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Paleotemperature reconstructions linked to Deccan traps volcanic greenhouse gas emissions and associated feedbacks in the lead-up to the end-Cretaceous meteorite impact and extinction document local and global climate trends during a key interval of geologic history. Here, we present a new clumped-isotope-based paleotemperature record derived from fossil bivalves from the Maastrichtian type region, in southeast Netherlands and northeast Belgium. Clumped isotope data documents a mean temperature of 19.2 ± 3.8 °C, consistent with other Maastrichtian temperature estimates, and an average seawater δ18O value of −0.3 ± 0.9 ‰ VSMOW for the region during the latest Cretaceous (67.1–66.0 Ma). A notable temperature increase at ~66.4 Ma is interpreted to be a regional manifestation of the globally-defined Late Maastrichtian Warming Event, linking Deccan Traps volcanic CO2 emissions prior to the end-Cretaceous extinction to climate change in the Maastricht region. Fluctuating seawater δ18O values coinciding with temperature changes suggest alternating influences of warm, salty southern-sourced waters and cooler, fresher northern-sourced waters from the Arctic Ocean. This new paleotemperature record contributes to the understanding of regional and global climate response to large-scale volcanism and ocean circulation changes leading up to a catastrophic mass extinction.
Paleotemperature reconstructions of the end-Cretaceous interval document local and global climate trends, some driven by greenhouse gas emissions from Deccan Traps volcanism and associated feedbacks. Here, we present a
new clumped-isotope-based paleotemperature record derived from fossil
bivalves from the Maastrichtian type region in southeastern Netherlands and
northeastern Belgium. Clumped isotope data document a mean temperature of 20.4±3.8 ∘C, consistent with other Maastrichtian temperature
estimates, and an average seawater δ18O value of 0.2±0.8 ‰ VSMOW for the region during the latest
Cretaceous (67.1–66.0 Ma). A notable temperature increase at
∼66.4 Ma is interpreted to be a regional manifestation of the
globally defined Late Maastrichtian Warming Event, linking Deccan Traps
volcanic CO2 emissions to climate change in the Maastricht region.
Fluctuating seawater δ18O values coinciding with temperature
changes suggest alternating influences of warm, salty southern-sourced
waters and cooler, fresher northern-sourced waters from the Arctic Ocean.
This new paleotemperature record contributes to the understanding of
regional and global climate response to large-scale volcanism and ocean
circulation changes leading up to a catastrophic mass extinction.
The mid-Maastrichtian carbon isotope event (MME), dated at~69 Ma, reflects a perturbation of the global carbon cycle that, in part, correlates with the enigmatic global extinction of 'true' (i.e., non-tegulated) inoceramid bivalves. The mechanisms of this extinction event are still debated. While both the inoceramid extirpation and MME have been recorded in a variety of deep-sea sites, little is known about their expression in epicontinental chalk seas. In order to study the shallow-marine signature of the MME in this epicontinental shelf sea, we have generated quantitative foraminiferal assemblage data for two quarries (Hallembaye, NE Belgium; ENCI, SE Netherlands) in the Maastrichtian type area, complemented by a species-specific benthic δ 13 C record. In contrast to deep-sea records, no significant changes in benthic foraminiferal assemblages and benthic foraminiferal accumulation rates are observed across the MME in the type-Maastrichtian area. At the Hallembaye quarry, the otherwise rare endobenthic species Cuneus trigona reaches a transient peak abundance of 33.3% at the onset of the MME, likely caused by a local transient change in organic matter flux to the seafloor. Nevertheless, high and near-constant species evenness shows that neither oxygen nor organic matter flux was limited across the extinction level or during the MME. Benthic foraminiferal data from the uppermost part of the studied section, above the MME, indicate a significant increase in food supply to the seafloor. Decreased amounts of terrigenous elements across this interval document a lesser riv-erine or aeolian influx, which means that the increased benthic productivity is linked to a different origin. Potentially, the continuous precipitation of chalk under nutrient-poor conditions in the Late Cretaceous chalk sea was enabled by efficient nutrient recycling in the water column. In shallower depositional settings, nutrient recycling took place closer to the seafloor, which allowed more organic matter to reach the bottom. These results provide insights in the importance of nutrient cycling for biological productivity in the NW-European chalk sea.
The youngest time interval of the Cretaceous Period is known as the Maastrichtian, in reference to the shallow-marine strata outcropping in the area surrounding the city of Maastricht, in the Netherlands- Belgium border region. While the type-Maastrichtian strata have yielded a wealth of paleontological data, comparatively little geochemical work has so far been carried out on this succession. To date, age assessment of the type-Maastrichtian, and stratigraphic correlation with sections elsewhere, have largely been based on biostratigraphy and preliminary attempts at cyclostratigraphy. However, these techniques are hampered by bio-provincialism and the presence of stratigraphic gaps in the succession, respectively. In recent years, stable carbon isotope stratigraphy has proven to be a powerful tool for correlating Upper Cretaceous strata on a global scale. When integrated with biostratigraphy, carbon isotope stratigraphy can be used to test the synchroneity of biological and climatic events across the globe and to reconcile inter-regional biostratigraphic schemes. Therefore, we have generated the first high-resolution bulk stable carbon isotope stratigraphy for the type- Maastrichtian, using an extensive sample set acquired within the context of the Maastrichtian Geoheritage Project spanning approximately 100 meters of stratigraphy at the Hallembaye and former ENCI quarries. In combination with bulk major and trace element data generated using μXRF, this record presents the first high- resolution chemostratigraphic survey for the type-Maastrichtian. The μXRF-based element profiles through the type-Maastrichtian succession reveal variable fluxes of terrigenous input into this carbonate system over time, marking three distinct stratigraphic sequences, separated by sequence boundaries at the Froidmont, Lichtenberg and Vroenhoven horizons. In addition, the carbon isotope profile records the Campanian–Maastrichtian Boundary Event (CMBE) and the Mid-Maastrichtian Event (MME) in the Maastrichtian type area for the first time. Our refined age model allows for global correlation between the type-Maastrichtian sequence and Maastrichtian successions worldwide and places the abundant paleontological records from the type- Maastrichtian in a global context.
