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Palynostratigraphy of the Mackellar Formation (Beacon Supergroup), East Antarctica THOMAS N

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Palynostratigraphy of the Mackellar Formation (Beacon Supergroup), East Antarctica THOMAS N Palynostratigraphy of the Mackellar Formation (Beacon Supergroup), East Antarctica THOMAS N. TAYLOR, EDITH L. TAYLOR, and TIM HORNER, Byrd Polar Research Center, Ohio State University, Columbus, Ohio 43210 KHAN R. MASOOD, Department of Botany, University of Punjab, Lahore, Pakistan he Mackellar Formation belongs to the Beacon Super believed to represent Upper Carboniferous(?)/Lower Permian TGroup (figure), a thick sequence of Carboniferous(?)/Per- rocks (Kyle and Schopf 1982). mian/Triassic clastics that constitute a component of an out- Samples used in this study were collected from three crop belt that extends for more than 1,000 kilometers (km) measured sections in the Beardmore Glacier area (Homer along the paleo-Pacific margin of East Antarctica. The domi- and Krissek 1991) and are representative Mackellar sediments nant lithologies in the Mackellar Formation include sand- in this region. Samples that yielded the highest total organic stone, siltstone, and shales that are litho stratigraphically carbon (TOC) together with low vitrinite reflectance values were selected for palynomorph preparation. Because of the high degree of thermal alteration in many of the Beacon sedi- ments, a relationship between the extent of alteration and Prebble Formation proximity to the intrusives was developed to increase the potential recoverability of palynomorphs. Samples were pre- pared according to techniques detailed in Masood et al. (in Falla Formation preparation) with the use of gravity settling being the most C.) critical aspect of the preparation procedure (Farabee, Taylor, C-, and Taylor 1989). Fremouw Formation Major palynomorph taxa recovered Buckley Formation from the Mackellar Formation MONOSACCATES •1 Fairchild Formation Plicatipollenites 0 Parasaccites I C.) Cannanoropollis K Potonieisporites Mackellar Formation Caheniasaccites rA Primuspollenites Cl, BISACCATES Lueckisporites C.) Pagoda Formation Chordasporites Scheuringipollenites Alisporites Sulcatisporites Cedripites TRILETES Granulatisporites Retusotriletes c. Verrucosisporites Planisporites Microbaculispora Foveosporites C I- Alexandra Formation 0 I) MONOSULCATES Cycadopites Ginkgocycadophytus MONOLETES Latosporites Stratigraphic section of the Victoria Group and other units in the PSEUDOSACCATES Beardmore Glacier region, Antarctica. Uneven lines indicate Playfordiaspora unconformities. (After Homer and Krissek 1991.) ANTARCTIC JOURNAL - REVIEW 1993 32 The table indicates the various palynomorph taxa tion and is based on grains recovered from four samples. As described from the Mackellar Formation. Monosaccate grains such, it does not represent a detailed palynostratigraphic are the most common element with azonate triletes and non- analysis of the Mackellar Formation but rather provides a taeniate bisaccates also represented in high percentages. In rough approximation of Mackellar time in East Antarctica. the lower portion of the Mackellar, approximately 80 percent The ability to extract palynomorphs from some sediments in of the grains are monosaccates. At this level, bisaccate grains the formation, even in areas where the rocks have undergone constitute approximately 1 percent of the palynomorphs with extensive thermal alteration, underscores the fact that paly- trilete and monolete forms representing approximately 5 per- nostratigraphy represents a viable source of data that can be cent of the assemblage. There is a shift moving from the used to expand the biostratigraphic correlation of Antarctica lower Mackellar to the lower middle Mackellar where a num- with other continents. ber of the monosaccates appear to drop out with those taxa This study was supported in part by funds from the remaining increasing in frequency. Toward the top of the National Science Foundation grant OPP 91-118314. unit, there is a slight increase in the frequency of bisaccates, with monocolpates and monoletes absent at this level. Fun- References gal spores and acritarchs increase in the upper portions of the section. Farabee, M.J., T.N. Taylor and E.L. Taylor. 