Abstract：The Haojiagou section， located in the southern margin of the Junggar Basin， is of great significance in studying the Triassic-Jurassic Boundary events. The lower part of the section(bed 4 to bed 44)belongs to the Haojiagou Formation that is assigned to the Upper Triassic， and the interval of bed 45 to bed 102 is the Badaowan Formation that is considered to be the Lower Jurassic. The palynological data show that the gymnosperm pollen grains dominate all the Haojiagou Formation， and fern spores have higher proportion than the gymnosperm pollen grains in the lower member of the Badaowan Formation. Taking into account that most ferns adapt to warm and humid climatic environment， we believe that it was warmer and more humid in the Early Jurassic than in the Late Triassic. Organic carbon isotope data from the Haojiagou section demonstrate that δ13C curve has an obvious negative excursion(less than -24.5‰)in the interval of bed 44 to bed 68， while the underlying and overlying strata have similar δ13C values(greater than -24.5‰). Analyses of charcoal samples show a similar negative excursion in bed 44 to bed 59. According to the results of ecological research， sedimentary organic matter has lighter carbon isotope values when the climate is warm and humid. Therefore， it is concluded that at the beginning of the Early Jurassic the climate was warmer and more humid than before and afterward.
邓胜徽， 陈芬. 2001. 中国东北地区早白垩世真蕨类植物［M］. 北京: 地质出版社. 邓胜徽， 程显胜， 齐雪峰， 等. 2000. 新疆准噶尔盆地晚三叠世—早侏罗世植物组合序列［C］. 见: 第三届全国地层会议论文集. 北京: 地质出版社， 174-178. 邓胜徽， 卢远征， 徐道一. 2005. 三叠纪末生物集群绝灭事件［J］. 中国科学（D），35(9): 799-809. 邓胜徽， 姚益民， 叶得泉，等. 2003. 中国北方侏罗系Ⅰ：地层总论［M］. 北京:石油工业出版社. 韩家懋， 王国安， 刘东生. 2002. C4植物的出现与全球环境变化［J］. 地学前缘， 9(1): 233-243. 黄克难， 詹家祯， 邹义声， 等. 2003. 新疆库车河地区三叠系和侏罗系沉积环境及古气候［J］. 古地理学报，5(2):197-208. 刘兆生. 2003. 塔里木盆地库车凹陷三叠纪和侏罗纪孢粉组合［M］. 北京: 科学出版社. 卢远征， 邓胜徽. 2005. 新疆准噶尔盆地南缘郝家沟组和八道湾组底部孢粉组合及三叠系—侏罗系界线［J］. 地质学报， 79(1):15-27. 吴兆洪， 秦仁昌. 1991. 中国蕨类植物科属志［M］. 北京:科学出版社. 余俊清， 王小燕， 李军， 等. 2001. 湖泊沉积有机碳同位素与环境变化［J］. 湖泊科学， 13(1): 72-78. 郑万钧， 傅立国，等. 1978. 中国植物志第7卷裸子植物门［M］. 北京: 科学出版社. Berner R A. 1997. Geochemistry and geophysics: The rise of plants and their effect on weathering and atmospheric CO2［J］. Science， 276: 544-546. Beerling D. 2002. CO2 and the end-Triassic mass extinction［J］. Nature， 415: 386～387. Ehleringer J R. 1993. Carbon and water relations in desert plants: An isotopic perspective［C］. In: Ehieringer J R.， Hall AE， Farquhar G D（eds）. Stable Isotopes and Plant Carbon. San Diego: Academy press， 155-172. Fabriciucs F， Friedrichsen V， Jascobshagen V. 1970. Palotemperaturen und Paloklima in Obertrias und Lias der Alpen［J］. Gel.Rundsch， 59:805-826. Fowell S J， Cornet B， Olsen P E. 1994. Geologically rapid Late Triassic extinctions: Palynological evidence from the Newark Supergroup［C］. In：Klein G D（ed）. Pangea: Paleoclimate，Tectonics and Sedimentation during Accretion， Zenith and Break-up of A Supercontinent. Geological Society of America Special Paper， 288:197-206. Guex J， Bartolini A， Atudorei V， et al. 2004. High-resolution ammonite and carbon isotope stratigraphy across the Triassic-Jurassic boundary at New York Canyon(Nevada)［J］. Earth and Planetary Science Letters，225:29-41. Hallam A. 2000. The end-Triassic extinction in relation to a superlume event［J］. Geol. Soc. Am. Abs. Prog.，37:380. Hesselbo S P， Atuart A R， Finn S， et al. 2002. Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbation: A link to initiation of massive volcanism？［J］.Geology， 30(3):251-254. Hesselbo S P，Robinson S A，Surlyk F.2004.Sea-level change and facies development across potential Triassic-Jurassic boundary horizons，SW Britain［J］.Journal of the Geological Society London，161:365-379. Kump L R， Arthur M A. 1999. Interpreting carbon-isotope excursions: Carbonates and organic matter［J］. Chemical Geology， 161:181-198. McElwain J C， Beerling D J， Woodward F Ⅰ. 1999. Fossil Plants and Global Warming at the Triassic-Jurassic Boundary［J］. Science， 285: 1386-1390. McElwain J C， Chaloner W G. 1995. Stomatal density and index of fossil plants track atmospheric carbon dioxide in the Palaeozoic［J］. Annals of Botany， 76: 389-395. Medina E， Montes G， Cueves E， et al. 1986. Profiles of CO2 concentration and δ13C values in tropical rain forests of the Upper Rio Negro basin， Venezuela［J］. J Tropipcal Ecol.， 2: 207-217. Morante R， Hallam A. 1996. Organic carbon isotopic record across the Triassic-Jurassic boundary in Austria and its bearing on the cause of the mass extinction［J］. Geology， 24(5):391-394. Olsen P E. 1999. Giant lava flows， mass extinction， and mantle plumes［J］. Science， 284: 604-605. Olsen P E, Kent D V, Sues H D, et al.2002. Ascent of dinosaurs linked to an Iridium anomaly at the Triassic—Jurassic boundary［J］. Science, 296(5571):1305-1307. Orbell G.1973.Palynology of the British Rhaeto-Liassic［J］.Bulletin of the geological Survey of Great Britain，No.44. Palfy J， Attila D， Janos H， et al. 2001. Carbon isotope anomaly and other geochemical changes at the Triassic-Jurassic boundary from a marine section in Hungary［J］. Geology， 29(11):1047-1050. Poole Ⅰ， Weyes J D， Lawson T， et al. 1996. Variation in stomatal density and index: Implications for palaeoclimatic reconstructions［J］. Plant Cell Environment， 19: 705-712. Retallack G J. 2001. A 300-million-year record of atmospheric carbon dioxide from fossil plant cuticles［J］. Nature， 411: 287-290. Retallack G J. 2002. Triassic-Jurassic atmospheric CO2 spike［J］. Nature， 415: 387-388. Tanner L H， Hubert J E， Coffey B P， et al. 2001. Stability of atmospheric CO2 levels across the Triassic/Jurassic boundary［J］. Nature， 411：675-677. van der Merwen J， Medina E. 1989. Photosynthesis and 13C/12C ratios in Amazonian rain forests［J］. Geochim.Cosmochim.Acta，53: 1091-1094. Ward P D， Haggard J W， Carter E S， et al. 2001. Sudden productivity collapse associated with the Triassic-Jurassic boundary mass extinction［J］. Science， 292: 1148-1151. Woodward F Ⅰ. 1987. Stomatal numbers are sensitive to increases in CO2 from preindustrial levels［J］. Nature， 327: 617-618.
