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Input of coarse-grained siliciclastics into the Pyrenean Basin during the PETM (2): A river-dominated fan delta within a carbonate platform system
... In addition to the early Toarcian hyperthermal, increased storm intensity associated with global warming has also been observed in other warmer-than-present time intervals in Earth history. For example, there is growing evidence for increased tempestite deposition (30)(31)(32) during the Paleocene Eocene Thermal Maximum (~55 Ma)-an event characterized by a global temperature rise of ~5 to 8 °C (33). An increase in global TC intensity has also been predicted for the Pliocene warm period (~5 to 3 Ma) (34, 35) when the planet warmed by ~3 °C with increased atmospheric CO 2 based on ref. 36. ...
The occurrence of sedimentary storm deposits around the Tethys Ocean during the early Toarcian hyperthermal (~183 Ma) suggests that intensified tropical cyclone (TC) activity occurred in response to CO2 rise and marked warming. However, this hypothesized linkage between extreme warmth and storm activity remains untested, and the spatial pattern of any changes in TCs is unclear. Here, model results show that there were two potential storm genesis centers over Tethys during the early Toarcian hyperthermal located around the northwestern and southeastern Tethys. The empirically determined doubling of CO2 concentration that accompanied the early Toarcian hyperthermal (~500 to ~1,000 ppmv) leads to increased probability of stronger storms over Tethys, in tandem with more favorable conditions for coastal erosion. These results match well with the geological occurrence of storm deposits during the early Toarcian hyperthermal and confirm that increased TC intensity would have accompanied global warming.
... Baceta et al., 2006;Pujalte et al., 2015). The absence of the Mid-Thanetian zones in the KRS-3 section (P4b, most of the C25r) corresponds with unconformity between Th1/Th 2 cycles, which was reflooded during the SBZ 4 Zone to grade up to the Thanetian-Ilerdian carbonate ramps Baceta et al., 2011;Pujalte et al., 2014;Sanders et al., 2019). ...
The Žilina-Hradisko borehole in Slovakia intersects a succession from the Cretaceous Hradisko formation to the Paleocene Hričovské Podhradie formation. In this paper, we mainly focus on the Cretaceous–Palaeogene (K–Pg) boundary interval, which is marked by an abrupt change in planktonic biota and magnetic properties. Micropalaeontological findings suggest a rapid change from a stable, oxygen-rich, oligotrophic environment during the Maastrichtian to an unstable, cooler environment with reduced oxygenation and evidence of biotic stress in the lowermost Danian strata. An abrupt change in the magnetite concentration in the same interval indicates increased detrital input and probably biogenic (soft) magnetite production. Evidence recorded in borehole with enhanced Hg input into the Maastrichtian Ocean suggests that the Deccan eruptions mostly occurred prior to the K–Pg boundary, whereas no volcanic Hg input was detected at the K–Pg boundary itself. Double peaks in multiple magnetic properties mark the Danian hyperthermal Dan-C2 event, which was characterised by a series of environmental changes, including enhanced terrigenous input, oxygen deficit, increased nutrient supply, high benthic productivity, and Parasubbotina acme. Prior to the Latest Danian event, foraminiferal assemblages were significantly affected by dissolution and oxygen depletion, followed by warming, water column stratification, and diversification of calcareous plankton groups. An increase in detrital input and nutrient export drove the productivity of deep-dwelling subbotinids and globanomalinids and were correlated with the mid-Paleocene biotic event (MPBE). The seafloor biota associated with the MPBE implies oxygen deficiency and the prevalence of benthic infauna. The Selandian–Thanetian strata markedly differ from planktonic foraminifera of older formations, with their rich content of large, diversified, and heavily calcified morozovellid and igorinid foraminifera, revealing the existence of water column stratification with surface-water productivity and meso- to oligotrophic conditions. The microfauna of ornate morozovellids and benthic biota from the lowermost formation implies the onset of environmental stress and CaCO3 dissolution during the Paleocene-Eocene Thermal Maximum (PETM).
... Baceta et al., 2006;Pujalte et al., 2015). The absence of the Mid-Thanetian zones in the KRS-3 section (P4b, most of the C25r) corresponds with unconformity between Th1/Th 2 cycles, which was reflooded during the SBZ 4 Zone to grade up to the Thanetian-Ilerdian carbonate ramps Baceta et al., 2011;Pujalte et al., 2014;Sanders et al., 2019). ...
