Low-latitude ?upper Barremian-lower Aptian palynoflora and paleovegetation of the Biyadh Formation (Arabian Plate, eastern margin of northern Gondwana): evidence for a possible cold snap

A palynological analysis of core and cuttings samples from successions assigned to the Biyadh Formation of Saudi Arabia in the Arabian Gulf (eastern margin of northern Gondwana) revealed diverse and well-preserved palynological assemblages including bryophyte and fern spores, gymnosperm and flowering plant pollen, dinocysts, and acritarchs. Palynological data corroborates earlier geological and strati-graphic models, indicating a ?late Barremianearly Aptian age. The fluctuations of dinocyst abundance and diversity proved extremely useful to detect fine-scale sea-level changes in carbonate platforms with episodic terrigenous inputs. In agreement with current understanding of dinocyst paleoenvironmental distribution trends, Cribroperidinium and Aptea? vannophora are restricted to inner neritic/?fluvial-influenced settings, while Spiniferites and Trichodinium have been confirmed as more open marine wa-ter (middle/outer neritic) indicators. The composition of the terrestrial assemblages is dominated by fluvially-transported spores, mainly released by ferns and probable tree ferns. The overall floral composition is considered to reflect a seasonal, humid, climate punctuated by episodic droughts. Recurrent increases in abundance of wind-pollinated cheirolepid and Araucariaceae pollen, observed in assemblages otherwise characterized by low dinocyst content, are interpreted to represent sea-level falls and basinward expansion/migration of conifer-dominated coastal vegetation. The abundance of the dinocysts Cepadinium variabilis and Pseudoceratium nohrhansenii sp. nov., previously recorded at higher latitudes, is interpreted to reflect the invasion of cooler/colder water masses, confirming a significant ? latest Barremian/early Aptian global cold episode, possibly related to the OAE1a event. The following new dinocyst taxa are described: Pseudoceratium nohrhansenii sp. nov. and Protobatioladium alhajrii sp. nov. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A palynological analysis of samples from the Biyadh Formation in the Arabian Gulf revealed diverse and well-preserved palynological assemblages, supporting earlier geological and stratigraphic models and indicating a late Barremian-early Aptian age. The fluctuations of dinocyst abundance and diversity were useful for detecting fine-scale sea-level changes in carbonate platforms. The composition of terrestrial assemblages reflects a seasonal, humid climate with episodic droughts.