Linking a Triassic delta to present-day catchments Linking an Early Triassic delta to antecedent topography: Source-to-sink study of the southwestern Barents Sea margin Christian Haug Eide1,†, Tore G. Klausen1, Denis Katkov2, Anna A. Suslova2, and William Helland-Hansen1 1Department of Earth Science, University of Bergen, Box 7803, 5020 Bergen, Norway 2Petroleum Department, Moscow State University, Moscow, 119991, Russia ABSTRACT Tana catchment was formed close to the occurred in this area since the Carboniferous Permian-Triassic transition, and that the (Bugge et al., 1995; Riis, 1996; Gudlaugsson Present-day catchments adjacent to sedi- Triassic delta system has much better res- et al., 1998; Hall, 2015). The present-day Fen- mentary basins may preserve geomorphic ervoir properties compared to the rest of noscandian Barents Sea coast (Fig. 1) is likely elements that have been active through long Triassic basin infill. This implies that land- a close approximation to the long-term bound- intervals of time. Relicts of ancient catch- scapes may indeed preserve catchment ge- ary between the successive sedimentary basins ments in present-day landscapes may be in- ometries for extended periods of time, and located in the Barents Sea and the eroding up- vestigated using mass-balance models and it demonstrates that source-to-sink tech- lands of the Fennoscandian Shield (e.g., Wors- can give important information about up- niques can be instrumental in predicting the ley, 2008; Hall, 2015). The area has also largely land landscape evolution and reservoir dis- extent and quality of subsurface reservoirs. escaped extensive modification by Quaternary tribution in adjacent basins. However, such glaciations (Riis, 1996; Ebert et al., 2015; Hall methods are in their infancy and are often INTRODUCTION et al., 2015) and is therefore an ideal location difficult to apply in deep-time settings due to in which to test and develop models for linking later landscape modification. An understanding of the mass balances from ancient sedimentary systems to catchments. The southern Barents Sea margin of N catchments to ultimate sediment sinks is impor- Because distinct sediment source areas may Norway and NW Russia is ideal for investi- tant because they illuminate the links between produce sand types with dramatically different gating source-to-sink models, because it has long-term mass fluxes and filling of sedimentary reservoir properties, it may be critical in res- been subject to minor tectonic activity since basins, and the patterns of erosion and denuda- ervoir exploration settings to understand the the Carboniferous, and large parts have tion that record Earth history (Bhattacharya et amount of sediment produced from different eluded significant Quaternary glacial ero- al., 2016; Helland-Hansen et al., 2016). It is also catchments, because this will help to predict the sion. A zone close to the present-day coast has important in order to predict sedimentary envi- distribution and extent of suitable sandstones. likely acted as the boundary between basin ronments and their link to catchments in areas The Norwegian Barents Sea is an area of on- and catchments since the Carboniferous. with limited data (e.g., Sømme et al., 2009a), going petroleum exploration, but the Triassic Around the Permian-Triassic transition, a since it increases predictability in reservoir strata generally show poor reservoir properties. large delta system started to prograde from and hydrocarbon exploration (Martinsen et al., This is mainly because the majority of the sand- the same area as the present-day largest river 2010). Investigating sediment mass balances for stones were sourced from the young and active in the area, the Tana River, which has long source-to-sink systems in deep time (≤108 yr) Uralian orogen through an enormous fluvial been interpreted to show features indicating is challenging because factors such as tectonic system, stretching over 1.2 × 103 km from the that it was developed prior to present-day regime and climate are poorly constrained, Urals in the SE to at least Svalbard in the NW topography. We performed a source-to-sink catchments are largely eroded, and resolution of (Figs. 1, 2B, and 3; Bergan and Knarud, 1993; study of this ancient system in order to inves- dating methods is uncertain (e.g., Romans et al., Mørk, 1999; Glørstad-Clark et al., 2010; Klau- tigate potential linkages between present-day 2016; Helland-Hansen et al., 2016). However, in sen et al., 2015). This led to the deposition of geomorphology and ancient deposits. the Early Triassic of the Barents Sea, several of mineralogically immature and mudstone-rich We investigated