X-Ray Mineralogy and Mineral Geochemistry of Cenozoic Strata (Leg 80) and Petrographic Study of Associated Pebbles

Chennaux, G.; Esquevin, Jacques; Jourdan, A.; Latouche, C.; Maillet, N.

doi:10.2973/dsdp.proc.80.148.1985

Cited by 10 publications

(4 citation statements)

References 13 publications

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“…Interestingly, the opportunistic planktic foraminifer Chiloguembelina first appeared in large numbers at the onset of the PETM at Site 401 [ Pardo et al ., ; D ' haenens et al ., ], only to permanently disappear concurrent with ETM2 (Figure ). Although no direct evidence for a long‐term hydrological change associated with the ETM2 is observed in the NE Atlantic (e.g., the long‐term clay mineralogical assemblages remain relatively stable in the region [ Cassat , ; Chennaux et al ., ]), we suspect that, by analogy with the PETM, a regionally weakened hydrological cycle may be (partially) responsible for the observed sedimentological patterns.…”

Section: Discussionmentioning

confidence: 99%

A transient deep‐sea circulation switch during Eocene Thermal Maximum 2

et al. 2014

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Ever since its discovery, Eocene Thermal Maximum 2 (ETM2;~53.7 Ma) has been considered as one of the "little brothers" of the Paleocene-Eocene Thermal Maximum (PETM;~56 Ma) as it displays similar characteristics including abrupt warming, ocean acidification, and biotic shifts. One of the remaining key questions is what effect these lesser climate perturbations had on ocean circulation and ventilation and, ultimately, biotic disruptions. Here we characterize ETM2 sections of the NE Atlantic (Deep Sea Drilling Project Sites 401 and 550) using multispecies benthic foraminiferal stable isotopes, grain size analysis, XRF core scanning, and carbonate content. The magnitude of the carbon isotope excursion (0.85-1.10‰) and bottom water warming (2-2.5°C) during ETM2 seems slightly smaller than in South Atlantic records. The comparison of the lateral δ 13 C gradient between the North and South Atlantic reveals that a transient circulation switch took place during ETM2, a similar pattern as observed for the PETM. New grain size and published faunal data support this hypothesis by indicating a reduction in deepwater current velocity. Following ETM2, we record a distinct intensification of bottom water currents influencing Atlantic carbonate accumulation and biotic communities, while a dramatic and persistent clay reduction hints at a weakening of the regional hydrological cycle. Our findings highlight the similarities and differences between the PETM and ETM2. Moreover, the heterogeneity of hyperthermal expression emphasizes the need to specifically characterize each hyperthermal event and its background conditions to minimalize artifacts in global climate and carbonate burial models for the early Paleogene.

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Section: Discussionmentioning

confidence: 99%

A transient deep‐sea circulation switch during Eocene Thermal Maximum 2

et al. 2014

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“…This study focuses on the top 40 m of DSDP Core 548, consisting of alternations of Pleistocene to Holocene marly ooze and mud (Chennaux et al . 1985; De Graciansky et al . 1985).…”

Section: Settingmentioning

confidence: 99%

“…The downhole wireline logging was conducted at Site 548A (48°54.93 0 N, 12°09.87 0 W), 30 m west of the cored section. This study focuses on the top 40 m of DSDP Core 548, consisting of alternations of Pleistocene to Holocene marly ooze and mud (Chennaux et al 1985;De Graciansky et al 1985). Preliminary biostratigraphy indicates a Pleistocene age for Unit 1 overlain by 28 cm of Holocene unlithified brown mud (De Graciansky et al 1985).…”

Section: Settingmentioning

confidence: 99%

British–Irish Ice Sheet and polar front history of the Goban Spur, offshore southwest Ireland over the last 250 000 years

