TY - JOUR

T1 - Using high-resolution XRF analyses as a sequence stratigraphic tool in a mudstone-dominated succession (Early Cretaceous, Lower Saxony Basin, Northern Germany)

AU - Thöle, Hauke

AU - Bornemann, André

AU - Heimhofer, Ulrich

AU - Luppold, Friedrich Wilhelm

AU - Blumenberg, Martin

AU - Dohrmann, Reiner

AU - Erbacher, Jochen

N1 - Funding information: This research has been funded by the Federal Institute for Geosciences and Natural Resources (BGR) in the framework of the project ‘Subsurface Potentials for Storage and Economic Use in the North German Basin (TUNB)'. T. Kollaske is thanked for her support during XRF?CS, G. Grützner and S. Stäger for sample preparation (all BGR). We further thank two anonymous reviewers for their insightful and constructive comments.

PY - 2020/2/5

Y1 - 2020/2/5

N2 - Delineation of stratigraphic sequences and their component systems tracts in mudstone-dominated successions is challenging due to the relatively homogenous, fine-grained nature of the strata. High-resolution elemental intensity data from X-ray fluorescence core scanning is used in order to develop a sequence stratigraphic framework for the Lower Cretaceous monotonous mudstone succession in the eastern Lower Saxony Basin. The study is based on four drill cores covering the Berriasian to Aptian interval. In addition, carbon isotope (δ13Corg), grain size and CaCO3 analyses were carried out on discrete samples. The studied cores represent both proximal and distal basinal environments of the eastern Lower Saxony Basin and can be reliably correlated by utilizing variations in selected X-ray flourescence elemental ratios, K/Ti data have proven to be particularly suitable in this regard. The core correlation shows that chemostratigraphic variability within the studied succession is laterally reproducible in the eastern Lower Saxony Basin, and can be used to establish a sequence stratigraphic framework. Further, Si/Al and Ca/Ti ratios have been applied to characterize the cores in terms of variation in grain size and CaCO3 content, respectively. Vertical grading trends inferred from Si/Al changes were used to identify transgressive and regressive systems tracts within the studied succession. An important regression in the uppermost lower Valanginian coincides with the onset of the Valanginian Weissert Event, as indicated by the well-known positive δ13C shift, and, thus, supports the idea that the initial interval of this event corresponds to enhanced supply of terrigenous material. The results of this study are also in agreement with previously recognized transgressive–regressive trends in the Lower Saxony Basin and adjacent areas. This clearly shows that systematic geochemical variations recorded in mudstone-dominated basinal settings are suitable to establish sequence stratigraphic frameworks.

AB - Delineation of stratigraphic sequences and their component systems tracts in mudstone-dominated successions is challenging due to the relatively homogenous, fine-grained nature of the strata. High-resolution elemental intensity data from X-ray fluorescence core scanning is used in order to develop a sequence stratigraphic framework for the Lower Cretaceous monotonous mudstone succession in the eastern Lower Saxony Basin. The study is based on four drill cores covering the Berriasian to Aptian interval. In addition, carbon isotope (δ13Corg), grain size and CaCO3 analyses were carried out on discrete samples. The studied cores represent both proximal and distal basinal environments of the eastern Lower Saxony Basin and can be reliably correlated by utilizing variations in selected X-ray flourescence elemental ratios, K/Ti data have proven to be particularly suitable in this regard. The core correlation shows that chemostratigraphic variability within the studied succession is laterally reproducible in the eastern Lower Saxony Basin, and can be used to establish a sequence stratigraphic framework. Further, Si/Al and Ca/Ti ratios have been applied to characterize the cores in terms of variation in grain size and CaCO3 content, respectively. Vertical grading trends inferred from Si/Al changes were used to identify transgressive and regressive systems tracts within the studied succession. An important regression in the uppermost lower Valanginian coincides with the onset of the Valanginian Weissert Event, as indicated by the well-known positive δ13C shift, and, thus, supports the idea that the initial interval of this event corresponds to enhanced supply of terrigenous material. The results of this study are also in agreement with previously recognized transgressive–regressive trends in the Lower Saxony Basin and adjacent areas. This clearly shows that systematic geochemical variations recorded in mudstone-dominated basinal settings are suitable to establish sequence stratigraphic frameworks.

KW - Lower Cretaceous

KW - Lower Saxony Basin

KW - mudstones

KW - sequence stratigraphy

KW - Weissert Event

KW - X-ray fluorescence core scanning

UR - http://www.scopus.com/inward/record.url?scp=85086585708&partnerID=8YFLogxK

U2 - 10.1002/dep2.83

DO - 10.1002/dep2.83

M3 - Article

AN - SCOPUS:85086585708

VL - 6

SP - 236

EP - 258

JO - The Depositional Record

JF - The Depositional Record

SN - 2055-4877

IS - 1

ER -