Early Paleogene events of the Alpine Tethys were considerably upgraded for the Western Carpathians. The Kršteňany KRS-3 core section provides high-resolution data from the Cretaceous-Paleogene (K/Pg) transition to Lutetian/Bartonian boundary. The Upper Cretaceous sequence started from terrestrial red-beds superposed by transgressive sediments with Abathomphalus mayaroensis. The K/Pg transition is inferred in a horizon with reworked Maastrichtian microfossils and earliest Danian species of Globigerinidae. Multiple redeposition with eugubina-rich clasts implies a storm erosion and resuspension of the post K/Pg sequence during P0 - Pα Zones (approx. 300 kyr). The early Danian microfauna was initially impoverished, later enriched by first praemuricids, and after the Latest Danian Event (LDE) diversified to angulate morozovellids, igorinids and fasciculiths. Paleocene bioevents and polarity chrons imply a radiation of planktic foraminifera during transgressive cycles in the late Danian (P1, C28n), Middle Selandian (P3b, C26r/n) and late Thanetian (P4c/P5, C25n/C24r), and vacant P/C zones either in regressive cycles or during unconformities in the early Danian (P1a/C28r), Danian/Selandian transition (P2/P3a, C27r/n) and middle Thanetian (P4b/C25r). The late Thanetian transgression (Th-2) led to replacement of Assilina-rich beds (SBZ 4) by Nummulites-bearing marls (SBZ 5) at the base of Illerdian (= LFT). The Paleocene – Eocene transition is marked by Acarinina-rich marlstones with densely muricate species (Ac. acarinata) and excursion taxa (Ac. sibaiyaensis, D. araneus), which correspond to the Paleocene-Eocene Thermal Maximum (PETM). This horizon implies a warm-water productivity, eutrophication, humidity and upwelling activity (pteropods, diatoms). The hyperthermal conditions culminated at the beginning of the Early Eocene Climatic Optimum (EECO) with demise of morozovellids, intensification of hydrological cycles and enhanced continental input of siliciclastics, which progressed by accumulation of Ypresian nummulite banks and terminated by pelagic deposition with recovery of hispid morozovellids (E5 – E7 Zones, chron C23n - C22r). The lower Lutetian sequence reveals a post-EECO cooling by predominance of deep-dwelling habitats (subbotinids, turborotaliids, catapsydracids) and appearance of subtile morozovellids (M. gorrondatxensis), earliest globigerinathekids and another marker species of the E7 – E8 Zones (chron 22n - C21r). Late Lutetian warming (LLTM) is indicated by increased plankton productivity of mixed-layer habitats like strongly muricate species of anguloconical acarininids (Ac. topilensis, Ac. medizzai) and gracile species of morozovelloids (M. coronatus). The youngest part of the Kršteňany section belongs to the E11 Zone, indicating prior conditions of Middle Eocene Climatic Optimum (MECO) warming.
... The PETM coarse-grained siliciclastics of unit B in the incised valleys and of part Z in the deep-sea channel are proof of large increases in, respectively, stream power (which requires greater discharges) and strength and capacity of turbidity currents. PETM coarse-grained sands were also accumulated in a fan delta in the south-central Pyrenees (Fig. 12a, Pujalte et al., 2014b). To evaluate the significance of this influx, however, it must be taken into account that the volume of fine-grained siliciclastics delivered to the Pyrenean Gulf during the PETM far exceeded that of sands and pebbly sands. ...
The Paleocene–Eocene thermal maximum (PETM) is
represented in numerous shallow and deep marine sections of the
south–central and western Pyrenees by a 2–4 m thick unit (locally up to
20 m) of clays or marly clays intercalated within a carbonate-dominated
succession. This unit records a massive input into the Pyrenean Gulf of
fine-grained terrestrial siliciclastics, attributed to an abrupt
hydrological change during the PETM. However, the nature of such a change
remains controversial. Here we show that, in addition to fine-grained
deposits, large volumes of coarse-grained siliciclastics were brought into
the basin and were mostly accumulated in incised valleys and in a long-lived
deep-sea channel. The occurrence of these coarse-grained deposits has been
known for some time, but their correlation with the PETM is reported here
for the first time. The bulk of the incised valley deposits in the PETM
interval are cross-bedded sands and pebbly sands, almost exclusively made of
quartz. The criteria for indicting a relation to the PETM include their
stratigraphic position between upper Thanetian and lower Ilerdian marine
carbonates, organic carbon isotope data, and a high percentage of kaolinite
in the clay matrix. The axially flowing deep-sea channel existed throughout
Paleocene times in the Pyrenean Basin, within which coarse-grained
calciclastic and siliciclastic turbidites were accumulated. This Paleocene
succession is capped by thickly bedded quartz sandstones and pebbly
sandstones, probably deposited by hyperpycnal flows, which are here assigned
to the PETM based on their stratigraphic position and organic carbon
isotopic data. The large and simultaneous increase in coarse- and
fine-grained terrestrial siliciclastics delivered to the Pyrenean Gulf
during the PETM is attributed to an increased intra-annual humidity
gradient. During the PETM a longer and drier summer season facilitated the
erosion of landscapes, whereas a dramatic enhancement of precipitation
extremes during the wet season led to intensified flood events, with rivers
carrying greater volumes of both bed and suspended loads. This scenario
argues against the possibility that PETM kaolinites indicate a coeval warm
and humid climate in northern Spain. Instead, the kaolinite reflects the
erosion of thick Cretaceous lateritic profiles developed on the Hercynian
basement.