Fabian,

Gallagher,

De Vleeschouwer

2023

Boreas

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Deep Sea Drilling Program (DSDP) Site 548 was cored in 1984 at a water depth of 1256 m on the Goban Spur, offshore southwest Ireland. Coring retrieved a ~100‐m‐thick Pleistocene contourite sequence. This study uses planktonic foraminiferal assemblage and benthic foraminiferal oxygen isotope analyses to establish an age model for the upper 40 m of this core. This site's multidisciplinary analyses of planktonic foraminiferal assemblages, lithic grains, facies and calcium carbonate concentration reveal a 250 000‐year record of the North Atlantic polar front variability and British–Irish Ice Sheet (BIIS) history. The sequence is characterized by alternations of ice rafted debris (IRD) laden pelagic mud facies with calcium carbonate‐rich silty sand contourite facies that track glacial/interglacial cycles. The polar front migrated southward across the area several times during glacial maxima and stadial periods, while warmer Mediterranean Outflow Water (MOW) flowed northward across the region during interglacial and interstadial periods depositing contourites. Lithic analyses reveal a complex history of IRD deposition associated with iceberg calving from the Laurentide Ice Sheet and northwest European ice sheets, mainly the BIIS. Comparison between the Goban Spur (DSDP Site 548) and the Celtic Margin (MD03‐2692) and central North Atlantic Integrated Ocean Drilling Program (IODP) Site U1308 suggests differences between the ‘non‐Laurentide Ice Sheet’ Heinrich Events (HE) 6 and 3 at the Goban Spur, with IRD from the BIIS being prominent during HE 6 and IRD from other European ice sheets north of the BIIS likely being more dominant during HE 3. The nature of lithics in IRD‐rich horizons during Terminations 3, 3A, 2 and 1 suggests significant iceberg calving episodes preceding BIIS retreat during the onset of interstadial intervals.

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“…These analyses may provide information about the source of detrital minerals, the type of climate prevailing at the time of the formation, and determine the oceanic currents responsible for their transport and settling. This type of investigation has already been applied to a large number of Atlantic DSDP sites (Melieres 1977;Chamley and Robert 1979;Maillet 1979, 1984;Froget 1981;Robert 1982;and Chennaux et al, 1984). Results presented here are compared with those obtained from neighboring drilled sites (DSDP Legs 38, 48B, and 81).…”

Section: Introductionmentioning

confidence: 99%

Paleoenvironmental Significance of Cenozoic Clay Deposits from the Norwegian Sea: ODP Leg 104

Froget¹,

Desprairies²,

Latouche³

et al. 1989

Proceedings of the Ocean Drilling Program

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The mineralogical and geochemical study of samples from Sites 642, 643, and 644 enabled us to reconstruct several aspects of the Cenozoic paleoenvironmental evolution (namely volcanism, climate, hydrology) south of the Norwegian Sea and correlate it with evolution trends in the northeast Atlantic. Weathering products of early Paleogene volcanic material at Rockall Plateau, over the Faeroe-Iceland Ridge and the Vdring Plateau indicate a hot and moist climate (lateritic environment) existed then. From Eocene to Oligocene, mineralogical assemblages of terrigenous sediments suggest the existence of a warm but somewhat less moist climate at that time than during the early Paleogene. At the beginning of early Miocene, climatic conditions were warm and damp. The large amounts of amorphous silica in Miocene sediment could indicate an important flux of silica from the continent then, or suggest the formation of upwelling. Uppermost lower Miocene and middle to upper Miocene clay assemblages suggest progressive cooling of the climate from warm to temperate at that time. At the end of early Miocene, hydrological exchanges between the North Atlantic and the Norwegian Sea became intense and gave rise to an important change in the mineralogy of deposits. From Pliocene to Pleistocene, the variable mineralogy of deposits reflects alternating glacial/interglacial climatic episodes, a phenomenon observed throughout the North Atlantic.

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X-Ray Mineralogy and Mineral Geochemistry of Cenozoic Strata (Leg 80) and Petrographic Study of Associated Pebbles

Cited by 10 publications

References 13 publications

A transient deep‐sea circulation switch during Eocene Thermal Maximum 2

A transient deep‐sea circulation switch during Eocene Thermal Maximum 2

British–Irish Ice Sheet and polar front history of the Goban Spur, offshore southwest Ireland over the last 250 000 years

Paleoenvironmental Significance of Cenozoic Clay Deposits from the Norwegian Sea: ODP Leg 104

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