24 Devonian of New York II: A New, Extensive Volume on The North American Standard Section

Monday, 21 March 2022
8:00 AM - 12:00 PM
Commonwealth Salon 2

CHAPTER 7: TULLY FORMATION AND PRE-FRASNIAN GENESEE GROUP SUCCESSION

Paper number: 24-1
Program: Symposia Sessions
Time: 8:00 AM – 8:20 AM

Authors

Abstract

The carbonate-dominated Tully Formation and coeval nearshore siliciclastic Gilboa Formation are the type expression of the North American provincial Taghanic Stage (Polygnathus ansatus-“Ozarkina” semialternans zones), recording the multi-phased Global Taghanic Biocrisis. The Tully-Gilboa interval is overlain by basin-filling, progradational siliciclastic deposits of Acadian Tectophase 4 represented by the Geneseo Formation-Lodi Member succession (Genesee Group). This lower, pre-Frasnian, part of the Genesee Group, corresponds to the sequential hermanni, disparilis, and norrisi conodont zones.

The Tully Limestone in central New York, anomalously composed of clean, micritic limestone, contrasts greatly with underlying Hamilton siliciclastic facies and overlying Geneseo basinal black shale deposits. Taghanic biotas are characterized by appearance of the distinctive Old World Tully fauna and demise of the long-ranging, endemic Hamilton Fauna during an episode of warming and transgression. An apparent cooling event in mid-Tully time permitted a brief, dramatic return of the Hamilton Fauna, followed by stepwise marine deepening, which initiated the classic Taghanic Onlap event during late Tully deposition. This widespread drowning event terminated the Hamilton Biota, allowing for gradual appearance of the lower diversity Genesee Fauna in an evolving foreland basin. Tully shelf deposition in central New York was particularly influenced by carbonate influxes from northward cratonic sources and syndepositional cratonic flexural events, particularly in mid-Tully time. Post-Tully Geneseo, deposition was dominated by widespread transgressive overspread of basinal anoxia associated with flexural foreland basin development as shown by diachronous westward onlap of basal Geneseo black muds as zonally indicated by the pyrite-dominated Leicester lag deposit flooring the Geneseo.

This interval is divided into 3rd and 4th-order T-R cycles: third-order Sequence Giv-4, corresponds to the uppermost Moscow Formation and lower Tully Formation, and Giv-5, corresponds to the upper two thirds of the Tully Formation and the entire Geneseo Formation. The diachronous base of Sequence Giv-5 is a widespread erosive surface widely identified as the “Taghanic Unconformity.”

Geological Society of America Abstracts with Programs. Vol. 54, No. 3

doi: 10.1130/abs/2022NE-374466

© Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.