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Late Paleozoic Glacial Episodes in Gondwanaland Reflected in Transgressive-Regressive Depositional Sequences in Euramerica

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Late Paleozoic Glacial Episodes in Gondwanaland Reflected in Transgressive-Regressive Depositional Sequences in Euramerica Late Paleozoic glacial episodes in Gondwanaland reflected in transgressive-regressive depositional sequences in Euramerica J J VEEVERS 1 C McA POWELL 1 J^ustra^n ^esearc^ Group, School of Earth Sciences, Macquarie University, New South Wales, 2109, Australia ABSTRACT INTRODUCTION which straddled the equator so that its wide- spread shallow-marine to paralic sequences The Late Paleozoic glaciation of Gondwan- New information concerning (a) the age and contain rich faunas, including those of the short- aland comprised two short episodes, in the extent of Late Paleozoic ice centers in Gond- ranging ammonoids, fusulinid foraminifera, and Famennian (I) and Visean (II) confined to wanaland (Hambrey and Harland, 1981; Caputo conodonts (Ross and Ross, 1985a). Except Brazil and adjacent northwest Africa, and a and Crowell, 1985; Martinez Diaz, 1985) and along its Paleo-Tethyan and Paleo-Pacific ma- long episode that started in the Namurian (b) the age of depositional transgressive-regres- rine margins, the Gondwanaland sequences are (IIIA) of eastern Australia and Bolivia/ sive sequences in Euramerica (Johnson and nonmarine, and only the ubiquitous microflora Argentina, expanded to cover much of others, 1985; Ross and Ross, 1985a, 1985b; affords the means for regional correlation and a Gondwanaland in the Stephanian/Asselian Heckel, 1986; Saunders and Ramsbottom, less secure inter-regional correlation (Anderson, (IIIB), and collapsed in the early Sakmarian 1986) confirms Wanless and Shepard's (1936) 1981; Truswell, 1980). Nevertheless, the age of (IIIC). Dropstones in eastern Australia indi- hypothesis that Euramerican cyclothems were the microfloras can be linked to that of the Eur- cate that small ice centers lingered to the controlled largely by sea-level fluctuations re- american faunas by way of the rare Euramerican Kazanian. Across the belt of low latitudes lated to climatic variation during the Gondwana- taxa in the cold-water faunas of the Gondwana- north of Gondwanaland, short-ranging fossils land glaciation. Of the three episodes of the Late land margins, as, for example, by the occurrence in widespread shallow-marine and paralic Paleozoic glaciation, episode I (Famennian) was of the early Namurian ammonoid Cravenoceras deposits indicate synchronous deposition of localized to Brazil and adjacent northwest in the eastern Australian fauna of the Levipus- transgressive-regressive sequences in differ- Africa, and II (Visean) to Brazil; only episode III tula levis zone, dominated by the longer-ranging ent parts of Euramerica. These sequences (Namurian to Sakmarian) extended across brachiopods and bivalves. Correlation within correlate with glacial events in Gondwana- Gondwanaland. All three glacial episodes cor- Gondwanaland at the transition from the Car- land at three levels: (a) four major regressions relate with transgressive-regressive sea-level events boniferous to the Permian is uncertain because in Euramerica, in the Famennian (1), Visean in Euramerica, and the extensive episode III of poor age-calibration between the marine fau- (2), Namurian (3), Stephanian (4), and the correlates with cyclothemic deposition in nas and nonmarine microfloras; here we follow Tastubian transgression that preceded the Euramerica. Wanless and Shepard (1936) indi- the palynostratigraphic scheme that places the Sterlitamakian regression (S), also recorded cated the possibility of a general correlation of Carboniferous-Permian boundary between Units in Gondwanaland, correlate with glacial epi- the interval of glaciation with that of cyclo- II and III of Western Australia and Stages 2 and sodes I, II, and IIIA, mB, and mC; (b) the themic deposition, and Crowell (1978) nar- 3 of eastern Australia (Kemp and others, 1977; time-interval of cyclothemic deposition in rowed the correlation by showing that glaciation Balme, 1980), rather than at the base of Unit II Euramerica (Brigantian or latest Visean to lasted from the Visean to the lowermost or Stage 2, as advocated by Archbold (1982) Sterlitamakian) correlates with that of glacial Kazanian. Here we (1) refine this correlation by and Dickins (1984). Radiometric dates are con- episode III; and (c) the dominant period of establishing the precise start of glaciation of nected to the biostratigraphic scale after Harland the Euramerican cyclothems, as estimated episode III from eastern Australia as earliest and others (1982), in which the error of the Late from the Middle and Late Pennsylvanian Namurian, (2) show that the main regressions Paleozoic tie-points ranges from ±6 to ±11 m.y. are dominated by glacio-eustatic