卷曲藻Grypania属在蓟县高于庄组中的确认及其意义

CONFIRMATION OF THE GENUS GRYPANIA (MEGASCOPIC ALGA) IN GAOYUZHUANG FORMATION (1434Ma) IN JIXIAN (TLANJIN ) AND ITS SIGNIFICANCE

本文系统描述了采自天津蓟县长城系高于庄组宏观藻类化石1属4种（包括1新种）。认为前人所建新属桑树鞍藻属（SangshuaniaDu，1986）即为美国西部上前寒武系贝尔特超群格雷松页岩中的卷曲藻属（GrypaniaWalteretal，1976）。高于庄组（1434Ma）与格雷松页岩（1400Ma）在层位上大体相当，得到古生物化石上的直接证据，具有重要的地层意义。而远隔浩瀚的太平洋东西两岸的华北古陆与劳仑古陆在中元古时产有相同的古生物化石，则蕴含着古地理古构造上的深刻意义。

Genus Grypania (Walcott, 1899) (megascopic algalfossil) was found firstly fromthe Gryson Shales, Ravalli Group, Belt Supergroup (Upper Precambrian) in Montana State,Western America. It has been classified to the animal trace fossils by American palaeontlogistWalcott C. D., in 1899, including 3 species: Helminthoidichnires? sgiralis, H. ? neihatensis,H. meekii (C. D., Walcott, 1899; p. 236, Pl. 24, figs. 1 ~7). Since then, the trace genusHelminthoidichnites was considered as a megascopic alga by Amrican palaeontologist Cloud P.E. (P. E., Cloud, 1968). In l976, Australian palaeontologist Walter M. R. et al. establishednew genus Grygania (Walcott, 1899) in the type specimen of the species Helminthoidichnites?spiralis Walcott, 1899, and considered this genus as a probalbly eukaryotic alga (M. R. Walteret al., 1976, pp. 872 ~ 878, P1. 2, figs. 4 ~ 1O). In 1986, new megascopic fossil genus Sangshuania Du, 1986 was found firstly from Gaoyuzhuang Formation, Changcheng System in Sangshuan Village, Jixian County, China by professor Du Ru-lin (Du Ru-lin et al., 1986, pp. 115~120, P1. 1, figs. 1 ~ 14). Recently, the writer found a lot of the specimens preserved Perservtly inthe same place as Du's. They exhibit evident, regular segmentations along a portion of theirlengths. There are evident letral cell-walls and tranvers cell-walls in the algal body of genus Sangshuania Du, 1986. Therefore, the genus Sangshuania Du, 1986 is of a filamentous system of alga-body. According to the morphology, size, and width of the filaments, genus SangshuaniaDu, 1986 is equivalent to Walter's genus Grypania Walter et al, 1976.Confirmation of the genus Grypania Walter et al., 1976 in Gaoyuzhuang Formation has impohant significance in the subdivision and correlation of the strata between Gaoyuzhuang Formation (1434 Ma), Changcheng System in the western seacoast of Pacific Ocean and Gryson Shales(1325 Ma), Belt Supergroup in eastem seacoast of Pacific Chean (See table 1 ). There is samekind of genus Grypania at almost same time in two different places separated by Pacific Ocean.Were North China Craton and laurentian Block very near then? Maybe they were in one suppercontinental, which should be verified in future.