X-Ray Mineralogy from Holes 399, 400, 400A, 401, 402, and 402A of Bay of Biscay

Cassat, G.

doi:10.2973/dsdp.proc.48.127.1979

Cited by 2 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

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

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The change in the mineralogical composition of clays, namely, the replacement of smectites by illites and chlorites, has often been observed in deposits of the second half of the Tertiary in the northeastern Atlantic: Leg 47 (Chamley et al, 1979) and Leg 48 (Cassat, 1979;Latouche and Maillet, 1979). Although it is difficult to give an accurate stratigraphic age to this event (because of numerous sedimentary gaps that exist between middle Eocene and middle Miocene) the most recent data obtained during Leg 80 (Chennaux et al, unpublished) locate the major mineralogical change in clays at the middle/upper Miocene boundary.…”

Section: Mineralogical Unitmentioning

confidence: 99%

X-Ray Mineralogy Study of Tertiary Deposits, Leg 81, Sites 552555

Latouche¹

1984

Initial Reports of the Deep Sea Drilling Project

View full text Add to dashboard Cite

This X-ray mineralogy study of Tertiary samples recovered from Rockall sites permitted the definition of four mineralogical units and the tracing of the paleoenvironmental evolution in this region. INTRODUCTION The following mineralogical units were defined on the basis of our study: Unit I (upper Paleocene) is characterized by the occurrence of quartz and feldspars as well as by that of clay minerals, namely smectite, illite, kaolinite, and chlorite. Deposits are of a quite marked detrital nature. Unit II (lower Eocene) consists of sediments represented by plagioclase feldspars and zeolites; the major clay mineral components are smectites. These deposits suggest a sedimentation influenced by a basic volcanic environment. The presence of layers rich in kaolinite (Site 555) probably indicates terrigenous inputs developed under leaching warm climates. Unit III (middle Eocene to middle Miocene) is marked by a high carbonate content and dominantly smectite clay minerals: zeolites persist. Sedimentation is of pelagic type attesting to the impact of basic volcanism and/or that of fine-grained terrigenous inputs developed under warm climates with contrasting seasons. Unit IV (from middle/upper Miocene) is also characterized by high carbonate contents. Clay minerals are highly variable (smectite, illite, kaolinite, chlorite). This change in mineralogical composition suggests climatic cooling linked to a change in the hydrological exchanges between the Norwegian Sea and North Atlantic. METHODS Analyses X-ray diffraction was used on a total of 167 Paleocene and Miocene samples. The diffractometer used was a Philips 1310 and operating conditions were as follows: nickle-filtered copper Kα radiation at 40 kv, 20 mA. Total Sediments Dried and pulverized samples of total sediments were analyzed according to the powder diffractogram method. Semiquantitative values of quartz, calcite, and feldspars (K and plagioclase) were estimated from peak heights by comparison with mixed synthetic reference samples. Zeolites were estimated by relative frequencies as abundant, present, or trace on the basis of height of characteristic reflections.

show abstract

X-Ray Mineralogy from Holes 399, 400, 400A, 401, 402, and 402A of Bay of Biscay

Cited by 2 publications

References 0 publications

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

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

X-Ray Mineralogy Study of Tertiary Deposits, Leg 81, Sites 552555

Contact Info

Product

Resources

About

X-Ray Mineralogy from Holes 399, 400, 400A, 401, 402, and 402A of Bay of Biscay

Cited by 2 publications

References 0 publications

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

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

X-Ray Mineralogy Study of Tertiary Deposits, Leg 81, Sites 552555

Contact Info

Product

Resources

About

X-Ray Mineralogy Study of Tertiary Deposits, Leg 81, Sites 552555