Silicoflagellate Mesocena pappil identified in RISP site J ...
Silicoflagellate Mesocena pappil identified in RISP site J-9 core sediments HsIN
Yi LING and
RICHARD J . WHITE
Department of Geology Northern Illinois University De Kalb, Illinois 60115
Specimens of a silicoflagellate species, Mesocena pappii, have been recovered from Ross Ice Shelf Project (RIsP) site J-9 core sediments obtained during the 1977-78 and 1978-79 field seasons (Webb et al., 1979; Webb, 1979). This recovery represents the southernmost occurrence of this species recorded to date. M. pappii was originally described by Bachmann (1962) from the Eocene Kreyenhagen shale of Los Banos, California. It is distinguished from all other known related species of genus Mesocena by possessing two distally divergent radial spines at each of generally three but rarely four apices of the triangular basal body ring. Subsequently, Bachmann (1970) reported this species from the Oligocene samples of Egerien, Austria. The species was next reported by Ling (1973), who encountered specimens from Middle Miocene sediments of Deep Sea Drilling Project (D5DP) site 186 from the high-latitude North Pacific near the Aleutian Trench. Later, Ciesielski (1975) observed its occurrence from submarine deposits of Early Miocene of site 266 and Middle Miocene of site 272 in the Pacific Ocean sector of the Antarctic region, both collected during DSDP leg 28. Ling (1977) also recorded this species from reworked Miocene sediments of site 179 of leg 18. All these later occurrences of Early to Middle Miocene age from either the northern or southern high latitudes (see figure) are younger than that of Bachmann's original record. It is useful to note that the senior author's analysis of a suite of representative samples from the Eocene Kreyenhagen shale from Laguna Seca Hills of Merced Counts', California (north of the Los Banos area) failed to recover specimens of M. pappii. In addition, Bukry (1976) reported this species from hole 328B (a sample 3-1, 109-110 centimeters) and assigned the entire cores 3 and 4 to the Upper Oligocene Naviculopsis biapiculata zone. In contrast, Combos (1976) assigned sections 1 and 2 of core 3 to the Early Miocene Bogorovia veniamini zone (diatom). An independent examination of silico flagellates from the same holes by Busen and Wise (1976) supported Bukry's age determination but failed to produce evidence of M. pappii. Co-occurring with M. pappii in the 1977-78 and 1978-79 field seasons' J-9 core sediments were Distephanus speculum, D. quinquangellus, Cannopilus sphaericus, C. jouseae, and an ebridian species, Pseudammodochium sp. cf. P. dictyoides. An age assignment of Miocene for the
cored sediments agrees well with the determination of diatoms and pollen (Brady and Martin, 1979), and benthic foraminifera (Webb et al., 1979). The recovery
126
Reported occurrences of Mesocena pappil (solid circles) and the position of RISP J-9 site (solid square).
of these taxa (like that of M. pappii) constitutes their southernmost known occurrence. The RISP operation has been carried out with the financial support of National Science Foundation ( NSF). This work has been supported in part by NSF grants OPP 73-05834 to A. Lincoln Washburn, University of Washington (HYL) and opp 76-20657 to Peter N. Webb (RJw). The authors acknowledge Peter N. Webb's role in providing the samples during the initial phase of the study, guidance throughout the coring operation during the 1978-79 austral summer field season (RJw), and undertaking a critical review of this paper.
References
Bachmann, A. 1962. Eine Mesocena-Art (Silicoflagellidae) aus dem Kalifornischen Eozän. Verhandlungen der Geologischen Bundesanstait, Wien (Vienna), 2: 378-82. Bachmann, A. 1970. Silicoflagellaten aus dem Oberösterreichischen Egerien (Oberoligozän). Verhandlungen der Geologischen Bundesanstait, Wien (Vienna), 2: 275-305. Brady, H. T., and H. Martin. 1979. Ross Sea region in the Middle Miocene: A glimpse into the past. Science, 203: 43738.