drawdown of deposits of the mid-continent of North Amer- The second difficulty is due to the onset of the sea level and the terminal transgression to ica, and of the thickest known Gondwana- main glaciation (episode III) being represented, glacio-eustatic rise of sea level, and (3) that the land glacigenic sediment (the earliest Permian except in a few places, by a mid-Carboniferous cyclic period of cyclothemic and glacial deposi- Lyons Group of Western Australia) is 0.4 (Namurian) stratigraphic gap or lacuna so that tion is the same and that it corresponds to the Ma, equivalent in turn to the long orbital- the onset of this episode has been overshadowed long period of orbital eccentricity in the Quater- eccentricity period of the Quaternary ice age, by the later maximum glaciation of episode IIIB. nary and Miocene. and the dominant period of fluctuation of the In the analysis that follows, we scrutinize this late Miocene Antarctic ice cap. That it has taken 50 yr to apply a rigorous test lacuna in each Gondwanan region, and point The three levels of correlations confirm of Wanless and Shepard's (1936) hypothesis is out evidence of coeval deformation and uplift, Wanless and Shepard's (1936) hypothesis due to two difficulties. The first arises from the which may have triggered the mid-Carbon- that the Late Paleozoic cyclothems are con- biostratigTaphical time-resolution of the Pennsyl- iferous glacial episode (Powell and Veevers, trolled largely by sea-level fluctuations re- vanian and Permian sequences in Gondwana- 1987). Because the lacuna is more readily inter- lated to the Gondwanaland glaciation. land being greatly inferior to that in Euramerica, pretable in Australia, we start with this region. Geological Society of America Bulletin, v. 98, p. 475-487,6 figs., 3 tables, April 1987. 475 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/98/4/475/3419664/i0016-7606-98-4-475.pdf by guest on 30 September 2021 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/98/4/475/3419664/i0016-7606-98-4-475.pdf by guest on 30 September 2021 PALEOZOIC GLACIAL EPISODES IN GONDWANALAND 477 including the Macleay area, a coeval decrease in TABLE 1. SOURCE OF INFORMATION GIVEN IN FIGURE 2 Figure 1. Late Paleozoic paleogeography the diversity of brachiopods (Roberts, 1981) and Topic Author of Gondwanaland, showing distribution of the disappearance of warm-water oolite confirm glacigenic sediment and inferred and postu- a fall in temperature. An indirect indication of TASMAN FOLD BELT lated ice in glacial episodes I-m, areas of glaciation is provided by the marine Kullatine Crowell and Frakes (1971) orogenic uplift, and carbonate sediment. Formation. Crowell and Frakes (1971) "found Sydney, Werrie, Hambrey and Harland (1981) Tamwonh, Leitch (1974) Gondwanaland reconstruction from Powell no evidence of glaciation within the depositional Macleay Basins Martinez Diaz (1985, p. 13-56) and others (1980); polar wander path and pa- environment; nonetheless, the presence of stri- McMinn (1982) leolatitudes from Schmidt and others (1986). ated stones indicates that glaciers contributed Transgression-regression Dickins (1984) McMinn (1982) Compiled from information given in Figures debris to the basin." The striated stones lie with- Roberts (1985) 2-4 with, in addition, information on glaci- in the Namurian-Westphalian Levipustula levis Veevers (1984) genic sediment in Ethiopia from Hambrey zone, a few hundred metres above an occurrence Diversity Microflora Balme (1980) and Harland (1981) and Davidson and of the short-ranging ammonoid Cravenoceras Kemp and others (1977) McGregor (1976), and in Arabia from Mc- kullatinense, which indicates the earliest Namuri- Brachiopods Roberts (1981) Clure (1980) and Braakman and others an E zone (Campbell, 1962). The Kullatine Temperature Oolite Campbell and McKellar (1969) (1982). The 400 Ma map shows also the loca- Formation is an accumulation of mass-move- Metamorphism Cas and others (1976) tion of regions 1-11 and of places marking ment deposits (Lindsay, 1966), probably depos- Shaw and others (1982) changes of latitude: Quito (QO) representing ited rapidly, so that it is likely that the first Wyborn and Owen (1983) Piutonism Powell (1983) westernmost Gondwanaland; Zomba (ZA), appearance of ice at sea level in eastern Austra- Bathurst Granite (B) S. E. Shaw (1986, persona) commun.) the centre; and Brisbane (BE), the eastern- lia was early Namurian, as confirmed by the Deformation and uplift Powell (1984) most part; all of these are given in Figure S. coeval decrease in brachiopod diversity. Galilee Basin G. D. Powis in Purcell (1984) The 255 Ma map shows also the location of Some authors (for example, Frakes, 1979), Veevers (1984) E. M. Truswell (1986, personal commun.) the transects given in Figures 2 through 4, have interpreted the glaciation as an alpine Drummond Basin Day and others (1983) including the abbreviations
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