This dataset lists the results of trace element analysis of the foraminifera Globorotalia crassaformis from Integrated Ocean Drilling Program Site U1313 (41°N, 33°W, 3426 m water depth, Expedition 306) relative to the Mid-Pleistocene Transition interval (0.55 Ma - 1.2 Ma). Site U1313 was chosen for its location in between the subtropical and subpolar gyres, along the main northward heat pathway. Sections from the primary splice were sampled every 5 cm between 26.82 adjusted composite depth in meters (amcd, Naafs et al. 2012) and 56.77 amcd at the IODP Core Repository in Bremen, Germany. The age model for this Site was updated using oxygen isotopes from benthic foraminifera (available in an accompanying dataset). Tests of G. crassaformis were picked, crushed, cleaned, and analyzed at the Institut für Geowissenschaften, Universität Heidelberg, Germany. Chemical cleaning followed the procedures described by Martin and Lea (2002) without the diethylenetriaminepentaacetic acid (DTPA) step. Fe/Ca and Mn/Ca ratios were additionally analyzed to monitor contamination by siliciclastic material and diagenetic overgrowths. Mg/Ca ratios were used to calculate deep thermocline temperatures following the species-specific equation as published by Cléroux et al. (2013). The reconstructed subsurface temperature dataset has an average resolution of 1.5 kyr and was used to calculate a vertical temperature gradient at Site U1313, interpreted as indicative of upper-ocean stratification (the calculated gradient is also available in an accompanying dataset). Cléroux et al, 2013 - doi:10.1002/palo.20050 Martin and Lea, 2002 - doi:10.1029/2001GC000280 Naafs et al., 2012 - doi10.1016/j.epsl.2011.11.026