Continuing paleomagnetic and micropaleontological dating of Eltanin ...
WIVE
49'
490S
Location of samples sites on Kerguelen Islands, Right lower: map of Kerguelen showing location of areas in two topographic maps. Right upper: southern edge of Corbet peninsula showing location of sampled sections on Mt. Chateau and Grande Cascade. Location of French base shown. Left: map of Foch Island showing location of Port Mary section. In both topographic maps contours are at 100 meter intervals.
vey). The plutonic samples have been provided by Dr. J . Nougier (University of Paris). The results have been analysed in the context of the "microcontinental hypothesis," whereby several authors have envisaged the Kerguelen-Gaussberg ridge as a continental fragment remaining after the separation of Gondwanaland. The results do not provide any data consistent with the microcontinent idea, although they do not exclude such a possibility. The collections were made with the generous permission and logistic assistance of M. P. Rolland, Administrator of the Territoire des Terres Australes et Antarctiques Françaises. This work was supported by National Science Foundation grant GV-32480. 202
Reference Nougier, J ., and J. Lameyre. 1972. The problem of the origin of the plutonic rocks of the Kerguelen Islands, Southern Indian Ocean (abstract). EQS (Transactions of the American Geophysical Union), 53(4): 547.
Continuing paleomagnetic and micropaleontological dating of Eltanin deep-sea sedimentary cores N. D. WATKINS and J. P. KENNETT Graduate School of Oceanography University of Rhode Island Sedimentation rates are being determined for all Eltanin deep-sea sedimentary cores, using a combi ANTARCTIC JOURNAL
Figure 1. Map of second order trend surface on the sedimentation rate (in cm/1000 years) for the period t = 0 to 2.5 million years, using Eltanin cores of minimum length 5 meters if confined to Brunhes age. See Watkins and Kennett (1972) for discussion of the effect of using cores of the above minimum length, and the role of extrapolation in extending the surface over a region where sediment of 0 to 2.5 million years is largely absent (see fig. 2).
Figure 2. Map of second order trend surface on the age (In millions of years) of the sediment at the base of the regional disconformity, as detected in Eltanin cores, south of Australia. From Watkins and Kennett (1972).
nation of paleomagnetic and micropaleontological methods. Regional analyses of the area south of Australia and New Zealand have been published (Watkins and Kennett, 1972) using 126 cores taken up through Cruise 39: the major discoveries are an overall, sedimentation rate pattern that is related to the configuration of the midoceanic ridge system (fig. 1), and a region of scour that is concentrated on the south Tasman Sea (fig. 2). The latter discovery reflects a substantial finite increase in average bottom water velocity sometime during the mid-Pliocene, probably because of increased Antarctic Bottom Water production (Watkins and Kennett, 1971). These discoveries have led to speculation on the sedimentary character between Australia and Antarctica during early phases of the associated continental separation, in the Lower Tertiary (Watkins and Kennett, in press). This study is currently being extended to the cores taken during Cruises 40 through 50, which are dominantly from the southern Indian Ocean. The effect of circumantarctic current on the sedimentary character (which has been readily defined by the earlier studies to the east) is present, but is not as well defined in the southern Indian Ocean. Related but independent analyses now in progress include measurement of the concentration of at-
mospherically transported volcanic dust in west to east traverses of Eltanin cores, downwind across the South Pacific from Pleistocene and Late Pliocene volcanic eruptions in the vicinity of the Balleny Islands (Huang et al., 1972), as originally detected by Kennett and Watkins (1970). This work was supported by National Science Foundation grant GV-25400.
September-October 1972
References Huang, T. C., N. D. Watkins, D. M. Shaw, and J . P. Kennett. 1972. Atmospheric volcanic dust load over the Southern Ocean, 1972. EQS (Transactions of the American Geophysical Union), 53: 423. Kennett, J . P., and N. D. Watkins. 1970. Geomagnetic polarity change, volcanic maxima, and faunal extinction in the South Pacific. Nature, 227(5261): 930-934. Watkins, N. D., and J . P. Kennett. 1971. Antarctic Bottom Water: major change in velocity during the Late Cenozoic between Australia and Antarctica. Science, 173: 813-818. Watkins, N. D., and J . P. Kennett. 1972. Regional sedimentary disconformities and Upper Cenozoic changes in bottom water velocities between Australasia and Antarctica. Antarctic Research Series, 19: 273-293. Watkins, N. D., and J . P. Kennett. In press. Response of deep-sea sediments to changes in physical oceanography resulting from separation of Australasia and Antarctica. In: Continental Drift, Sea Floor Spreading, and Plate Tectonics —Implications for the Earth Sciences (D. H. Tarling and S. K. Runcorn, eds.).
