“…In this contribution, a study of the oxygen, carbon and strontium isotope composition of calcite veins and their host sedimentary rocks enables us to constrain the paleohydrological system evolution of the Sheep Mountain Anticline (SMA), a Laramide, basement‐cored anticline in Wyoming, United States (Figure 1a) [ Hennier , 1984; Forster et al , 1996; Stanton and Erslev , 2004; Stone , 2004; Erslev , 2005]. Even if the geometry of the underlying thrust is still debated [ Hennier and Spang , 1983; Forster et al , 1996, Stanton and Erslev , 2004; Stone , 2004, Fiore Allwardt et al , 2007, Amrouch et al , 2010a], the structure and timing of the fracture network in this fold is well constrained [ Harris et al , 1960; Johnson et al , 1965; Bellahsen et al , 2006a, 2006b; Amrouch et al , 2010a; Savage et al , 2010], and allows us to accurately place our geochemical study into a reliable spatiotemporal context related to the evolution of the fold. Our primary goal is to constrain the paleofluid system at the fold scale, and to relate the evolution of this system to the evolution of the fold.…”