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A detailed lithostratigraphic and geochemical analysis was performed on a 13.77 m sequence consisting of a succession of limestones, argillaceous limestones and marlstones at the El Pujal section in the Organya Basin of the south-central Spanish Pyrenees. Biostratigraphic analysis reveals the presence of the foraminifer Leupoldina cabri positioning the sequence within OAE 1a. Corroborating evidence from stable carbon isotope data permits the correlation of the El Pujal section with other Tethyan sections, namely Roter Sattel (Switzerland), Cismon (Italy) and El Pui (Spain) to within carbon isotope segment C5. Geochemical results reveal periodic increase of redox sensitive trace elements (RSTEs: V, Ni, Co, Cr, Cu, Mo), biolimiting (P, Fe) and terrestrially derived elements (Al, Si, Ti) at argillaceous limestone and marlstone intervals, concurrent with episodes of enhanced organic matter preservation (TOC >1.18%). Further evidence from microfacies characterized by higher pyrite concentration, impoverished benthic fauna and lower degree of bioturbation are in accord with geochemical proxies. Biomarker data shows n-alkanes distributions ranging from nC(10) to nC(31), suggesting that the organic matter (OM) is a mixture of in-situ produced and terrestrially derived. Calculated average chain length (ACL (nC25-nC33)) shows lower values in intervals associated with argillaceous limestones and marlstones, suggesting wetter climate during these periods. The results imply that fluvial influences controlled by regional hydrologic variability related to climatic fluctuations probably exacerbated the already sluggish basinal conditions through the development of density stratification in the water column. Integration of the data from the El Pujal section shows that changes in paleoproductivity, terrigenous input, and redox conditions characterize the deposition of OAE la in the Organya Basin without the hallmark of an anoxic phase. Conditions remained similar to those recorded in the preceding sequence at El Pui, thus revealing continuous deposition of OM under impoverished oxygen conditions, punctuated by episodes of dysoxia. (C) 2018 Elsevier Ltd. All rights reserved.