TY  - JOUR
A1  - Nomosatryo, Sulung
A1  - Tjallingii, Rik
A1  - Henny, Cynthia
A1  - Ridwansyah, Iwan
A1  - Wagner, Dirk
A1  - Tomás, Sara
A1  - Kallmeyer, Jens
T1  - Surface sediment composition and depositional environments in tropical Lake Sentani, Papua Province, Indonesia
JF  - Journal of Paleolimnology
N2  - Tropical Lake Sentani in the Indonesian Province Papua consists of four separate basins and is surrounded by a catchment with a very diverse geology. We characterized the surface sediment (upper 5 cm) of the lake's four sub-basins based on multivariate statistical analyses (principal component analysis, hierarchical clustering) of major element compositions obtained by X-ray fluorescence scanning. Three types of sediment are identified based on distinct compositional differences between rivers, shallow/proximal and deep/distal lake sediments. The different sediment types are mainly characterized by the correlation of elements associated with redox processes (S, Mn, Fe), carbonates (Ca), and detrital input (Ti, Al, Si, K) derived by river discharge. The relatively coarse-grained river sediments mainly derive form the mafic catchment geology and contribution of the limestone catchment geology is only limited. Correlation of redox sensitive and detrital elements are used to reveal oxidation conditions, and indicate oxic conditions in river samples and reducing conditions for lake sediments. Organic carbon (TOC) generally correlates with redox sensitive elements, although a correlation between TOC and individual elements change strongly between the three sediment types. Pyrite is the quantitatively dominant reduced sulfur mineral, monosulfides only reach appreciable concentrations in samples from rivers draining mafic and ultramafic catchments. Our study shows large spatial heterogeneity within the lake's sub-basins that is mainly caused by catchment geology and topography, river runoff as well as the bathymetry and the depth of the oxycline. We show that knowledge about lateral heterogeneity is crucial for understanding the geochemical and sedimentological variations recorded by these sediments. The highly variable conditions make Lake Sentani a natural laboratory, with its different sub-basins representing different depositional environments under identical tropical climate conditions.
KW  - Tropical lake
KW  - Lacustrine sediment
KW  - XRF analysis
KW  - Multivariate
KW  - statistics
Y1  - 2022
U6  - https://doi.org/10.1007/s10933-022-00259-4
SN  - 0921-2728
SN  - 1573-0417
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Sebag, David
A1  - Garcin, Yannick
A1  - Adatte, Thierry
A1  - Deschamps, Pierre
A1  - Menot, Guillemette
A1  - Verrecchia, Eric P.
T1  - Correction for the siderite effect on Rock-Eval parameters
BT  - Application to the sediments of Lake Barombi (southwest Cameroon)
JF  - Organic geochemistry : the international journal for rapid publication of current research in organic geochemistry and biochemistry
N2  - Originally developed for use in the petroleum industry, Rock-Eval pyrolysis is a technique commonly applied to lake sediments to infer paleoenvironmental reconstructions. The standard Rock-Eval parameters provide information on the amount of total organic and inorganic carbon (TOC and MinC, respectively), and are usually interpreted as proxies for the source (aquatic or terrestrial) of the primary production of organic matter (Hydrogen Index vs Oxygen Index). Although this method usually provides valuable evidence, the common presence of siderite in tropical lake sediments can alter the primary signal of the sedimentary organic matter (SOM). Indeed, the CO2 and CO released by the pyrolysis of siderite are integral to the calculation of the SOM-related standard Rock-Eval parameters. In this study, we analyze sediments from a core collected in the Lake Barombi (southwest Cameroon) and describe the impact of siderite on standard Rock-Eval parameters. We propose a workflow that allows standard Rock-Eval parameters to be corrected, based on the analysis of thermograms. The proposed corrections provide siderite-effect-free parameters, accurately reflecting the changes in sedimentary organic matter composition. (C) 2018 Elsevier Ltd. All rights reserved.
KW  - Organic geochemistry
KW  - Rock-Eval pyrolysis
KW  - Van Krevelen diagram
KW  - Siderite
KW  - Tropical lake
KW  - Western Central Africa
Y1  - 2018
U6  - https://doi.org/10.1016/j.orggeochem.2018.05.010
SN  - 0146-6380
VL  - 123
SP  - 126
EP  - 135
PB  - Elsevier
CY  - Oxford
ER  -