TY - JOUR

T1 - Reconstructing Valanginian (Early Cretaceous) mid-latitude vegetation and climate dynamics based on spore-pollen assemblages

AU - Kujau, Ariane

AU - Heimhofer, Ulrich

AU - Hochuli, Peter A.

AU - Pauly, Sebastian

AU - Morales, Chloé

AU - Adatte, Thierry

AU - Föllmi, Karl

AU - Ploch, Izabella

AU - Mutterlose, Jörg

N1 - Funding Information: Special thanks are due to Benjamin Gréselle (Neftex Petroleum Consultants Ltd., Oxfordshire, UK) for his assistance during field work in France. Financial support from the DFG project HE4467/2-1 and the Swiss National Science Foundation (project 200020_126455 ) are gratefully acknowledged.

PY - 2013

Y1 - 2013

N2 - Changes in terrestrial vegetation patterns during the Valanginian (Early Cretaceous) and their link to major climatic and environmental alterations are poorly studied. In this study, the spatial and temporal changes in plant community structure are reconstructed based on spore-pollen records from two mid-latitude sites located in the Mid-Polish Trough (MPT, central Poland), and the Vocontian Basin (VB, southeast France). Stratigraphic control is provided by δ13Ccarb chemostratigraphy and calcareous nannofossil biostratigraphy. Reconstruction of hinterland vegetation is based on palynological investigations of 83 samples from hemipelagic (VB) and marginal marine (MPT) sediments rich in terrestrial palynomorphs. A total of 45 palynomorph taxa were identified at generic level (30 spores, 15 pollen). Vegetation around the MPT was dominated by araucarian/cupressacean conifers while that surrounding the VB was dominated by drought-resistant cheirolepidiacean conifers. At both sites the understorey and/or vegetation of open areas was dominated by pteridophytes. An early Valanginian gradual trend towards humid conditions at the MPT, well expressed by a distinct increase in the spore-pollen ratio, culminates in a short-lived spore-maximum stratigraphically located at the lower/upper Valanginian boundary. It is characterized by low conifer abundances and high abundances of the fern spore taxa Cyathidites, Leiotriletes and Gleicheniidites accompanied by enhanced abundances of the pteridosperm pollen Vitreisporites pallidus, whose parent plants are assumed to be indicative of swamp habitats. The spore-maximum is coeval to a similar peak observed in the VB, characterized by essentially the same taxa. Here, the spore-maximum is preceded by a protracted phase of arid conditions, characterized by low spore abundances and exceptionally high numbers of the cheirolepidiacean conifer pollen Classopollis. Changes in moisture, identified as the key climatic factor determining trends and turnovers in vegetation, were probably controlled by a monsoonal circulation. The supra-regional humid phase expressed by the coeval spore maxima was probably induced by an intensified monsoonal climate. The temporal influence of a northern hemisphere arid belt at the VB, under the influence of the subtropical high-pressure belt, may have caused the temporal drying not affecting the MPT site, located further north.

AB - Changes in terrestrial vegetation patterns during the Valanginian (Early Cretaceous) and their link to major climatic and environmental alterations are poorly studied. In this study, the spatial and temporal changes in plant community structure are reconstructed based on spore-pollen records from two mid-latitude sites located in the Mid-Polish Trough (MPT, central Poland), and the Vocontian Basin (VB, southeast France). Stratigraphic control is provided by δ13Ccarb chemostratigraphy and calcareous nannofossil biostratigraphy. Reconstruction of hinterland vegetation is based on palynological investigations of 83 samples from hemipelagic (VB) and marginal marine (MPT) sediments rich in terrestrial palynomorphs. A total of 45 palynomorph taxa were identified at generic level (30 spores, 15 pollen). Vegetation around the MPT was dominated by araucarian/cupressacean conifers while that surrounding the VB was dominated by drought-resistant cheirolepidiacean conifers. At both sites the understorey and/or vegetation of open areas was dominated by pteridophytes. An early Valanginian gradual trend towards humid conditions at the MPT, well expressed by a distinct increase in the spore-pollen ratio, culminates in a short-lived spore-maximum stratigraphically located at the lower/upper Valanginian boundary. It is characterized by low conifer abundances and high abundances of the fern spore taxa Cyathidites, Leiotriletes and Gleicheniidites accompanied by enhanced abundances of the pteridosperm pollen Vitreisporites pallidus, whose parent plants are assumed to be indicative of swamp habitats. The spore-maximum is coeval to a similar peak observed in the VB, characterized by essentially the same taxa. Here, the spore-maximum is preceded by a protracted phase of arid conditions, characterized by low spore abundances and exceptionally high numbers of the cheirolepidiacean conifer pollen Classopollis. Changes in moisture, identified as the key climatic factor determining trends and turnovers in vegetation, were probably controlled by a monsoonal circulation. The supra-regional humid phase expressed by the coeval spore maxima was probably induced by an intensified monsoonal climate. The temporal influence of a northern hemisphere arid belt at the VB, under the influence of the subtropical high-pressure belt, may have caused the temporal drying not affecting the MPT site, located further north.

KW - δC chemostratigraphy

KW - Early Cretaceous

KW - Nannofossil biostratigraphy

KW - Paleoclimate

KW - Valanginian palynology

KW - Vegetation

UR - http://www.scopus.com/inward/record.url?scp=84879594819&partnerID=8YFLogxK

U2 - 10.1016/j.revpalbo.2013.05.003

DO - 10.1016/j.revpalbo.2013.05.003

M3 - Article

AN - SCOPUS:84879594819

VL - 197

SP - 50

EP - 69

JO - Review of Palaeobotany and Palynology

JF - Review of Palaeobotany and Palynology

SN - 0034-6667

ER -