Radiolarian-bearing cherts are widely exposed in the volcanic-sedimentary sequences associated with the Purang ophiolitic mélange in the western segment of the Yarlung Tsangpo suture zone. Highly diverse and well preserved Lower Cretaceous (Valanginian–Hauterivian) radiolarian assemblages that correlate to the Cecrops septemporatus Zone occur in bedded cherts in the Peiersanggangmu section of the southern Purang ophiolitic mélange. Fifty-five species belonging to 38 genera, including characteristic species: Archaeodictyomitra apiarium (Rüst), Cecrops septemporatus (Parona), Hemicryptocapsa capita Tan, Pseudodictyomitra carpatica (Lozyniak), and Svinitzium pseudopuga Dumitrica, have been recognized.

Geochemistry of the cherts reveals high SiO₂ contents (average: 92.23 wt%), Al/(Al + Fe + Mn) ratios, and low La_N/Ce_N ratios. Post Archean Australian Shale (PAAS) normalized rare earth element (REE) abundance patterns exhibit moderately positive Ce anomalies (mean Ce/Ce* =1.35) with relative enrichment in light rare earth elements (LREEs). These features are indicative of deposition in an oceanic basin close to a continental margin environment. Lithological characteristics and geochemical results suggest that the paleogeographical location for these radiolarian-bearing bedded cherts closely matches northern regions of the Indian continent, where existed enhanced upwelling activity and surface mixing resulting from monsoon activities.

含放射虫的硅质岩广泛出露于雅鲁藏布江缝合带西段与 Purang 蛇绿混杂岩相关的火山-沉积层序中。与Cecrops septemporatus带相关的高度多样化且保存完好的下白垩世（Valanginian-Hauterivian）放射虫组合出现在 Purang 蛇绿混杂岩南部 Peiersangganmu 部分的层状硅质岩中。38属55种，包括特征种：Archaeodictyomitra apiarium (Rüst)、Cecrops septemporatus (Parona)、Hemicryptocapsa capita Tan、Pseudodictyomitra carpatica (Lozyniak)和Svinitzium pseudopuga杜米特里卡，已被认可。

燧石的地球化学揭示了高 SiO ₂含量（平均：92.23 wt%）、Al/(Al + Fe + Mn) 比率和低 La _N/ Ce _N比率。太古宙后澳大利亚页岩 (PAAS) 归一化稀土元素 (REE) 丰度模式表现出适度正 Ce 异常（平均 Ce/Ce* =1.35），轻稀土元素 (LREE) 相对富集。这些特征表明沉积在靠近大陆边缘环境的洋盆中。岩性特征和地球化学结果表明，这些含有放射虫的层状硅质岩的古地理位置与印度大陆北部地区非常吻合，那里存在因季风活动而增强的上升流活动和地表混合。