Carbon cycle
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The data set comprises rhenium isotope compositions, rhenium concentrations, total organic carbon concentrations, and titanium concentrations measured from bulk rock digestions of the Eagle Ford Shale in South Texas, USA. The samples were obtained from coeval strata recovered in drill core Innes-1 and outcrop sections DR5 and DR12. The project aimed to compare the isotopic composition of Re before and after oxidative weathering. Rhenium concentrations were measured by isotope dilution, using liquid-liquid (alcohol) extraction and measurement by MC-ICP-MS. Rhenium isotopes were measured after a 3-stage column purification procedure using MC-ICP-MS. MC-ICP-MS measurements were made with the addition of a tungsten spike to correct for instrumental mass fractionation. Total organic carbon concentrations were measured by Rock-Eval pyrolysis (Rock-Eval VI) and Ti concentrations by ICP-AES.
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Three Published Papers; Thomson et al CMP 2014 - Origin of Sub-Lithospheric diamonds from the Juina-5 Kimberlite (Brazil): constraints from Carbon Isotopes and Inclusion Compositions http://dx.doi.org/10.1007/s00410-014-1081-8. Thomson et al Nature 2016 - Slab melting as a barrier to deep carbon subduction http://dx.doi.org/10.1038/nature16174 Burnham et al 2015 - Stable Isotope evidence for Crustal Recycling as recorded by superdeep Diamonds http://dx.doi.org/10.1016/j.epsl.2015.10.023 NERC grant abstract: Natural diamonds are formed at high pressures and temperatures deep within the Earth's interior. When diamonds form, probably from carbonate-rich fluids and melts in the mantle, they sometimes encapsulate small pieces of the minerals that occur at great depth in the Earth. These are called mineral inclusions. The diamonds are then transported from Earth's deep mantle to the surface in uncommon magmas called kimberlites. Diamonds that contain these mineral inclusions are very rare, and offer a truly unique glimpse into what is an otherwise inaccessible portion of the Earth. Some very rare inclusions provide direct samples of lithologies present in the mantle transition zone (400 - 660 km) and the lower mantle (>660 km) - these are often called superdeep diamonds. The chemistry of the inclusions along with mineral phase relations yield important information about the kinds of lithologies they originated in, and constrain the conditions of diamond formation and the depth at which kimberlite magmas form. Thus, superdeep diamonds are very important for studying the types of materials that occur in the deep Earth, for elucidating deep mantle processes, and for understanding how carbon is cycled from the surface to the mantle and back to the surface again - the deep carbon cycle. For example, some diamonds contain materials that are very similar to those occurring near the earth's surface, such as minerals akin to oceanic crust or sediments, and these often have carbon isotopic compositions akin to organic carbon - although this is a controversial subject. From this, we can conclude that surface materials can be transported to great depth, helping to constrain models of mass transfer in Earth by mantle convection. Further, by dating when the diamonds formed, for example by dating of inclusions, we can effectively place time constraints in the geodynamic processes involved in diamond formation and uplift in the mantle. Inclusion-bearing diamonds suitable for study are very hard to come by. We are very fortunate to be in possession of several large suites (over 200 inclusion-bearing diamonds in all!) of diamonds from kimberlite pipes in the famous Juina region of Brazil, a region known for its superdeep diamonds. Our previous study on diamonds from the Juina region has yielded some fascinating results, and has led to a model of material recycling beneath Brazil that we have recently published in the journal Nature and in Contributions to Mineralogy and Petrology. We now wish to extend our investigations by studying new suites of diamonds from Juina to test our current model, and to make high-pressure temperature experiments that will allow us to determine at what depths the inclusions formed and equilibrated, and will provide information needed to constrain the rates at which diamonds were transported in the solid-state mantle, possibly in a mantle plume. Here, we propose a three-year project for a comprehensive mineralogical, geochemical, isotopic and experimental investigation of these unique diamonds and their mineral inclusions.
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Global warming during the Palaeocene-Eocene Thermal Maximum (PETM, ~56 Ma) is commonly interpreted as being driven by massive destabilization of carbon from surficial sedimentary reservoirs. If correct, this has important implications for the amplification of future fossil fuel emissions via carbon-climate feedbacks. In our study we provided new paired records of boron and carbon isotope changes in the ocean that questions this long-held interpretation. Our data are implemented in an Earth system model to reconstruct the unfolding carbon cycle dynamics across the event. Strong evidence for a larger (>10,000 PgC) and on average isotopically heavier (> -17‰) carbon source leads us to identify volcanism associated with the North Atlantic Igneous Province as the main driver of the PETM. We also find that although organic carbon feedbacks with climate played a more minor role in driving the event than previously thought, organic matter burial was important in ultimately sequestering this carbon and driving the recovery of the system. Data presented in this data set comprise geochemical elemental, as well as boron, carbon and oxygen isotopic data from surface dwelling foraminifera Morozovella Subbotina. Alongside the boron isotopic data we also provide reconstructed surface water pH with corresponding uncertainties for our preferred pH reconstruction.
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Geochemical and isotopic data presented here cover the Paleocene-Eocene Thermal Maximum (~56 Ma ago) and were produced to assess the degree of carbon cycle perturbations, ocean acidification and the origin of the emitted carbon added to the atmosphere-ocean system during this major carbon cycle perturbation event. For further details on the analytical approach please refer to the original publication (Gutjahr et al., 2017, Nature). Data contained within the two tables comprise foraminiferal carbonate based stable boron, carbon and oxygen isotopic results from DSDP Site 401 located within the Bay of Biscaye in the NE Atlantic (Table 1). This table also contains B/Ca, Mg/Ca and Al/Ca data from the same samples. Depth in core is presented alongside two alternative relative age models setting ages in relation to the Carbon Isotope Excursion observed during the Paleocene Eocene Thermal Maximum. Table 2 contains high-resolution bulk carbonate stable carbon and oxygen isotopic results that were produced to establish a new age models for this core.
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The dataset consists of eleven spreadsheet tabs, each tab containing lipid biomarker palaeothermometry (air temperature reconstructions) and bulk organic carbon isotope data from individual lignites that are known to stratigraphically span the Cretaceous-Palaeogene (K-Pg) boundary. Uncalibrated, raw biomarker distributions (glycerol dialkyl glycerol tetraethers; GDGTs) are provided, as well as the calculated calibration outputs. Site coordinates are: West Bijou, Colorado (39°34'14'N, 104°18'09'W), Sussex, Wyoming (43°39'40"N, 106°19'06"W), Pyramid Butte, North Dakota (46°25'03'N, 103°58'33'W), Hell Creek Road, Montana (47°31'35"N, 106°56'23"W), Rock Creek West, Saskatchewan (49°02'20"N, 106°34'00"W), Wood Mountain Creek, Saskatchewan (49°25'20"N, 106°19'50"W), Frenchman Valley, Saskatchewan (49°20’56"N, 108°25’05"W), Knudesn’s Coulee, Alberta (51°54’27"N, 113°02’57"W) Griffith’s Farm, Alberta (51°54’47"N, 112°57’51"W), Coal Valley Cores (GSC CV-42-2, Cores 1 and 2), Alberta (53°05’02"N, 116°47’ 40"W) Police Island, Northwest Territories (64°52'42"N, 125°12'33"W).