Bukry, D. 1976. Cenozoic silicoflagellate and coccolith stratigraphy, South Atlantic Ocean, Deep Sea Drilling Project, Leg 36. In C. D. Hollister, C. Craddock, et al., initial Reports of the Deep Sea Drilling Project, 25: 885-917. Washington, D.C.: U.S. Government Printing Office. Busen, K. E., and S. W. Wise, Jr. 1976. Silicoflagellate stratigraphy, Deep Sea Drilling Project, Leg 36. In P. F. Barker, I. W. D. Dalziel, et al., Initial Reports of the Deep Sea Drilling Project, 26: 697-743. Washington, D.C.: U.S. Government Printing Office. Ciesielski, P. F. 1975. Biostratigraphy and paleoecology of Neogene and Oligocene silicoflagellates from cores recovered during Antarctic Leg 28, Deep Sea Drilling Project. In D.
E. Hayes, L. A. Frakes, et al., initial Reports of the Deep Sea
Drilling Project, 28: 625-91. Washington, D.C.: U.S. Government Printing Office. Gombos, A. M. 1976. Paleogene and Neogene diatoms from the Falkland Plateau and Malvinas Outer Basin: Leg 36, Deep Sea Drilling Project. In P. F. Barker, I. W. D. Dalziel,
et al., Initial Reports of the Deep Sea Drilling Project, 36: 575687. Washington, D.C.: U.S. Government Printing Office, Ling, H. Y. 1973. Silicoflagellates and ebridians from Leg 19, In J . S. Creager, D.W. Scholl, et al., Initial Reports of the Deep
Sea Drilling Project, 19: 751-75. Washington, D.C.: U.S. Government Printing Office. Ling, H. Y. 1977. Late Cenozoic silicoflagellates and ebridians from the eastern North Pacific region. In Proceedings of the First International Congress on Pacific Neogene Stratigraphy, Tokyo, 1976, ed. T. Saito and Ujiié, pp. 205-233.
Morphological comparison of Coscinodiscus lentiginosus Janisch and Coscinodiscus
obovatus Castracane DAVID R. DEFELICE Mobil Oil Corporation 9 Greenway Plaza, Suite 2700 Houston, Texas 77046
Morphological comparison of the diatom species CosJanisch and Coscinodiscu.s obovatus Castracane reveals that the two forms may actually be conspecific. The most common centric diatom species in
cinodiscus lentiginosus
Webb, P. N. 1979. Sediment coring at RISP J-9 (1978-79). Antarctic Journal of the United States (this issue). Webb, P. N., T. E. Ronan, Jr., J . H. Lipps, and T. E. Delaca. 1979. Miocene glaciomarine sediments from beneath the southern Ross Ice Shelf, Antarctica. Science, vol. 203, pp. 435-37.
the Southern Ocean today, C. lentiginosus is reported as first occuring in the mid-Pliocene (McCollum, 1975; Gombos, 1976), along with C. obovatus. C. obovatus appears to have been restricted to the Pliocene. C. lentiginosus is quite variable both in size (from 40 to 120 micrometers) and in aereolation pattern (from essentially radial to essentially oncentric). Most specimens display an irregular combination of the two extreme types (figures 2, 6, 7). C. obovatus displays an aereolation type identical to that found in many specimens of C. lentiginosus (compare figures 1, 3, 4, and 5 with figures
2 and 6). Both species are similar in size, spacing, and arrangement of aereolae, and both have a single prominent apiculus (figures 1, 2, 5, 8) that Fenner, Schrader, and Wienigh (1976) state is characteristic of C. lentiginosus. It appears that the two species differ only in outline. Length/width ratios in C. obovatus range from 2 to a little over 1 (figures 1, 4). Ratios approaching 1 make
differentiation between the two in Pliocene samples arbitrary.
^w%a*
Figure 1. Coscinodiscus obovatus Castracane, 1176-76, 178-180 cm, 60g.
