TY - JOUR

T1 - Palynology of the Triassic–Jurassic transition of the Danish Basin (Denmark)

T2 - a palynostratigraphic zonation of the Gassum–lower Fjerritslev formations

AU - Lindström, Sofie

AU - Pedersen, Gunver Krarup

AU - Vosgerau, Henrik

AU - Hovikoski, Jussi

AU - Dybkjær, Karen

AU - Nielsen, Lars Henrik

PY - 2023

Y1 - 2023

N2 - The Upper Triassic–Lower Jurassic succession in the Danish Basin is penetrated by many deep wells that were drilled during former hydrocarbon exploration campaignes but it is today targeted for geothermal energy and storage of CO2. In the Stenlille salt dome on Sjælland sandstones of the Gassum Formation, sealed by the overlying Fjerritslev Formation mudstones, have been used for decades as a seasonal storage for natural gas. With its comprehensive dataset of seismics, geophysical well logs and conventional core data from twenty wells, the Stenlille succession serves as a model for other salt domes currently evaluated as potential CO2 storage sites in the basins. Over the last decade the cored Triassic–Jurassic boundary (TJB) succession has contributed to the understanding of environmental and palynological events during the end-Triassic mass extinction. Core, sidewall core and cuttings samples from several of the closely situated Stenlille wells are here used for establishment of a high-resolution palynostratigraphic zonation scheme covering the entire Rhaetian to Sinemurian succession by integrating new analyses with previously published data. The palynological data set have allowed recognition of nine formally described spore-pollen zones of which eight are new, while two previously described dinoflagellate cysts zones are subdivided into 3 informal subzones each. The palynological zonation is integrated with a sequence stratigraphic framework and will form the basis for the dating of future well sections in the Danish Basin as well as other basins and for correlation to outcrops. The large palynological dataset further shows that the vegetation around the Danish Basin was remarkably stable during the early to middle Rhaetian, but that events related to the emplacement of the Central Atlantic Magmatic Province accelerated ecosystem changes during c. 175 kyrs in the late Rhaetian and earliest Hettangian including ~25 kyrs of successional recovery before the terrestrial ecosystem had again stabilized.

AB - The Upper Triassic–Lower Jurassic succession in the Danish Basin is penetrated by many deep wells that were drilled during former hydrocarbon exploration campaignes but it is today targeted for geothermal energy and storage of CO2. In the Stenlille salt dome on Sjælland sandstones of the Gassum Formation, sealed by the overlying Fjerritslev Formation mudstones, have been used for decades as a seasonal storage for natural gas. With its comprehensive dataset of seismics, geophysical well logs and conventional core data from twenty wells, the Stenlille succession serves as a model for other salt domes currently evaluated as potential CO2 storage sites in the basins. Over the last decade the cored Triassic–Jurassic boundary (TJB) succession has contributed to the understanding of environmental and palynological events during the end-Triassic mass extinction. Core, sidewall core and cuttings samples from several of the closely situated Stenlille wells are here used for establishment of a high-resolution palynostratigraphic zonation scheme covering the entire Rhaetian to Sinemurian succession by integrating new analyses with previously published data. The palynological data set have allowed recognition of nine formally described spore-pollen zones of which eight are new, while two previously described dinoflagellate cysts zones are subdivided into 3 informal subzones each. The palynological zonation is integrated with a sequence stratigraphic framework and will form the basis for the dating of future well sections in the Danish Basin as well as other basins and for correlation to outcrops. The large palynological dataset further shows that the vegetation around the Danish Basin was remarkably stable during the early to middle Rhaetian, but that events related to the emplacement of the Central Atlantic Magmatic Province accelerated ecosystem changes during c. 175 kyrs in the late Rhaetian and earliest Hettangian including ~25 kyrs of successional recovery before the terrestrial ecosystem had again stabilized.

KW - Faculty of Science

KW - Triassic

KW - Jurassic

KW - Palynology

KW - biostratigraphy

KW - sequence stratigraphy

KW - spores

KW - pollen

KW - dinoflagellate cysts

KW - mass extinction

U2 - 10.1080/01916122.2023.2241068

DO - 10.1080/01916122.2023.2241068

M3 - Journal article

VL - 47

JO - Palynology

JF - Palynology

SN - 0191-6122

IS - 4

M1 - 2241068

ER -