贵州瓮安陡山沱期球粒状磷块岩的生物成磷作用探讨*

高川黔; 杨瑞东; 高军波; 彭柔; 李晓伟; 陈军; 陈吉艳

doi:10.7605/gdlxb.2025.041

古地理学报 ›› 2025, Vol. 27 ›› Issue (2) : 395 -410. DOI: 10.7605/gdlxb.2025.041

沉积矿产资源专题

贵州瓮安陡山沱期球粒状磷块岩的生物成磷作用探讨^*

高川黔 ¹^,² ,
杨瑞东 ¹^,² ,
高军波 ¹^,² ,
彭柔 ¹^,² ,
李晓伟 ¹^,² ,
陈军 ¹^,² ,
陈吉艳 ¹^,²

作者信息 +

Study on biogenic phosphogenesis of spheroidal phosphorite from the Doushantuo Formation in Weng’an, Guizhou Province

Chuanqian GAO ¹^,² ,
Ruidong YANG ¹^,² ,
Junbo GAO ¹^,² ,
Rou PENG ¹^,² ,
Xiaowei LI ¹^,² ,
Jun CHEN ¹^,² ,
Jiyan CHEN ¹^,²

Author information +

文章历史 +

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摘要

贵州瓮安陡山沱组海相沉积型磷块岩矿床是新元古代末期成磷事件的典型代表之一,在磷矿层中保存大量的三维立体化石,包括藻类、疑源类、动物胚胎以及休眠卵等化石类型,显示出生物在磷富集成矿中的重要作用。以贵州瓮安穿岩洞陡山沱组上磷矿层底部的球粒状磷块岩为研究对象,通过对未经化学方法处理的球粒实体进行体视显微镜和电子显微镜观察膜壳和内部结构; 对样品薄片进行光学显微镜和电子显微镜观察其显微结构特征。同时利用电感耦合等离子体发射光谱(ICP-OES)、电感耦合等离子体质谱(ICP-MS)以及X射线荧光光谱仪(XRF), 测定球粒化石颗粒中主量与微量元素含量。研究表明,这些球粒状磷块岩主要由多细胞藻类、Megasphaera球状化石以及其他磷质微生物化石体组成,化石体的主要组成矿物为氟磷灰石。进一步探讨了微生物与成磷之间的关系,认为陡山沱晚期微生物的繁盛对磷沉淀富集成矿起着重要的作用。微生物不仅能吸附磷质进入细胞质、细胞核以及细胞壁中,死亡后磷酸盐化,形成磷块岩; 还可以通过改变沉积水体环境,促进海水中磷酸盐的化学沉积。

Abstract

The marine sedimentary phosphate deposit of the Doushantuo Formation in Weng’an,Guizhou Province,is a typical representative of Late Neoproterozoic phosphate formation. This deposit preserves a diverse array of three-dimensional fossils,including algae,hypogenites,animal embryos,and dormant eggs,highlighting the crucial role of biological processes in phosphate enrichment and mineralization. This study focuses on the spheroidal phosphates found at the base of the upper phosphate layer of the Doushantuo Formation in Weng’an,Guizhou. The membrane shell and internal structure of untreated spheroidal solids were examined using stereomicroscopy and electron microscopy. The microstructures of thin sections were further analyzed through optical and electron microscopy. Additionally,the main and trace elements in the pelletal phosphorite were determined using Inductively Coupled Plasma Emission Spectroscopy(ICP-OES),Inductively Coupled Plasma Mass Spectrometry(ICP-MS),and X-ray fluorescence spectrometry(XRF). The results indicate that these spheroidal phosphates primarily consist of multicellular algae,Megasphaera spherical fossils,and other phosphatic microbial fossils,with fluorocarbon-fluorapatite as the dominant mineral component. The relationship between algal microorganisms and phosphate formation is explored,leading to the conclusion that the proliferation of algal microorganisms in the late Doushantuo period played a vital role in phosphate precipitation,enrichment,and mineralization. These microorganisms not only absorbed phosphate into their cytoplasm,nucleus,and cell walls during life but also contributed to phosphate formation after death. Furthermore, phosphate chemical deposition in seawater was likely enhanced by microbial activity, which altered the environmental conditions of the sedimentary water.