"110 . Figure 2. Coscinodiscus lentiginosus Janisch, 1176-81, 0-1 cm, 60.
127
Yi LING and
RICHARD J . WHITE
Department of Geology Northern Illinois University De Kalb, Illinois 60115
Specimens of a silicoflagellate species, Mesocena pappii, have been recovered from Ross Ice Shelf Project (RIsP) site J-9 core sediments obtained during the 1977-78 and 1978-79 field seasons (Webb et al., 1979; Webb, 1979). This recovery represents the southernmost occurrence of this species recorded to date. M. pappii was originally described by Bachmann (1962) from the Eocene Kreyenhagen shale of Los Banos, California. It is distinguished from all other known related species of genus Mesocena by possessing two distally divergent radial spines at each of generally three but rarely four apices of the triangular basal body ring. Subsequently, Bachmann (1970) reported this species from the Oligocene samples of Egerien, Austria. The species was next reported by Ling (1973), who encountered specimens from Middle Miocene sediments of Deep Sea Drilling Project (D5DP) site 186 from the high-latitude North Pacific near the Aleutian Trench. Later, Ciesielski (1975) observed its occurrence from submarine deposits of Early Miocene of site 266 and Middle Miocene of site 272 in the Pacific Ocean sector of the Antarctic region, both collected during DSDP leg 28. Ling (1977) also recorded this species from reworked Miocene sediments of site 179 of leg 18. All these later occurrences of Early to Middle Miocene age from either the northern or southern high latitudes (see figure) are younger than that of Bachmann's original record. It is useful to note that the senior author's analysis of a suite of representative samples from the Eocene Kreyenhagen shale from Laguna Seca Hills of Merced Counts', California (north of the Los Banos area) failed to recover specimens of M. pappii. In addition, Bukry (1976) reported this species from hole 328B (a sample 3-1, 109-110 centimeters) and assigned the entire cores 3 and 4 to the Upper Oligocene Naviculopsis biapiculata zone. In contrast, Combos (1976) assigned sections 1 and 2 of core 3 to the Early Miocene Bogorovia veniamini zone (diatom). An independent examination of silico flagellates from the same holes by Busen and Wise (1976) supported Bukry's age determination but failed to produce evidence of M. pappii. Co-occurring with M. pappii in the 1977-78 and 1978-79 field seasons' J-9 core sediments were Distephanus speculum, D. quinquangellus, Cannopilus sphaericus, C. jouseae, and an ebridian species, Pseudammodochium sp. cf. P. dictyoides. An age assignment of Miocene for the
cored sediments agrees well with the determination of diatoms and pollen (Brady and Martin, 1979), and benthic foraminifera (Webb et al., 1979). The recovery
126
Reported occurrences of Mesocena pappil (solid circles) and the position of RISP J-9 site (solid square).
of these taxa (like that of M. pappii) constitutes their southernmost known occurrence. The RISP operation has been carried out with the financial support of National Science Foundation ( NSF). This work has been supported in part by NSF grants OPP 73-05834 to A. Lincoln Washburn, University of Washington (HYL) and opp 76-20657 to Peter N. Webb (RJw). The authors acknowledge Peter N. Webb's role in providing the samples during the initial phase of the study, guidance throughout the coring operation during the 1978-79 austral summer field season (RJw), and undertaking a critical review of this paper.
References
Bachmann, A. 1962. Eine Mesocena-Art (Silicoflagellidae) aus dem Kalifornischen Eozän. Verhandlungen der Geologischen Bundesanstait, Wien (Vienna), 2: 378-82. Bachmann, A. 1970. Silicoflagellaten aus dem Oberösterreichischen Egerien (Oberoligozän). Verhandlungen der Geologischen Bundesanstait, Wien (Vienna), 2: 275-305. Brady, H. T., and H. Martin. 1979. Ross Sea region in the Middle Miocene: A glimpse into the past. Science, 203: 43738.
