Retallack Gregory J
Department of Earth Sciences, University of Oregon, Eugene, Oregon, United States of America.
PLoS One. 2025 Jun 24;20(6):e0325547. doi: 10.1371/journal.pone.0325547. eCollection 2025.
The Cambrian and Ediacaran sequence of California and Nevada is rife with unconformities, paleovalleys, paleosols, and fluvial facies. This study confirms shallow marine environments for grey stromatolitic dolostone and shale of northern localities (Mt Dunfee and Westgard Pass), but fluvial red sandstones and siltstone of southern localities (Johnnie, Eagle Peak, Emigrant Pass, Donna Loy, and Cadiz) include paleosols as evidence for coastal plain and fluvial environments. Three marine transgressions into the southern localities, were in Ediacaran Johnnie Formation, earliest Cambrian Manykodes pedum zone, and Early Cambrian Olenellus trilobite zone. The southern locations have paleosols with Ediacaran fossils Ernietta, Pteridinium, Swartpuntia, and Hallidaya in growth position, as evidence that these vendobiont fossils were non marine. The paleosols include aridland Gypsids and Calcids, as well as weakly developed soils, with diagnostic LYREE enrichment, and low boron content of paleosols. Northern Ediacaran marine rocks, in contrast, are limestones with Cloudina and Wyattia, and shales with Conotubus and Wutubus. Identical marine and non-marine facies and biotas are also known from Ediacaran and Cambrian rocks of Namibia. Ediacaran marine wormlike fossils (Wormworld) were ecologically distinct and geographically separated from non-marine, sessile, vendobionts (Mattressland).
加利福尼亚州和内华达州的寒武纪和埃迪卡拉纪层序中存在大量不整合面、古河谷、古土壤和河流相。本研究证实了北部地区(邓菲山和韦斯加德山口)灰色叠层石白云岩和页岩为浅海环境,但南部地区(约翰尼、鹰峰、移民山口、唐娜·洛伊和卡迪兹)的河流相红色砂岩和粉砂岩包含古土壤,作为海岸平原和河流环境的证据。三次海侵进入南部地区,分别发生在埃迪卡拉纪约翰尼组、寒武纪最早期的多尼科德斯足带和寒武纪早期的油栉虫三叶虫带。南部地区的古土壤中,埃迪卡拉纪化石埃尔涅塔、蕨叶迹、斯瓦特蓬提亚和哈利代亚处于生长位置,证明这些文德生物化石并非海洋生物。这些古土壤包括干旱地区的石膏土和钙质土,以及发育较弱的土壤,具有诊断性的轻稀土元素富集,且古土壤硼含量较低。相比之下,北部埃迪卡拉纪海相岩石为含有克劳德管虫和怀亚特管虫的石灰岩,以及含有圆锥管和无管的页岩。纳米比亚的埃迪卡拉纪和寒武纪岩石中也发现了相同的海相和非海相岩相及生物群。埃迪卡拉纪海洋蠕虫状化石(蠕虫世界)在生态上与非海洋、固着的文德生物(床垫世界)不同,且在地理上相互分隔。