TY - JOUR

T1 - Climatic evolution across oceanic anoxic event 1a derived from terrestrial palynology and clay minerals (Maestrat Basin, Spain)

AU - Cors, Jean

AU - Heimhofer, Ulrich

AU - Adatte, Thierry

AU - Hochuli, Peter A.

AU - Huck, Stefan

AU - Bover-Arnal, Telm

PY - 2015/7/4

Y1 - 2015/7/4

N2 - Studies dealing with the response of the continental biosphere to the environmental perturbations associated with Cretaceous oceanic anoxic events (OAEs) are comparatively rare. Here, a quantitative spore-pollen record combined with clay mineral data is presented, which covers the entire early Aptian OAE 1a interval (Forcall Formation, Maestrat basin, east Spain). The well-expressed OAE 1a carbon-isotope anomaly is paralleled by changes in the clay mineral assemblage and by a stepwise decline in the normalized frequency of Classopollis pollen (produced by xerophytic Cheirolepidiaceae) with lowest contents occurring during the positive δ13C shift. In contrast, Araucariacites and Inaperturopollenites pollen show a pronounced increase in relative abundance from low background values to become a significant component of the palynological assemblage during the Classopollis minimum. The observed changes in clay minerals and pollen distribution patterns are interpreted to reflect a major change in the composition of the hinterland vegetation of the Maestrat Basin, most probably due to short-lived but pronounced climatic cooling and changes in humidity. Temperature anomalies driven by organic carbon burial and associated CO2 decline have been postulated for all major Mesozoic OAEs. The palynomorph record from the Iberian Maestrat basins indicates that the climax of this cooling episode was significantly delayed in comparison to the end of organic carbon-rich deposition in the world oceans.

AB - Studies dealing with the response of the continental biosphere to the environmental perturbations associated with Cretaceous oceanic anoxic events (OAEs) are comparatively rare. Here, a quantitative spore-pollen record combined with clay mineral data is presented, which covers the entire early Aptian OAE 1a interval (Forcall Formation, Maestrat basin, east Spain). The well-expressed OAE 1a carbon-isotope anomaly is paralleled by changes in the clay mineral assemblage and by a stepwise decline in the normalized frequency of Classopollis pollen (produced by xerophytic Cheirolepidiaceae) with lowest contents occurring during the positive δ13C shift. In contrast, Araucariacites and Inaperturopollenites pollen show a pronounced increase in relative abundance from low background values to become a significant component of the palynological assemblage during the Classopollis minimum. The observed changes in clay minerals and pollen distribution patterns are interpreted to reflect a major change in the composition of the hinterland vegetation of the Maestrat Basin, most probably due to short-lived but pronounced climatic cooling and changes in humidity. Temperature anomalies driven by organic carbon burial and associated CO2 decline have been postulated for all major Mesozoic OAEs. The palynomorph record from the Iberian Maestrat basins indicates that the climax of this cooling episode was significantly delayed in comparison to the end of organic carbon-rich deposition in the world oceans.

KW - clay minerals

KW - early Aptian

KW - Maestrat Basin

KW - oceanic anoxic event 1a

KW - palynology

UR - http://www.scopus.com/inward/record.url?scp=84937643946&partnerID=8YFLogxK

U2 - 10.1017/S0016756814000557

DO - 10.1017/S0016756814000557

M3 - Article

AN - SCOPUS:84937643946

VL - 152

SP - 632

EP - 647

JO - Geological magazine

JF - Geological magazine

SN - 0016-7568

IS - 4

ER -