Bukry, D. 1976. Cenozoic silicoflagellate and coccolith stratigraphy, South Atlantic Ocean, Deep Sea Drilling Project, Leg 36. In C. D. Hollister, C. Craddock, et al., initial Reports of the Deep Sea Drilling Project, 25: 885-917. Washington, D.C.: U.S. Government Printing Office. Busen, K. E., and S. W. Wise, Jr. 1976. Silicoflagellate stratigraphy, Deep Sea Drilling Project, Leg 36. In P. F. Barker, I. W. D. Dalziel, et al., Initial Reports of the Deep Sea Drilling Project, 26: 697-743. Washington, D.C.: U.S. Government Printing Office. Ciesielski, P. F. 1975. Biostratigraphy and paleoecology of Neogene and Oligocene silicoflagellates from cores recovered during Antarctic Leg 28, Deep Sea Drilling Project. In D.
E. Hayes, L. A. Frakes, et al., initial Reports of the Deep Sea
Drilling Project, 28: 625-91. Washington, D.C.: U.S. Government Printing Office. Gombos, A. M. 1976. Paleogene and Neogene diatoms from the Falkland Plateau and Malvinas Outer Basin: Leg 36, Deep Sea Drilling Project. In P. F. Barker, I. W. D. Dalziel,
et al., Initial Reports of the Deep Sea Drilling Project, 36: 575687. Washington, D.C.: U.S. Government Printing Office, Ling, H. Y. 1973. Silicoflagellates and ebridians from Leg 19, In J . S. Creager, D.W. Scholl, et al., Initial Reports of the Deep
Sea Drilling Project, 19: 751-75. Washington, D.C.: U.S. Government Printing Office. Ling, H. Y. 1977. Late Cenozoic silicoflagellates and ebridians from the eastern North Pacific region. In Proceedings of the First International Congress on Pacific Neogene Stratigraphy, Tokyo, 1976, ed. T. Saito and Ujiié, pp. 205-233.
Morphological comparison of Coscinodiscus lentiginosus Janisch and Coscinodiscus
obovatus Castracane DAVID R. DEFELICE Mobil Oil Corporation 9 Greenway Plaza, Suite 2700 Houston, Texas 77046
Morphological comparison of the diatom species CosJanisch and Coscinodiscu.s obovatus Castracane reveals that the two forms may actually be conspecific. The most common centric diatom species in
cinodiscus lentiginosus
Webb, P. N. 1979. Sediment coring at RISP J-9 (1978-79). Antarctic Journal of the United States (this issue). Webb, P. N., T. E. Ronan, Jr., J . H. Lipps, and T. E. Delaca. 1979. Miocene glaciomarine sediments from beneath the southern Ross Ice Shelf, Antarctica. Science, vol. 203, pp. 435-37.
the Southern Ocean today, C. lentiginosus is reported as first occuring in the mid-Pliocene (McCollum, 1975; Gombos, 1976), along with C. obovatus. C. obovatus appears to have been restricted to the Pliocene. C. lentiginosus is quite variable both in size (from 40 to 120 micrometers) and in aereolation pattern (from essentially radial to essentially oncentric). Most specimens display an irregular combination of the two extreme types (figures 2, 6, 7). C. obovatus displays an aereolation type identical to that found in many specimens of C. lentiginosus (compare figures 1, 3, 4, and 5 with figures
2 and 6). Both species are similar in size, spacing, and arrangement of aereolae, and both have a single prominent apiculus (figures 1, 2, 5, 8) that Fenner, Schrader, and Wienigh (1976) state is characteristic of C. lentiginosus. It appears that the two species differ only in outline. Length/width ratios in C. obovatus range from 2 to a little over 1 (figures 1, 4). Ratios approaching 1 make
differentiation between the two in Pliocene samples arbitrary.
^w%a*
Figure 1. Coscinodiscus obovatus Castracane, 1176-76, 178-180 cm, 60g.
"110 . Figure 2. Coscinodiscus lentiginosus Janisch, 1176-81, 0-1 cm, 60.
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