ALBERT

Description: Benthic foraminiferal stable carbon isotope records from the South Atlantic show significant declines toward more "Pacific-like" values at ~7 and ~2.7 Ma, and it has been posited that these shifts may mark steps toward increased CO2 sequestration in the deep Southern Ocean as climate cooled over the late Neogene. We generated new stable isotope records from abyssal subantarctic Pacific cores MV0502-4JC and ELT 25-11. The record from MV0502-4JC suggests that the Southern Ocean remained well mixed and free of vertical or interbasinal d13C gradients following the late Miocene carbon shift (LMCS). According to the records from MV0502-4JC and ELT 25-11, however, cold, low d13C bottom waters developed in the Southern Ocean in the late Pliocene and persisted until ~1.7 Ma. These new data suggest that while conditions in the abyssal Southern Ocean following the LMCS were comparable to the present day, sequestration of respired CO2 may have increased in the deepest parts of the Southern Ocean during the late Pliocene, a critical period for the growth and establishment of the Northern Hemisphere ice sheets.

Description: During the Cretaceous, widespread black shale deposition occurred during a series of Oceanic Anoxic Events (OAEs). Multiple processes are known to control the deposition of marine black shales, including changes in primary productivity, organic matter preservation, and dilution. OAEs offer an opportunity to evaluate the relative roles of these forcing factors. The youngest of these events-the Coniacian to Santonian OAE 3-resulted in a prolonged organic carbon burial event in shallow and restricted marine environments including the Western Interior Seaway. New high-resolution isotope, organic, and trace metal records from the latest Turonian to early Santonian Niobrara Formation are used to characterize the amount and composition of organic matter preserved, as well as the geochemical conditions under which it accumulated. Redox sensitive metals (Mo, Mn, and Re) indicate a gradual drawdown of oxygen leading into the abrupt onset of organic carbon-rich (up to 8%) deposition. High Hydrogen Indices (HI) and organic carbon to total nitrogen ratios (C:N) demonstrate that the elemental composition of preserved marine organic matter is distinct under different redox conditions. Local changes in d13C indicate that redox-controlled early diagenesis can also significantly alter d13Corg records. These results demonstrate that the development of anoxia is of primary importance in triggering the prolonged carbon burial in the Niobrara Formation. Sea level reconstructions, d18O results, and Mo/total organic carbon ratios suggest that stratification and enhanced bottom water restriction caused the drawdown of bottom water oxygen. Increased nutrients from benthic regeneration and/or continental runoff may have sustained primary productivity.

Description: Scanning XRF elemental count data for silicon, sulfur, potassium, calcium, titanium, iron, bromine, and coherent scatter from Santa Barbara Basin cores SPR0901-04BC, MV0508-33JPC, MV0508-21JPC, and MV0508-29JPC, measured by cumulative depth [cm] in cps using an ITRAX XRF core scanner. This has been divided into: core 04BC; intervals A, B, C, and D for 33JPC; C1, C2, and D for 21JPC; D for 29JPC; whole core 33JPC, and whole core 29JPC. The data set also contains PC1s (first principal component of these elements after principal component analysis; [score]) for each division .The annual time [a] is provided for each measurement in 04BC, and intervals A, B, C, and D for 33JPC. The composite PC1 [score] for the Termination V core suite and the composite depth [cmcd] is included. Quantitative aluminum [%], calcium [%], iron [%], potassium [%], magnesium [%], manganese [%], sodium [%], sulfur [%], and titanium [%] compositions for Termination V sediments measured using ICP-AES or ICP-MS. Foraminiferal d18O [per mil VPDB] from planktic G. bulloides and N. pachyderma and benthic Uvigergina spp. and Bolivina spp. by cumulative and composite depth.

Description: This dataset provides geochemical data for the Santa Barbara Basin, CA. Sediment was analyzed from sediment core SPR901-03KC, five river sites and a sediment trap. River locations correspond to the locations in Napier et al. (2019; doi:10.1130/B32035.1). The geochemical data include the δ13C, δ15N, Total Organic Carbon (TOC), Total Nitrogen (TN), molar carbon: nitrogen ratios (C/N), Mass Accumulation Rates (MAR), and n-alkane concentration by chain length. These measurements were labelled by depth in the sediment core and categorized by type of event. Event type (flood, turbidite, drought, background) were previously determined Scanning X-Ray Fluorescence (Hendy et al., 2015: doi:10.1016/j.quaint.2015.01.026). The age model for the sediment core was previously determined by Hendy et al. (2013: doi:10.1016/j.quaint.2015.01.142). This data was used to determine the impact of episodic flood, turbidite, and prolonged drought on the organic carbon burial in the Santa Barbara Basin, CA.