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Empowering conventional Rock-Eval pyrolysis for organic matter characterization of the siderite-rich sediments of Lake Towuti (Indonesia) using End-Member Analysis
Ordonez L.a, Vogel H.b, Sebag D.d, Ariztegui D.a, Adatte T.d, Russell J.M.e, Kallmeyer J.f, Vuillemin A.a,g, Friese A.f, Crowe S.A.h, Bauer K.W.h, Simister R.h, Henny C.i, Nomosatryo S.i, Bijaksana S.j
a Department of Earth Sciences, University of Geneva, Geneva, 1205, Switzerland
b Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, 3012, Switzerland
c Normandie Univ, UNIROUEN, UNICAEN, CNRS, M2C, Rouen, 76000, France
d Institute of Earth Surface Dynamics, Geopolis, University of Lausanne, Lausanne, Switzerland
e Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, 02912, United States
f GFZ German Research Centre For Geosciences, Potsdam, D-14473, Germany
g Ludwig-Maximilians-Universität München, Department of Earth & Environmental Sciences, Paleontology & Geobiology, Munich, 80333, Germany
h Department of Microbiology and Immunology and Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
i Research Center for Limnology, Indonesian Institute of Sciences (LIPI), Bogor, 16911, Indonesia
j Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132, Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]© 2019 The AuthorsQualitative and quantitative changes of organic and carbonate carbon in sedimentary records are frequently used to reconstruct past environments, paleoproductivity and sediment provenance. Amongst the most commonly used proxies are Total Organic Carbon (TOC), Mineral Carbon (MinC), as well as Hydrogen (HI) and Oxygen Indices (OI) of organic matter (OM). Rock Eval pyrolysis enables the assessment of these quantitative and qualitative parameters with a single analysis. This is achieved through transient pyrolysis of the samples up to 650 °C followed by combustion up to 850 °C, with hydrocarbons, CO and CO2 measured during the thermal decomposition of both OM and carbonate minerals. Carbonate minerals with low thermal cracking temperatures, such as siderite (<400 °C), can induce significant matrix effects which bias the TOC, MinC and OI Rock-Eval parameters. Here we assess the applicability of End-Member Analysis (EMA) as a means of correcting Rock-Eval thermograms for siderite matrix effects. For this, we performed Rock-Eval pyrolysis on sideritic sediments of Lake Towuti (Indonesia). New thermal boundaries were constrained in Rock-Eval thermograms using EMA to limit siderite matrix effects and improve TOC, MinC and OI calculations. Our approach allowed us to: (1) evaluate the influence of siderite matrix effects on Rock-Eval thermograms; (2) properly exploit a Rock-Eval dataset to characterize the type and sources of OM in siderite-rich sediments and (3) identify the OM behind degradation and mineralization processes. The Rock-Eval dataset revealed sediments with a substantial amount of refractory OM, especially in those where TOC is high and HI characteristic of autochthonous biomass. These results, associated to alternative indices used to assess OM preservation, suggest that refractory OM is residually enriched following strong degradation of labile compounds. Finally, relatively labile and refractory organic fractions may be consumed in the formation of siderite during this sequential process of OM mineralization.[/vc_column_text][vc_empty_space][vc_separator css=".vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}"][vc_empty_space][megatron_heading title="Author keywords" size="size-sm" text_align="text-left"][vc_column_text]Endmembers,Mineralization process,Qualitative parameters,Quantitative changes,Rock-Eval pyrolysis,Siderite,Total Organic Carbon,Tropical lakes[/vc_column_text][vc_empty_space][vc_separator css=".vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}"][vc_empty_space][megatron_heading title="Indexed keywords" size="size-sm" text_align="text-left"][vc_column_text]End-Member Analysis,Mineral carbon,Organic matter,Rock-Eval pyrolysis,Siderite,Thermal analysis,Tropical lake[/vc_column_text][vc_empty_space][vc_separator css=".vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}"][vc_empty_space][megatron_heading title="Funding details" size="size-sm" text_align="text-left"][vc_column_text][{'$': 'The Towuti Drilling Project was partially supported by grants from the International Continental Drilling Program , the US National Science Foundation , the German Research Foundation , the Swiss National Science Foundation ( 20FI21_153054/1 and 200021_153053/1 ), Brown University , Genome British Columbia , and the Ministry of Research, Technology, and Higher Education (RISTEK). PT Vale Indonesia, the US Continental Drilling Coordination Office, the GeoForschungs-Zentrum Potsdam and DOSECC Exploration Services are acknowledged for logistical assistance to the project. This research was carried out with permission from the Ministry of Research and Technology (RISTEK), the Ministry of Trade of the Republic of Indonesia, and the Natural Resources Conservation Center (BKSDA) and Government of Luwu Timur of Sulawesi. We thank the valuable comments and suggestions of F. Baudin and Ch. Giguet-Covex to an early version of this manuscript as well as co-Editor in Chief S. Rowland.'}, {'$': 'The Towuti Drilling Project was partially supported by grants from the International Continental Drilling Program, the US National Science Foundation, the German Research Foundation, the Swiss National Science Foundation (20FI21_153054/1 and 200021_153053/1), Brown University, Genome British Columbia, and the Ministry of Research, Technology, and Higher Education (RISTEK). PT Vale Indonesia, the US Continental Drilling Coordination Office, the GeoForschungs-Zentrum Potsdam and DOSECC Exploration Services are acknowledged for logistical assistance to the project. This research was carried out with permission from the Ministry of Research and Technology (RISTEK), the Ministry of Trade of the Republic of Indonesia, and the Natural Resources Conservation Center (BKSDA) and Government of Luwu Timur of Sulawesi. We thank the valuable comments and suggestions of F. Baudin and Ch. Giguet-Covex to an early version of this manuscript as well as co-Editor in Chief S. Rowland. L. Ordoñez (LO), D. Ariztegui (DA), D. Sebag (DS), and H. Vogel (HV) designed the study; LO sampled at LacCore, conducted laboratory analyses, led the writing of the manuscript and designed the figures. J. M. Russell (JMR), S. Bijaksana (SB), HV, and M. Melles (MM) designed and led the Towuti Drilling Project. LO, HV, JMR, SB, A. Friese (AF), J. Kallmeyer (JK), S. A. Crowe (SAC), K. W. Bauer (KWB), R. Simister (RS), A. Vuillemin (AV), and S. Nomosatryo (SN) participated in fieldwork and LO, DA, HV, JMR, JK, and AV participated in core opening. JMR and HV developed the sediment stratigraphy. T. Adatte (TA) contributed with XRD facilities and provided external data. All authors were involved in discussions about the data and contributed to writing and improving the manuscript. Members of the Towuti Drilling Project provided scientific, technical, and logistical support during field sampling and core opening.'}][/vc_column_text][vc_empty_space][vc_separator css=".vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}"][vc_empty_space][megatron_heading title="DOI" size="size-sm" text_align="text-left"][vc_column_text]https://doi.org/10.1016/j.orggeochem.2019.05.002[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]