INVESTIGADORES
OLIVERO Eduardo Bernardo
congresos y reuniones científicas
Título:
Santonian-Maastrichtian antarctic ammonites: diversity changes, sedimentary cycles, and paleoceanographic events
Autor/es:
OLIVERO, E. B.
Lugar:
Portland, USA
Reunión:
Congreso; 2009 Portland Geological Society of America Meeting,; 2009
Institución organizadora:
Geological Society of America
Resumen:
The 3-km-thick Santonian-Maastrichtian succession of the James Ross Basin, Antarctica includes three sequences that
record fourteen ammonite associations: the N (Santonian-early Campanian); the NG (late Campanian-early
Maastrichtian); and the MG (early Maastrichtian-Danian) Sequences. The ammonite generic diversification pattern,
particularly kossmaticeratids, is analyzed. The N Sequence has the highest generic richness (S: 24), kossmaticeratids,
mainly Natalites, show an increment by the late early Campanian. Diversity is minimum at the Santonian, then it
increases gradually to an early Campanian maximum, and decreases at the latest early Campanian. Diversity in the NG
Sequence is very peculiar and lower than in the N Sequence. The kossmaticeratids Neograhamites and Gunnarites are
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
increases gradually to an early Campanian maximum, and decreases at the latest early Campanian. Diversity in the NG
Sequence is very peculiar and lower than in the N Sequence. The kossmaticeratids Neograhamites and Gunnarites are
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
increases gradually to an early Campanian maximum, and decreases at the latest early Campanian. Diversity in the NG
Sequence is very peculiar and lower than in the N Sequence. The kossmaticeratids Neograhamites and Gunnarites are
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
Natalites, show an increment by the late early Campanian. Diversity is minimum at the Santonian, then it
increases gradually to an early Campanian maximum, and decreases at the latest early Campanian. Diversity in the NG
Sequence is very peculiar and lower than in the N Sequence. The kossmaticeratids Neograhamites and Gunnarites are
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites and
Neograhamites and Gunnarites are
dominant, representing more than 50% of the total abundance. The NG Sequence has the highest kossmaticeratid
richness, which is approximately constant with S close to 10. The MG Sequence diversity curve is similar to that of the
previous one but has a lowered richness (S: 5-8) and an absolute dominance of the kossmaticeratids Maorites andMaorites and
Grossouvrites, the abundance of which is over 80% for most of the sequence. The diversity pattern of the N Sequence
is typical for transgressive-regressive cycles, where maximum diversity is controlled by enlargement of the shelf during
peak transgression. Conversely, the diversity pattern of the NG and MG Sequences differs markedly and do not reflect
the expansion of the shelf during transgression. This unusual pattern is accompanied by dominance of the
Kossmaticeratidae concomitant with a known temperature decline of the sea water, supporting the idea that
kossmaticeratids were a stenothermal group. The Cretaceous cooling peak in Antarctica is in the Maastrichtian,
apparently coincident with the minimum kossmaticeratid diversity in Antarctica and the maximun Maastrichtian
kossmaticeratid diversity reached at lower latitudes, e.g. in Australia, suggesting the displacement of the group towards
its preferred sea-water temperature.
is typical for transgressive-regressive cycles, where maximum diversity is controlled by enlargement of the shelf during
peak transgression. Conversely, the diversity pattern of the NG and MG Sequences differs markedly and do not reflect
the expansion of the shelf during transgression. This unusual pattern is accompanied by dominance of the
Kossmaticeratidae concomitant with a known temperature decline of the sea water, supporting the idea that
kossmaticeratids were a stenothermal group. The Cretaceous cooling peak in Antarctica is in the Maastrichtian,
apparently coincident with the minimum kossmaticeratid diversity in Antarctica and the maximun Maastrichtian
kossmaticeratid diversity reached at lower latitudes, e.g. in Australia, suggesting the displacement of the group towards
its preferred sea-water temperature.
is typical for transgressive-regressive cycles, where maximum diversity is controlled by enlargement of the shelf during
peak transgression. Conversely, the diversity pattern of the NG and MG Sequences differs markedly and do not reflect
the expansion of the shelf during transgression. This unusual pattern is accompanied by dominance of the
Kossmaticeratidae concomitant with a known temperature decline of the sea water, supporting the idea that
kossmaticeratids were a stenothermal group. The Cretaceous cooling peak in Antarctica is in the Maastrichtian,
apparently coincident with the minimum kossmaticeratid diversity in Antarctica and the maximun Maastrichtian
kossmaticeratid diversity reached at lower latitudes, e.g. in Australia, suggesting the displacement of the group towards
its preferred sea-water temperature.
, the abundance of which is over 80% for most of the sequence. The diversity pattern of the N Sequence
is typical for transgressive-regressive cycles, where maximum diversity is controlled by enlargement of the shelf during
peak transgression. Conversely, the diversity pattern of the NG and MG Sequences differs markedly and do not reflect
the expansion of the shelf during transgression. This unusual pattern is accompanied by dominance of the
Kossmaticeratidae concomitant with a known temperature decline of the sea water, supporting the idea that
kossmaticeratids were a stenothermal group. The Cretaceous cooling peak in Antarctica is in the Maastrichtian,
apparently coincident with the minimum kossmaticeratid diversity in Antarctica and the maximun Maastrichtian
kossmaticeratid diversity reached at lower latitudes, e.g. in Australia, suggesting the displacement of the group towards
its preferred sea-water temperature.