新疆准噶尔盆地和塔里木盆地二叠纪孢粉组合的比较及其植物区系和地层意义

COMPARISON OF PERMIAN PALYNOFLORAS FROM THE JUNGGAR AND TARIM BASINS AND ITS BEARING ON PHYTOPROVINCIALISM AND STRATIGRAPHY

根据二十年来积累的准噶尔和塔里木盆地二叠纪孢粉组合序列资料 ,结合其他动植物化石证据 ,初步做了两地二叠纪孢粉生物地层对比 ,并讨论了植物区系性质 ,指出准噶尔盆地在晚石炭世早期已属亚安加拉区 ,塔里木盆地在早二叠世虽总体上属欧美区 ,但已混生若干安加拉—亚安加拉成分 ,中、晚二叠世基本上已属亚安加拉区。孢粉证据支持准噶尔板块在早石炭世已与哈萨克斯坦板块—西伯利亚板块对接、塔里木板块在早二叠世与准噶尔板块对接的假说。二叠纪时 ,两地处于亚热带—暖温带 (4 0°N以南 ) ,气候总体上为半干旱气候 ,但干旱程度并不严酷 ,局部地区或层位偶尔还形成薄煤层或煤线 。

Comparison of Permian palynofloras from the Junggar and Tarim Basins has resulted in a stratigraphic correlation table (Table 1) and new understanding of the phytoprovincial problem of Tarim during the Permian. The Junggar block had been part of the Subangara Area since the early Late Carboniferous (early Bashikirian). The Tarim block seemed still to belong to the Euramerican Province in the Early Permian, although in the assemblages already existed some Angara-Subangara elements in association with quite a number of relic Carboniferous spore taxa. A dramatic change of phytoprovincialism happened no later than the onset of Middle Permian when Peltaspermalean striate pollen with an aspect of Subangara dominated. The palynological evidence lends support to the assumptions that the collision of Junggar block with the Kazakhstan-Siberia blocks was during the late Hercynian time, and that of Tarim with the northern blocks (e.g. Junggar) was in the Early Permian. Both Junggar and Tarim were situated south to 40°N. and basically under the control of a warm and semiarid climate during the Permian, and Tarim was assumed to be a little drier than Junggar judging from the diversity of spore-pollen taxa, especially in the Middle-Late Permian. However, both regions were occasionally and regionally influenced by wet climate as evidenced by the rare occurrence of thin coal seams or lines.