Late Paleozoic glaciation: Part VI, Asia: Discussion and reply

Discussion

MARTIN SCHWARZBACH Ceologisches Institut der Universität Köln, Zülpicber Strasse 49, 5 Köln, West Germany

In their comprehensive and very useful review of the Gondwana Schwarzbach 1974). Both occurrences have yet to be studied in glaciations in Asia, Frakes and others (1975) emphasize the ab- more detail, but until then they have to be considered as possible sence of glacial deposits of late Paleozoic age in the Northern indicators of glacial sediment; thus Arabia may have to be con- Hemisphere except those of India and (possibly) Siberia. That sidered as a further part of glacially influenced Gondwana. needs a little correction. Hudson (1958) mentioned tillite between sandy limestone with Metalegoceras in the southwestern Oman, MANUSCRIPT RECEIVED BY THE SOCIETY MAY 19, 1975 Arabia, and Helal (1964) described tillite from Saudi Arabia (see MANUSCRIPT ACCEPTED OCTOBER 6, 1975 Reply

L. A. FRAKES Department of Earth Sciences, Monash University, Clayton, Victoria 3168, Australia E. M. KEMP Bureau of Mineral Resources, Geology and Geophysics, Canberra, A.C.T. 2601, Australia J. C. CROWELL Department of Geological Sciences, University of California, Santa Barbara, Santa Barbara, California 93106

Professor Schwarzbach's comments reopen an unresolved ques- (1958). However, because glacial deposits appear to be lacking in tion that may become less murky as a result of discussion. We other low paleolatitude sites of the late Paleozoic, it seems more (Frakes and others, 1975) did not discuss the Middle East "gla- likely that the Middle East glacial material would have resulted cials" because their age is uncertain and because sufficient unpub- from glaciation during early Paleozoic time, but only further study lished work has been cited to suggest that they may have been and publication of detailed stratigraphic analyses can resolve this deposited during Ordovician time and not late Paleozoic time. The uncertainty. following three excerpts illustrate the "state of the art" of dating diamictite and associated strata in the Middle East and neighboring COMBINED REFERENCES CITED parts of Ethiopia. 1. "The Wajid Sandstone where it is exposed in the Tuwaig Beyth, M., 1972, Paleozoic-Mesozoic sedimentary basin of Mekele outlier, Mountains in Saudi Arabia contains sediment of glacial origin. northern Ethiopia: Am. Assoc. Petroleum Geologists Bull., v. 56, p. These rocks were previously regarded as Permo-Carboniferous on 2426-2439. 1973, Correlation of Paleozoic-Mesozoic sediments in northern the basis of pollens found in the sandstone 240 km to the north; Yemen and Tigre, northern Ethiopia: Am. Assoc. Petroleum but west of the Tuwaig Mountains the base of the sandstone has Geologists Bull., v. 57, p. 2440-2446. been dated by palynology as Cambro-Ordovician (G. Brown, per- Brown, G. F., 1970, Eastern margin of the Red Sea and the coastal struc- sonal communication)." (Dow and others, 1971, p. 58). tures in Saudi Arabia: Royal Soc. London Philos. Trans., ser. A, v. 2. "Formerly this southern segment, called the Wajid Sandstone, 267, p. 75-87. was undated except that it was known to be pre-middle Permian, Crowell, J. C., and Frakes, L. A., 1970, Phanerozoic glaciation and the but recent palynologic evidence in well cores examined by Dr. causes of ice ages: Am. Jour. Sci., v. 268, p. 193-224. Hemel has proven a Cambrian and Ordovician age (L. Dubay, Dow, D. B., Beyth, M., and Hailu, T., 1971, Palaeozoic glacial rocks re- 1968, written communication)." (Brown, 1970, p. 80). cently discovered in northern Ethiopia: Geol. Mag., v. 108, p. 53—60. Frakes, L. A., Kemp, E. M., and Crowell, J. C., 1975, Late Paleozoic 3. Regarding the northern Ethiopian Enticho Sandstone and glaciation: Part VI, Asia: Geol. Soc. America Bull., v. 86, p. 454-464. Edaga Arbi "glacial" deposits, correlated by Beyth (1973) with the Helal, A. H., 1963, Jungpalaozoische Glazialspuren auf dem Arabischen Wajid and the overlying Kohlan Series of northern Yemen, Beyth Schild: Eiszeitalter u. Gegenwalt, b. 14, p. 121-123. (1972) writes ". . . palynologic analysis by Horowitz (Tel Aviv 1964, On the occurrence and stratigraphic position of Permo-Car- Univ.) has shown the presence of forms in the Edaga Arbi glacials boniferous tillites in Saudi Arabia: Geol. Rundschau, b. 54, p. identified as not older than Devonian. According to this determina- 193-207. tion, the age of glaciation could be Permo-Carboniferous." (p. Hudson, R.G.S., 1958, Discussion, in King, L. C., Basic palaeogeography of 2435). Gondwanaland during the late Palaeozoic and Mesozoic era: Geol. A last point concerns the possible glacial origin of the Arabian Soc. London Quart. Jour., v. 114, p. 70-71. Schmidt, D. L., and Hadley, D. G., 1973, Nonglacial origin for conglomer- strata described by Helal (1963, 1964). Schmidt and Hadley (1973) ate beds in the Wajid Sandstone of Saudi Arabia: Third Internat. interpreted the Wajid conglomerate as fluvial in origin and with Gondwana Symposium, Canberra, Book of Abs., p. 49. "none of the features common to a glacial environment." Schwarzbach, M., 1974, Das Klima der Vorzeit, 3rd ed.: Stuttgart, F. Enke, If Mjddle East diamictite does indeed reflect late Paleozoic glaci- 380 p. ation, this necessarily would have taken place in paleolatitudes of less than 40° (Crowell and Frakes, 1970, Figs. 2, 3, 4). Glaciation would also have extended to near sea level, as suggested by the MANUSCRIPT RECEIVED BY THE SOCIETY MAY 19, 1975 apparently unconfirmed reports from Oman referred to by Hudson MANUSCRIPT ACCEPTED OCTOBER 6, 1975

Geological Society of America Bulletin, v. 87, p. 640, April 1976, Doc. no. 60417. 640 Printed in U.S.A.

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