentes biológicos mucho más antiguos que las plantas en hábitats tan distintos como suelos, turberas, estanques, lagos, arroyos y dunas, sugiere que los ecosistemas terrestres comenzaron a existir en la Tierra hace al menos 2700 Ma. Los microbios fueron abundantes hace ~3500 Ma y sin duda se adaptaron a vivir en condiciones subaéreas, en entornos intermareales y en zonas áridas y semiáridas, como lo hacen actualmente los microbios terrestres, y que tienen una enorme y rápida capacidad de adaptación a condiciones cambiantes. Todo ello está respaldado por el registro fósil. No obstante, esta evidencia es inusual e indirecta en comparación con fósiles de ambientes marinos, superficiales o profundos, y su registro ha sido poco atendido. En consecuencia, la noción de que fueron comunidades microbianas las que formaron los primeros ecosistemas terrestres no ha sido ampliamente difundido ni incorporado conceptualmente en la sociedad. Hoy conocemos un amplio registro fósil de biota marina somera y lacustre a partir de los ~3500 Ma, así como microbios colonizando ambientes costeros desde hace ~3450 Ma y evidencia indirecta de actividad biológica en paleosuelos de > 3400 Ma de edad. El tipo de ambientes, de donde proviene esta evidencia, sugiere que la vida terrestre se produjo casi en paralelo con la vida acuática en el Arqueano. Las rápidas adaptaciones observadas en microbios actuales, su excepcional tolerancia a condiciones extremas y fluctuantes, su rápida y temprana diversificación y su antiguo registro fósil, indican que los primeros ecosistemas terrestres fueron exclusivamente microbianos. Es factible que los microbios contribuyeran en la formación de los primeros suelos donde las plantas se desarrollaron más tarde. Comprender cómo la vida se diversificó y adaptó a las condiciones terrestres es fundamental para entender su impacto en los sistemas terrestres durante millones de años. Beraldi-Campesi 66 661. Introducción Definición de terrestreLos ambientes terrestres seguramente han existido a través de toda la historia geológica de la Tierra a menos que su superficie estuviera permanentemente bajo el agua, lo cual no es aceptablemente realista. La definición de 'terrestre' no es tan trivial como parece. Aunque aquí se define como un ambiente 'no acuático', la distinción entre lo marino y lo terrestre atraviesa un amplio espectro de ambientes transicionales, donde lo acuático y lo no-acuático evolucionan y superponen en el tiempo. Comúnmente se entiende que un entorno terrestre (sobre el nivel del mar), puede incluir ambientes acuáticos (lagos cubiertos o no de hielo, lagunas y humedales, turberas, ríos y arroyos, campos geotérmicos) y no-acuáticos (especialmente zonas con poca lluvia). Estos hábitats pueden experimen...

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Determining sedimentation ages of high-grade metamorphic gneisses by their palynological record: a case study in the northern Schwarzwald (Variscan Belt, Germany)

Cited by 29 publications

References 42 publications

Early life on land and the first terrestrial ecosystems

Early life on land and the first terrestrial ecosystems

SHRIMP dating of zircons from high-grade metasediments of the Schwarzwald/SW-Germany and implications for the evolution of the Moldanubian basement

La vida temprana en la Tierra y los primeros ecosistemas terrestres

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