越南北部Tong Vai Valley下泥盆统介形类Sinoleperditiinae(英文)

SINOLEPERDITIINAE (OSTRACODA) FROM THE LOWER DEVONIAN OF TONG VAI VALLEY,NORTH VIETNAM

文中研究的介形类化石系由越南Tong-Dzuy等于1991年和1993年采自越南北部Tong Vai Valley地区Tong Vai剖面Khao Loc组的第二段。经初步研究鉴定,计2属、5种,分别是Sinoleperditia(Sinoleperditia)cf.yulinensis Wang,1994,S.(S.)liujingensis Wang,1996,S.(S.)subbrevis Wang,1994,S.(S.)tongvaiensis sp.nov.和Qujingsiasp.。除Qujingsiasp.是瘤石介科(Beyrichiidae)的分子外,其余均为中华豆石介亚科(Sinoleperditiinae)的成员。在中华豆石介亚科4个种中,共有7枚标本同时保存有下垂"V"型肌痕(trailing chevron muscle scar)和闭壳肌痕(adductor muscle scar),其下垂"V"型肌痕高度(th)与闭壳肌痕高度(ah)之比,变化从0.675到0.71,平均比值约为0.694。Khao Loc组第二段赋含中华豆石介亚科分子的层位大致可与云南曲靖地区西屯组下―中部和广西六景地区莲花山组下部对比,时代为中―晚洛霍考夫期,并倾向于晚洛霍考夫期。介形类生态组合及相关共生生物特征,表明Khao Loc组第二段赋含介形类化石的地层可能是在潮间带环境下沉积的。由于Tong Vai Valley地区Khao Loc组第二段产有中华豆石介亚科化石,故越南北部可能为华南泥盆纪介形类生物地理区系的组成部分。最近,赵文金等(Zhao et al.,2011)通过碳同位素地层和微脊椎动物组合序列的研究,指出云南曲靖地区的志留系―泥盆系界线(SDB)在玉龙寺组顶部或西山村组(下西山村组)的底部。这一界线与我们之前根据介形类,特别是中华豆石介亚科化石建议的界线一致(王尚启等,1992;王尚启,1994;方宗杰等,1994),进而证明我们之前推测的下西山村组下部时代,亦即中华豆石介亚科的始现时间为早洛霍考夫期是正确的。

In this research study, ostracodes were examined that were originally collected by Tony-Dzuy et al. in 1991 and 1993 from the Second Member of the Khao Loc Formation at the Tong Vai section of Tong Vai Valley, North Vietnam. Two genera and five species are preliminarily recognized as follows： Sinoleperditia （Sinoleperditia） cf. yulinensis Wang, 1994, S. （S. ） subbrevis Wang, 1994, S. （S. ） liujingensis Wang, 1996, S. （S. ） tongvaien- sis sp. nov. and Qujingsia sp. They are assigned to the Sinoleperdiriinae Wang, 1994 except for the last one, which is a taxa of Beyr/chiidae M＇Coy, 1846. In these four sinoleperditiine species, seven individual specimens possess bothtrailing chevron and adductor muscle scars; their ratios of vertical height of trailing chevron muscle scar （th） to that of adductor muscle scar （ah） range from about 0. 675 to 0.71, with a mean value of about 0. 694. The Sinoleperditi- inae bearing beds in tile Second Member of Khao Loc Formation may be approximately correlated with tile lower- middle part of Xitun Formation in Qujing of Yunnan or the Lower part of I.ianhuashan Formation of Liujing in Guan- gxi and are considered to be middle to late I.oehkovian, particularly late Loehkovian in age. The Sinoleperditiinae- bearing beds in the Second Member of Khao Loc Formation might be deposited in an intertidal environment.