... The PETM coarse-grained siliciclastics of unit B in the incised valleys and of part Z in the deep-sea channel are proof of large increases in, respectively, stream power (which requires greater discharges) and strength and capacity of turbidity currents. PETM coarse-grained sands were also accumulated in a fan delta in the south-central Pyrenees (Fig. 12a, Pujalte et al., 2014b). To evaluate the significance of this influx, however, it must be taken into account that the volume of fine-grained siliciclastics delivered to the Pyrenean Gulf during the PETM far exceeded that of sands and pebbly sands. ...
The Paleocene–Eocene thermal maximum (PETM) is represented in numerous shallow and deep marine sections of the south-central and western Pyrenees by a 2–4 m thick unit (locally ca. 20 m) of clays or marly clays intercalated within a carbonate-dominated succession. The massive input of fine-grained terrestrial siliciclastics into the Pyrenean Gulf recorded by that unit has been attributed to an abrupt hydrological change during the PETM. However, the nature of such change remains controversial. Here we show that, in addition to fine-grained deposits, large volumes of coarse-grained siliciclastics were brought into the basin that were mostly accumulated in incised valleys and a long-lived deep-sea channel, both spatially restricted settings. The occurrence of these coarse-grained deposits had been known for some time, but their correlation with the PETM is reported here for the first time. The bulk of incised valley PETM deposits are cross-bedded sands and pebbly sands, almost exclusively made of quartz, currently being actively quarried. Proof of their belonging to the PETM include: (1) their stratigraphic position, sandwiched between upper Thanetian and lower Ilerdian marine carbonates, (2) organic carbon isotope data, and (3) the fact that clay minerals from the sand matrix are more than 80 % kaolinite. The axially-flowing deep-sea channel existed throughout Paleocene times in the Pyrenean Basin, within which coarse-grained calciclastic turbidites, and lesser volumes of siliciclastic turbidites, were accumulated. This Paleocene succession is capped by thick-bedded turbiditic quartz sandstones and pebbly sandstones, here assigned to the PETM based on calcareous nannoplankton, clay mineral and organic carbon isotopic data. The large and simultaneous increase in coarse- and fine-grained terrestrial siliciclastic material delivered to the Pyrenean Gulf is related to an increased intra-annual humidity gradient. During the PETM longer and drier summer seasons facilitated the erosion of landscapes, whereas a dramatic enhancement of precipitation extremes during the wet seasons led to intensified flood events with rivers carrying greater volumes of bed and suspended loads. This scenario argues against the possibility that PETM kaolinites indicate a coeval warm and humid climate in northern Spain. Instead, the erosion of thick Cretaceous lateritic profiles developed in the Hercinian basement is proposed here as the most likely alternative.
... The PETM coarse-grained siliciclastics of unit B in the incised valleys and of part Z in the deep-sea channel are proof of large increases in, respectively, stream power (which requires greater discharges) and strength and capacity of turbidity currents. PETM coarse-grained sands were also accumulated in a fan delta in the south-central Pyrenees (Fig. 12a, Pujalte et al., 2014b). To evaluate the significance of this influx, however, it must be taken into account that the volume of fine-grained siliciclastics delivered to the Pyrenean Gulf during the PETM far exceeded that of sands and pebbly sands. ...
Tropical cyclones are an important meteorological and climatological process in Earth's climate system. These intense, localized storms mainly form over warm equatorial oceans, and propagate poleward. During their lifetime, tropical cyclones can strengthen leading to intense winds and rainfall events. These storms also carry moist energy that contribute to the poleward transport of atmospheric energy. Presently, concern exists about how the characteristics of tropical cyclones will change in a future warming world. The Paleocene Eocene Thermal Maximum (PETM) was a time in Earth's deep past in which the planet warmed by 5° - 8 °C due to an increase in atmospheric CO2. It is thus of interest to understand how past warming affected tropical cyclone behavior. Here, a high resolution (25 km) atmospheric model is used to study changes in tropical cyclones across the PETM boundary. Orbital variation is also investigated as an additional forcing mechanism at the time of the PETM. The climate simulations indicate that greenhouse forcing leads to a poleward shift in TCs, much like projected future scenarios and in simulations of other warm periods in Earth history. It is also found that the orbital forcing response is very different than the greenhouse cases due to the difference in thermal response, which, in turn, induces a different dynamical response in wind shear. Although the spatial pattern between changes across the PETM and the future differ, there are still many similarities in TC response for these two very different periods in time, indicating the robustness of the TC response to greenhouse warming.