华北板块寒武系第二统小壳化石丰富, 为小壳动物分类学、寒武纪地层划分与洲际对比以及古地理重建提供关键证据。近年来, 华北板块寒武系底部小壳化石被广泛研究, 而猴家山组作为华北板块寒武纪最早沉积地层之一, 其顶部的小壳化石组合却缺乏研究。本文首次报道了苏北地区张楼剖面寒武系猴家山组顶部海绿石灰岩中经酸蚀处理得到的小壳化石, 并对其化石组合进行了丰度统计与系统描述。该小壳化石组合共计12属12种, 其中以软舌螺类的多样性及丰度最高, 包括4属4种: Cupitheca decollatea、Paratriplicatella sp.、Neogloborilus spinatus、Triplicatella xinjia; 腕足类共3属3种: Eoobolus sp.、Schizopholis sp.、Hadrotreta sp.; 开腔骨2属2种: Chancelloria cf. eros、Archiasterella teraspina; 高肌虫2属2种: Alutella cf. datongensis、Mongolitubulus aspermachaera; 似软舌螺: Hyolithellus cf. micans。此外还有未定属种的离散海绵骨针与棘皮动物骨板等。苏北地区张楼剖面猴家山组顶部的小壳化石组合属于三叶虫Redlichia chinensis带, 通过系统研究发现其软舌螺类、腕足类、开腔骨等基本延续了辛集组的小壳化石组合面貌, 但在软体动物的组成上具有显著差异, 分析认为极有可能受到了Sinsk事件的影响。结合小壳化石和三叶虫组合特征与其他板块进行综合对比认为, 猴家山组顶部在时代上应属于寒武纪第四期中期(龙王庙期/Toyonian)。本文极大丰富了华北板块南缘寒武纪第四期的小壳化石材料, 扩展了小壳化石的发育层位, 后续将对邻区相似地层中的小壳化石发育情况继续进行系统研究, 以探究Sinsk事件对华北板块寒武纪早期生物群的影响。

The abundant small shelly fossils (SSFs) from the Cambrian Series 2 recovered from the North China Paltform (NCP) represent an important resource for SSF taxonomy, transcontinental stratigraphic correlations, and palaeogeographic reconstructions (specifically, reconstructing the relative palaeogeographic positions of the NCP). In recent years, many new species of SSFs from the Cambrian Series 2 have been reported from the NCP; however, one stratigraphic unit that has received little attention in this region is the uppermost Houjiashan Formation, one of the oldest Cambrian formations on the NCP. This study provides an extensive investigation of the SSF assemblage from the uppermost Houjiashan Formation. A total of 12 species belonging to 12 genera are identified; all are obtained through acid etching of materials from the Zhanglou section in northern Jiangsu Province. This assemblage includes four species of hyoliths (Cupitheca decollatea, Paratriplicatella sp., Neogloborilus spinatus, and Triplicatella xinjia), three species of brachiopods (Eoobolus sp., Schizopholis sp., and Hadrotreta sp.), two species of chancelloriids (Chancelloria cf. eros and Archiasterella teraspina), two species of bradoriids (Alutella cf. datongensis and Mongolitubulus aspermachaera), a hyolithelminth species (Hyolithellus cf. micans) along with unidentifiable sponge spicules, echinoderm sclerites, etc. The SSF assemblage from the uppermost Houjiashan Formation at the Zhanglou section in northern Jiangsu Province belongs to the trilobite Redlichia chinensis Zone. Consisting of hyoliths, brachiopods, and chancelloriids, this assemblage basically resembles the SSF assemblage of the Xinji Formation, but they differ in their mollusc compositions. Further analysis suggests that the difference is highly likely influenced by the Sinsk event. These new data indicate that the uppermost Houjiashan Formation belongs to the middle of the Cambrian Stage 4 (Longwangmiao Formation; Toyonian). This new discovery adds great material to and extends the biostratigraphical range of the SSFs from the Cambrian Stage 4 on the southern margin of the NCP. Palaeogeographical distribution of SSFs in similar strata of the neighbouring regions will be further studied to better understand the impact of the Sinsk event on the NCP.

国家重点研发计划(2023YFF0803601), 国家自然科学基金(42302009)和高等学校学科创新引智计划(D17013)联合资助