TY - GEN
T1 - Revisiting the Cretaceous normal superchron in the SW Indian Ocean
AU - Dyment, Jerome
AU - Gallet, Yves
AU - Granot, Roi
AU - Seama, Nobukazu
AU - Poitou, Charles
AU - Okino, Kyoto
AU - Sato, Taichi
AU - Choe, Hanjin
AU - Pasenko, Aleksandr
AU - Phua, Marcus
AU - Roth, Shai
AU - Zhang, Tao
AU - Hemond, Christophe
AU - Blanc, Mathieu
AU - Kraus, Erez
AU - Makuzeni, Manyano
AU - Raifman, Gad
AU - Razafimamonjy, Volanirina S.
AU - Schatz, Assa
AU - Resseguier, Frederic
N1 - Accession Number: 2019-028808; Conference Name: American Geophysical Union 2017 fall meeting; New Orleans, LA, United States; Conference Date: 20171211; Language: English; Coden: #07548; Collation: Abstract DI32A-06; Publication Types: Serial; Conference; Abstract Only; Updated Code: 201916; Monograph Title: AGU 2017 fall meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic
PY - 2017
Y1 - 2017
N2 - The Cretaceous Normal Superchron (CNS) is a approximately 40 Myr-long period of constant normal geomagnetic polarity during which no geomagnetic reversal has been convincingly observed so far. It extended from Chron M0 (approximately 120 Ma) to Chron 34 (83 Ma). In a previous study we showed that significant differences in the variability of the geomagnetic dipole moment exist within the CNS, with long wavelength, low amplitude variations in its first third, short wavelength, high amplitude variations within the median third, and long wavelength, very low amplitude variations in the last third (Granot et al., Nature Geoscience, 2012). We also demonstrated the existence of markers that can be identified within the CNS and allow intermediate plate reconstructions between Chrons M0 and 34 (Granot & Dyment, EPSL, 2015). Our inspection of a global set of marine magnetic profiles suggested that the Mozambique Basin and its conjugate off Antarctica may host the best records of the CNS. We therefore carried out project Magofond 4, a two leg-expedition (January-March 2017) in this area to better constrain (1) the variability in magnetic dipole moment, the possible occurrence of short reversed polarity intervals, and more generally the evolution of the geodynamo during, immediately before and after the CNS, and (2) the presence of markers allowing detailed reconstructions of the Antarctic and African Plates within the CNS. During Leg 1 onboard R/V Pourquoi pas?, we acquired a long deep tow, high-resolution magnetic profile across the median part of the CNS, a shorter profile across Chron 33r, and three sea-surface magnetic profiles across the CNS in the Mozambique Basin. During Leg 2 onboard R/V Marion Dufresne, we acquired four sea-surface magnetic profiles across the CNS in the Riiser-Larsen Sea. A sea-surface vector magnetometer and two scalar magnetometers (gradiometer) were used during half of Leg 2. During both legs we collected (almost) continuously shipboard three-component magnetics, multibeam bathymetry and imagery, sub-bottom profiler data, and gravity. Best use was made of the transits to acquire valuable data across the SWIR. We will present the cruise, the data, and some initial results.
AB - The Cretaceous Normal Superchron (CNS) is a approximately 40 Myr-long period of constant normal geomagnetic polarity during which no geomagnetic reversal has been convincingly observed so far. It extended from Chron M0 (approximately 120 Ma) to Chron 34 (83 Ma). In a previous study we showed that significant differences in the variability of the geomagnetic dipole moment exist within the CNS, with long wavelength, low amplitude variations in its first third, short wavelength, high amplitude variations within the median third, and long wavelength, very low amplitude variations in the last third (Granot et al., Nature Geoscience, 2012). We also demonstrated the existence of markers that can be identified within the CNS and allow intermediate plate reconstructions between Chrons M0 and 34 (Granot & Dyment, EPSL, 2015). Our inspection of a global set of marine magnetic profiles suggested that the Mozambique Basin and its conjugate off Antarctica may host the best records of the CNS. We therefore carried out project Magofond 4, a two leg-expedition (January-March 2017) in this area to better constrain (1) the variability in magnetic dipole moment, the possible occurrence of short reversed polarity intervals, and more generally the evolution of the geodynamo during, immediately before and after the CNS, and (2) the presence of markers allowing detailed reconstructions of the Antarctic and African Plates within the CNS. During Leg 1 onboard R/V Pourquoi pas?, we acquired a long deep tow, high-resolution magnetic profile across the median part of the CNS, a shorter profile across Chron 33r, and three sea-surface magnetic profiles across the CNS in the Mozambique Basin. During Leg 2 onboard R/V Marion Dufresne, we acquired four sea-surface magnetic profiles across the CNS in the Riiser-Larsen Sea. A sea-surface vector magnetometer and two scalar magnetometers (gradiometer) were used during half of Leg 2. During both legs we collected (almost) continuously shipboard three-component magnetics, multibeam bathymetry and imagery, sub-bottom profiler data, and gravity. Best use was made of the transits to acquire valuable data across the SWIR. We will present the cruise, the data, and some initial results.
KW - Stratigraphy; 12
M3 - Conference contribution
SP - DI32A-06
BT - American Geophysical Union, Fall Meeting 2017
ER -