Palaeoclimatic implications of high-resolution clay mineral assemblages preceding and across the onset of the Palaeocene–Eocene Thermal Maximum, North Sea Basin

Abstract

A B S T R AC T : Understanding the composition of clay-rich sediments and their transportation into proximal marine basins allows us to better decipher hydroclimatic changes before and within the Palaeocene-Eocene Thermal Maximum (PETM). Only a limited number of such studies exists from the North Sea Basin, which was proximal to the volcanic activity and early rifting hypothesized to have triggered the PETM. The present study examines core material from well 22/10a-4, UK North Sea, as it exhibits an exceptionally expanded and almost stratigraphically complete fine-grained sedimentary sequence suitable for high-resolution analysis.Quantitative Newmod-for-Windows™-modelled clay mineral assemblages, rather than traditional semi-quantitative estimates, are dominated by smectite-rich, interlayered illite-smectite that probably developed from volcanogenic deposits on continental landmasses. Soil development before the PETM is consistent with the existence of a seasonal tropical climate with a prolonged dry season. A striking rise and fall of kaolinite content within the PETM onset, prior to the principal carbon-isotope excursion, is reported here. This variation is interpreted as a signal of an enhanced hydrologic cycle producing an increase in erosionally derived kaolinite, followed by a dampening of this detrital source as sea-levels rose. Global variations in PETM kaolinite concentrations are consistent with a latitudinal shift in patterns of precipitation in models of global warming.

Constraints on Earth System Functioning at the Paleocene‐Eocene Thermal Maximum From the Marine Silicon Cycle

“…A second line of evidence put forward for enhanced silicate weathering during the PETM is the observation that kaolinite—a clay mineral devoid of cations and indicative of intense weathering—is found in greater abundance in PETM aged deposits than pre‐ or post‐event. Localities with increased kaolinite include the north east American margin (Gibson et al, 2000; John et al, 2012), the North Sea (Kemp et al, 2016), the Basque Basin (Schmitz et al, 2001), the Tethys (Bolle & Adatte, 2001), and Antarctica (Robert & Kennett, 1994). However, there is a strong argument that clay mineralogy is insensitive to millennial‐scale climate change (Frings, 2019; Thiry & Dupuis, 2000) because kaolinite‐rich soil formation rates are slow.…”

Late Miocene Intensified Tectonic Uplift and Climatic Aridification on the Northeastern Tibetan Plateau: Evidence From Clay Mineralogical and Geochemical Records in the Xining Basin

“…As a result, chlorite and illite can be considered as characteristic of early weathering, while smectite and kaolinite are products of intermediate and late stages of weathering, respectively. Based on this, clay mineral assemblages, such as (kaolinite+smectite)/(illite+chlorite) and smectite/illite, are excellent indicators for tracing the weathering and climate of a source area (e.g., Bouquillon et al, ; Kemp et al, ; Z. F. Liu et al, ; Shen et al, ; Thiry, ). However, in our study, the increase in the kaolinite content may be derived from detrital input from old sedimentary sequences in the catchment.…”

Decoding the origins and sources of clay minerals in the Upper Cretaceous Tununk Shale of south‐central Utah: Implications for the pursuit of climate and burial histories

“…Clay mineralogy has been widely used as a proxy for quantifying the intensity of continental weathering and reconstructing palaeoclimate (Singer, 1984;Dera et al, 2009;Kemp et al, 2016;Wendler et al, 2016). The most important underlying assumption for this approach is that the clay minerals in a given sedimentary succession are derived mainly from coeval soils and thus directly reflect climate parameters (weathering conditions) in the hinterland (Biscaye, 1965;Singer, 1984;Chamley, 1989;Thiry, 2000;Junttila et al, 2005;Wendler et al, 2016).…”

“…It can for example be derived from various older shale/mudstone successions in the hinterland, an interpretation that is consistent with the presence of shale lithics in the Tununk Shale. Other possible sources for the mixed-layer I/S are soil profiles developed on older volcanic rocks and weathering of volcanic debris that fell on land areas and underwent repeated wetting and drying episodes (Hein and Scholl, 1978;Schultz, 1978;Eberl et al, 1987;Kemp et al, 2016). In XRD patterns from the Tununk shale samples, the symmetrical peak at ~10 Å indicates the presence of mica instead of discrete illite in the <2 μm fractions (Środoń, 1981).…”

“…This is because clay minerals in marine sediments were generally assumed to be inherited from landmasses via weathering of bedrock, which is ultimately controlled by climate (Biscaye, 1965;Chamley, 1989;Hallam et al, 1991;Junttila et al, 2005;Dera et al, 2009;Liu et al, 2010;Wendler et al, 2016). The other underlying assumption for using clays as palaeoclimate proxies is that sedimentary clay mineral assemblages have not been altered significantly by diagenetic processes (Singer, 1984;Curtis, 1990;Ruffel et al, 2002;Kemp et al, 2016;Xu et al, 2017).…”