Record of Neotectonics and Deep Crustal Fluid Circulation Along the Santa Fe Fault Zone in Travertine Deposits of the Lucero Uplift, New Mexico, USA

Abstract

Abstract Travertine deposits preserve an invaluable record of both ancient and modern fluid flow. The goal of this study is to reconstruct spatial and temporal patterns in travertine deposition associated with tectonic and climatic controls along the Lucero Uplift in New Mexico, USA. Uranium‐series ages of travertine deposits in the Lucero Uplift range from 0.94 ± 0.01 to 592 ± 110 ka, indicating that travertine formation has been episodically active since at least ∼600 ka. We find minimal evidence to attribute glacial and interglacial cycles to travertine formation in the Lucero Uplift. δ13C values in travertine deposits range from 2‰ to 9‰ (Vienna Pee Dee Belemnite), δ18O values range from 21‰ to 25‰ (Vienna Standard Mean Ocean Water). Positive correlation between travertine δ13C and δ18O values indicate travertine formation is closely associated with various degrees of CO2 degassing. 87Sr/86Sr values in travertine deposits range from 0.714 to 0.717 and (234U/238U)i values exhibit a remarkably wide range from 3.6 to 9.3, indicative of fluid‐rock interaction during deep crustal circulation in more radiogenic basement rocks. Reconstructed δ13C, δ18O, and (234U/238U)i values in the inferred deep fluid sources showed systematic variations with travertine formation ages, while 87Sr/86Sr values remain relatively constant. Based on dating of undeformed travertine deposits, which overlie tilted Santa Fe Group units, and high (234U/238U)i we infer that the Santa Fe fault has not produced a ground‐rupturing earthquake within the last 490 ± 52 to 592 ± 110 ka (2σ). Our study suggest that travertine formation is driven by fluid flow facilitated by tectonic and mantle structures.

Keywords

• fluid mixing
• jemez lineament
• rio grande rift
• SR isotopes
• travertine
• U‐series