Finding the Gaps: Using biostratigraphy to determine precise relationships between two Late Triassic Formations in West-Central Nevada Judith Ocampo & Lydia S. Tackett, Department of Earth Sciences

The Problem: New York Canyon A sequence of limestones in two places in Nevada are Late Triassic in (NYC) Results age, but we don’t know if they coincide (overlap in time), or how much time is represented at each. 500µ Judith’s This problem can be solved with biostratigraphy. NYC 4 conodont

29,210µ

NYC 3 This study Channell et al. (2003) Mockina bidentata: Fig 3 #53 Late Norian age Channell et al. (2003) Fig.3 NYC 2 Summary of Results Modi ed from Hallam and Wignall 2000 Field Localities:New York Canyon and Berlin Ichthyosaur Late Norian 22,352µ Judith’s Channell et al. - NYC contained conodonts of Questions NYC 1 conodont Late Norian age from both sam- ples 1. What part of the Late Triassic is represented in New York Canyon? 500µ We will identify conodont species from the beginning and end of the section to bracket the - BISP contained conodonts This study Mockina bidentata: Channell et al.(2003) time Late Norian age Fig.3 # 28 common to the Middle Norian 2. Were New York Canyon and Berlin Ichthyosaur deposited at the same time or was there a depositional hiatus? Implications/Conclusion: We will identify the conodonts at the top of the older section (BISP) and the bottom of the 1. Only Late Norian conodonts are BISP 7 younger section (NYC) to compare the ages which will bracket a possible gap present in the sampled section of 500µ 19,304µ New York Canyon, meaning that Methods/ Steps BISP 6 This study Channell et al.(2003) the section is Late Norian in age - Mockina carinata: Fig.3 # 12 What is biostratigraphy? 2. BISP contained Middle Norian The differentiation of sedimen- Middle Norian age tary rock units on the basis of conodonts at the top and NYC their fossils. BISP 5 Each Conodont species contained Late Norian conodonts at -What is a conodont? has multiple elements! the bottom, indicating that there is The jaw like apparatus of an a gap (depositional hiatus) ancient worm like animal BISP 4 1) Broke rock samples into pieces Reference 2) Dissolved rock with 1:10 ratio of Channell, J.E.T., Kozur, H.W., Sievers, R., et al., 2003. acetic acid to water. Limestone Carnian-Norian biomagnetostratirgaphy at Silická Brezová (Slovakia): correlation to other Tethyan sections matrix dissolves, conodonts remain BISP 3 and to the Newark Basin. Palaeogeography, Palaeoclima- 3) Used 250µ seive because con- Early to Middle Norian tology, Palaeoecology vol. 191 pg 65-109. odonts are larger than 250µ 4) Conodont picking BISP 2 Acknowledgements 5) Specimens were imaged with a Will Berelson for SEM help and overall scanning electron microscope or genius, Frank Corsetti for poster inspira- binocular microscope with tion WISE for funding, Carlie Pietsch for BISP 1 attached camera 5m poster help, and Emily Mortazavi for orga- 6) Specimens identifed through nization. comparison with published images Berlin Ichthyosaur State Park (BISP)