Quantitative Biofacies Analysis to Identify Relationships and Refine Controls on Paleosol Development, Prince Creek Formation, North Slope Alaska, USA

James R Bonelli,Peter P Flaig

doi:10.3390/geosciences11110460

Abstract

Late Cretaceous coastal plain deposits of the Prince Creek Formation (PCF) offer a rare glimpse into an ancient, high-latitude, arctic greenhouse ecosystem for which there is no modern analog. Here, we employ quantitative biofacies analysis to explore the spatio-temporal variability in PCF palynomorph and microbiota assemblages from nine paleosol horizons exposed along the Colville River, North Slope, Alaska. Biofacies results provide insight into paleoenvironmental controls on the coastal plain ecosystem. Cluster and ordination analyses recognize five biofacies and the following two assemblage types: (1) fern and moss dominated assemblages and (2) algae dominated assemblages. Ordination arrays biofacies along environmental gradients related to soil moisture and marine influence. Fern and moss dominated biofacies from regularly water-logged paleosols along lake and swamp margins on the lower delta plain clearly segregated from algae dominated assemblages of periodically drier levee-overbank paleosols. These results support previous interpretations from the sedimentology, paleopedology, and geochemistry of PCF paleosols that suggest that fluctuations in the water table, related to seasonal river discharge and variations in topography and drainage, controlled soil development and vegetation growth across the coastal plain. This quantitative biofacies-based approach provides an independent predictive tool and cross-check for interpreting environmental conditions along any ancient coastal ecosystem.

Highlights

The Upper Cretaceous (Maastrichtian) Prince Creek Formation (PCF) of northernAlaska (Figure 1) offers a rare glimpse into an ancient, high-latitude, arctic greenhouse ecosystem
The stratigraphic and paleoenvironmental framework of the PCF coastal plain has been established through studies of continental through shallow marine deposits exposed along the Colville River [13,21,22,23]
The purpose of this study is to quantitatively analyze palynomorph and microbiotic been established through studies of continental through shallow marine deposits assemblages contained within the PCF paleosol horizons described previously exposed by Flaig along

Summary

Introduction

The Upper Cretaceous (Maastrichtian) Prince Creek Formation (PCF) of northernAlaska (Figure 1) offers a rare glimpse into an ancient, high-latitude, arctic greenhouse ecosystem. The PCF contains the richest concentration of dinosaur fossils of any high latitude location across the globe. Non-avian dinosaurs including small therapods, hypsilophodontids, pachycephalosaurs, ceratopsians, and hadrosaurs thrived along the PCF coastal plain in association with coniferous and broad-leaf deciduous forests and an angiosperm shrub dominated understory. This ecosystem persisted under profound seasonality, a polar light regime, and a cool temperate paleoclimate for which there is no modern analog [21,22]. The stratigraphic and paleoenvironmental framework of the PCF coastal plain has been established through studies of continental through shallow marine deposits exposed along the Colville River [13,21,22,23]. The PCF comprises the most proximal deposits of a Late Cretaceous to Paleocene progradational succession [24,25,26]

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