摘要
白垩纪放射虫硅质岩广泛分布于藏南雅鲁藏布蛇绿岩带两侧,形成于多种沉积-构造背景,为藏南特提斯演化研究提供了丰富信息。为确定硅质岩的时代,需要建立藏南白垩纪放射虫分带系统。作为第一步,本文重新研究了江孜地区宗卓组含白垩纪早期放射虫(吴浩若和李红生,1982)的滑塌岩块标本(80-R1),描述了放射虫化石29种,包括6个新种。有13种见于阿曼同期的放射虫动物群(Dumitrica et al.,1997),其中Loopus yangi和Stichocapsa labyrinthica限于白垩纪初贝里阿斯期。藏南和阿曼的动物群中都富含Godia Wu和Becus Wu两属,前者始现于贝里阿斯期(O'Dogherty et al.,2009)。此外,Obesacapsula polyedra是加利福尼亚贝里阿斯期放射虫动物群的重要分子。宗卓组化石组合与藏南下鲁硅岩的Pseudodictyomitra carpatica带(KR1)(Matsuoka et al.,2002)比较,仅有很少共同分子。下鲁硅岩中该带的时代被归于提塘期-瓦兰今期。然而,其所含Eucyrtidiellum pyramis以及与含Loopus primitivus的西太平洋P.carpatica带底部化石群的密切关系,指示其时代可能限于晚侏罗世提塘期。
Cretaceous radiolarian cherts are widely exposed on both sides of the Yarlung Zangbo ophiolite belt, southern Tibet, China. They formed in various tectonic--sedimentary settings and provides abundant information for understanding the evolutionary history of the Tethyan ocean in southern Tibet. In order to know ages of these cherts, it is necessary to establish a regional Cretaceous radiolarian zonation in southern Tibet. This study re-analyzed the sample（80-R1） containing an abundant earliest Cretaceous radiolarian fauna from an olistolith of the Zongzhuo Formation in Jiangzi district （Wu and Li, 1982）. A total of 29 species, including 6 new species, are described in this paper. There are 13 commonly occurring species with coeval radiolarian fauna in Oman （Dumitriea et al. , 1997）, of which Loopus yangi Dumitrica and Stichocapsa labyrinthica Dumitrica are restricted in Berriasian strata in Oman. The gen- era Godia Wu and Becus Wu are abundant in both faunas and the former appeared first in Berriasian. Besides, Obesacapsula polyedra （Steiger） is an important Berriasian taxon in California （Pessagno et al. , 2009）. It is worth noting that there are few common taxa between this radiolarian assemblage and the Pseudodictyomotra carpatica zone （KR1） of Matsuoka et al. （2002） from the Xialu chert in southern Tibet, assigned to late Tithonian -- early Valanginian. The presence of Eucyrtidiellum pyramis in KR1 and its faunal similarity with the basal part containing Loopus prirnitivus of the west Pacific P. carpatica zone （Matsuoka et al. , 2005） indicate that the age of Xialu fauna （KR1） is likely of late Tithonian.
出处
《微体古生物学报》
CSCD
北大核心
2017年第4期343-359,共17页
Acta Micropalaeontologica Sinica
基金
科技部基础性工作专项(2013FY113000)
国家自然科学基金青年基金(41402016)部分资助~~