1989. Pollen and spore The large number of monosaccates, together with the assemblages from the Falla Formation (Upper Triassic), Central reduced frequency of bisaccate grain types, suggests that the Transantarctic Mountains, Antarctica. Review of Palaeobotany and Palynology, 61, 101-138. Mackellar Formation is roughly comparable to the Parasac- Homer, T.C., and L.A. Krissek. 1991. Sedimentology, thermal alter- cites Zone established in southern Victoria Land by Kyle ation and organic carbon content as factors in paleoenvironmen- (1977). The exact age of the Parasaccites Zone is not clearly tal interpretation of fine-grained Permian clastics from the Beard- established although its stratigraphic placement is believed to more Glacier region, Antarctica. In D. Elliot (Ed.), Contributions to be somewhere near the Carboniferous/ Permian boundary. antarctic research II. (Antarctic Research Series, Vol. 53.) Washing- Our analysis suggests that the Mackellar is equivalent to ton, D.C.: American Geophysical Union. Kyle, R.A. 1977. Palynostratigraphy of the Victoria Group of South Vic- the Roaring Formation in the Nilsen Plateau and Discovery toria Land, Antarctica. New Zealand Journal of Geology and Geo- Ridge Formation in the Ohio Range. Kyle (1977) suggests the physics, 20, 1142-1150. Parasaccites Zone is adjacent to the upper stage 2 of eastern Kyle, R.A., and J.M. Schopf. 1982. Permian and Triassic palynostratig- Australia and the Microbaculispora Assemblage Zone of the raphy of the Victoria Group, Transantarctic Mountains. In C. Perth Basin, Western Australia. The large number of radially Craddock (Ed.), Antarctic geoscience. Madison: University of Wis- consin Press. symmetrical monosaccate grain types confirms the Mackellar Masood, K.R., T.N. Taylor, T. Homer, and E.L. Taylor. In preparation. assemblage as being close to stage 2 in eastern Australia. This Palynology of the Mackellar Formation (Beacon Supergroup) of is the first report of palynomorphs from the Mackellar Forma- East Antarctica. Review of Palaeobotany and Palynology. A brief review of Mesozoic terrestrial vertebrates from the Transantarctic Mountains including evidence of a scavenging theropod WILLIAM R. HAMMER and WILLIAM J. HICKERSON, Department of Geology, Augustana College, Rock Island, Illinois 61201 ince the first discovery of a Triassic temnospondyl at Pedaeosaurus parvus, and Rhigosaurus glacials, but includes SGraphite Peak in 1967 (Barrett, Baillie, and Colbert 1968), the prolacertid Prolacerta broomi, the procolophonid Pro- faunas of three different ages have been collected during colophon trigoniceps, the temnospondyls Austrobrachyops expeditions to the Central Transantarctic Mountains in jenseni, Cryobatrachus kitchingi and an indeterminant rhyti- search of Mesozoic terrestrial vertebrates. The oldest of these dosteid, and a single specimen of a thecodont reptile (Ham- faunas is earliest Triassic in age and occurs in the lower part mer and Cosgriff 1981; Colbert 1982). All taxa from the lower of the Fremouw Formation at numerous localities near the Fremouw appear to be equivalent in age with the Lystrosaurus Shackleton and Beardmore glaciers. This diverse assemblage Zone of South Africa. consists mainly of the therapsids Lystrosaurus murrayi, A second fauna from the upper Fremouw Formation is Lystrosaurus curvatus, Lystrosaurus mcCaigi, Lystrosaurus sp., known from only two localities along the Gordon Valley near Myosaurus gracilis, Thrinaxodon liorhinus, Eriolacerta parva, the Beardmore Glacier. This fauna shares a few taxa with the ANTARCTIC JOURNAL - REVIEW 1993 33.
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