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49'
490S
Location of samples sites on Kerguelen Islands, Right lower: map of Kerguelen showing location of areas in two topographic maps. Right upper: southern edge of Corbet peninsula showing location of sampled sections on Mt. Chateau and Grande Cascade. Location of French base shown. Left: map of Foch Island showing location of Port Mary section. In both topographic maps contours are at 100 meter intervals.
vey). The plutonic samples have been provided by Dr. J . Nougier (University of Paris). The results have been analysed in the context of the "microcontinental hypothesis," whereby several authors have envisaged the Kerguelen-Gaussberg ridge as a continental fragment remaining after the separation of Gondwanaland. The results do not provide any data consistent with the microcontinent idea, although they do not exclude such a possibility. The collections were made with the generous permission and logistic assistance of M. P. Rolland, Administrator of the Territoire des Terres Australes et Antarctiques Françaises. This work was supported by National Science Foundation grant GV-32480. 202
Reference Nougier, J ., and J. Lameyre. 1972. The problem of the origin of the plutonic rocks of the Kerguelen Islands, Southern Indian Ocean (abstract). EQS (Transactions of the American Geophysical Union), 53(4): 547.
Continuing paleomagnetic and micropaleontological dating of Eltanin deep-sea sedimentary cores N. D. WATKINS and J. P. KENNETT Graduate School of Oceanography University of Rhode Island Sedimentation rates are being determined for all Eltanin deep-sea sedimentary cores, using a combi ANTARCTIC JOURNAL
Figure 1. Map of second order trend surface on the sedimentation rate (in cm/1000 years) for the period t = 0 to 2.5 million years, using Eltanin cores of minimum length 5 meters if confined to Brunhes age. See Watkins and Kennett (1972) for discussion of the effect of using cores of the above minimum length, and the role of extrapolation in extending the surface over a region where sediment of 0 to 2.5 million years is largely absent (see fig. 2).
Figure 2. Map of second order trend surface on the age (In millions of years) of the sediment at the base of the regional disconformity, as detected in Eltanin cores, south of Australia. From Watkins and Kennett (1972).
nation of paleomagnetic and micropaleontological methods. Regional analyses of the area south of Australia and New Zealand have been published (Watkins and Kennett, 1972) using 126 cores taken up through Cruise 39: the major discoveries are an overall, sedimentation rate pattern that is related to the configuration of the midoceanic ridge system (fig. 1), and a region of scour that is concentrated on the south Tasman Sea (fig. 2). The latter discovery reflects a substantial finite increase in average bottom water velocity sometime during the mid-Pliocene, probably because of increased Antarctic Bottom Water production (Watkins and Kennett, 1971). These discoveries have led to speculation on the sedimentary character between Australia and Antarctica during early phases of the associated continental separation, in the Lower Tertiary (Watkins and Kennett, in press). This study is currently being extended to the cores taken during Cruises 40 through 50, which are dominantly from the southern Indian Ocean. The effect of circumantarctic current on the sedimentary character (which has been readily defined by the earlier studies to the east) is present, but is not as well defined in the southern Indian Ocean. Related but independent analyses now in progress include measurement of the concentration of at-
mospherically transported volcanic dust in west to east traverses of Eltanin cores, downwind across the South Pacific from Pleistocene and Late Pliocene volcanic eruptions in the vicinity of the Balleny Islands (Huang et al., 1972), as originally detected by Kennett and Watkins (1970). This work was supported by National Science Foundation grant GV-25400.
September-October 1972
References Huang, T. C., N. D. Watkins, D. M. Shaw, and J . P. Kennett. 1972. Atmospheric volcanic dust load over the Southern Ocean, 1972. EQS (Transactions of the American Geophysical Union), 53: 423. Kennett, J . P., and N. D. Watkins. 1970. Geomagnetic polarity change, volcanic maxima, and faunal extinction in the South Pacific. Nature, 227(5261): 930-934. Watkins, N. D., and J . P. Kennett. 1971. Antarctic Bottom Water: major change in velocity during the Late Cenozoic between Australia and Antarctica. Science, 173: 813-818. Watkins, N. D., and J . P. Kennett. 1972. Regional sedimentary disconformities and Upper Cenozoic changes in bottom water velocities between Australasia and Antarctica. Antarctic Research Series, 19: 273-293. Watkins, N. D., and J . P. Kennett. In press. Response of deep-sea sediments to changes in physical oceanography resulting from separation of Australasia and Antarctica. In: Continental Drift, Sea Floor Spreading, and Plate Tectonics —Implications for the Earth Sciences (D. H. Tarling and S. K. Runcorn, eds.).
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