the sediment load of these hampering issues are alleviated: Biostrati- sediments, and, due to long transport and de- the ancient delta using well, core, two- graphic dating has a relatively high resolution creasing gradients, extraction of coarse grains dimensional and three-dimensional seis- (~1 m.y.) due to rapid evolutionary diversifica- before the fluvial system reached the present mic data, and digital elevation models to tion after the Permian-Triassic extinction event Norwegian sector. investigate the geomorphology of the on- (e.g., Chen and Benton, 2012); the climate dur- Several authors have briefly described a sedi- shore catchment and surrounding areas. ing this period has been the subject of several mentary system with more favorable reservoir Our results imply that the present-day studies, as it was a time of major climatic shifts properties prograding from the Fennoscandian (Péron et al., 2005; Sellwood and Valdes, 2006; Shield to the south into the Finnmark Platform Svensen et al., 2009; Hochuli and Vigran, 2010; in the Barents Sea Basin during the earliest In- †[email protected] Sun et al., 2012); and minor tectonic change has duan (earliest Triassic; Fig. 2; Hadler-Jacobsen GSA Bulletin; January/February 2018; v. 130; no. 1/2; p. 263–283; https://doi.org/10.1130/B31639.1; 13 figures; 1 table; Data Repository item 2017267; published online 15 August 2017. Geological Society of America Bulletin, v. 130, no. 1/2 263 © 2017 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Eide et al. fault zone is the main boundary on the eastern Finnmark Platform (Fig. 2A; Roberts and Lip- pard, 2005). From the Ordovician through the Devonian, the Fennoscandian Shield was buried by foreland basin sediments related to the Cale- donian orogeny (490–390 Ma), which were later eroded (Larson et al., 1999, 2006; Kohn et al., 2009). Several NE-SW–oriented rift zones were formed in the Barents Sea Basin during the mid- dle Carboniferous (Gudlaugsson et al., 1998). This affected sediment transport networks, e.g., by funneling a major delta system out a half- graben along the present-day Porsangerfjorden (Fig. 2A; Bugge et al., 1995). During the late Carboniferous, the Barents Sea Basin entered an intracratonic sag phase and was dominated by regional subsidence (Gudlaugsson et al., 1998). From the late Carboniferous to the latest Perm- ian, the Barents Sea Basin was the site of a re- gional carbonate platform, with minor clastic in- put from nearby landmasses (Bugge et al., 1995; Samuelsberg et al., 2003; Colpaert et al., 2007). Gradual northward drift of the continent during the Permian led to gradual cooling and a change from tropical reefs to cool-water spiculitic car- bonates in the Kungurian (“middle” Permian; e.g., Worsley, 2008). Major changes occurred around the Permian- Triassic transition, both in terms of climate and regional tectonic setting. A marked lithological change occurs across the western part of the ba- sin close to this boundary, from the cool-water Figure 1. Paleogeographic map showing regional setting of the study carbonates and spiculitic shales of the Tem- area in the Early Induan (Early Triassic). Based on a variety of sources, pelfjorden Group to the shale-dominated Sas- including Cocks and Torsvik (2006), McKie and Williams (2009), sendalen Group (Fig. 3; e.g., Mørk et al., 1982; Reichow et al. (2009), and Miller et al. (2013). Wignall et al., 1998; Vigran et al., 2014). A ma- jor rise in global average temperature of ~15 °C occurred at this time, leading to the greatest et al., 2005; Glørstad-Clark et al., 2010; Hen- three-dimensional (3-D) seismic, core, and well mass extinction recorded (Sun et al., 2012). This riksen et al., 2011a). This system appears to data, (2) to investigate mass-balance and source- event has been linked to major eruptions and gas have been point sourced, and it is fully con- to-sink-relationships of this system to constrain release in the Siberian Traps large igneous prov- strained by high-quality two-dimensional (2-D) catchment properties, (3) to investigate possible ince (Svensen et al., 2009; Reichow et al., 2009; seismic data. The system has been sampled by links to relict onshore catchment geometries, Burgess and Bowring, 2015). three available shallow cores (Mangerud, 1994; (4) to discuss the impact of this analysis on res- This time also coincided with the start of Bugge et al., 1995) and industry well logs, and ervoir prediction in the Barents Sea, and (5) to progradation of a major sedimentary system it is therefore well suited for a source-to-sink demonstrate the applicability of source-to-sink (prodelta–delta–delta plain) of the Havert For- analysis. Furthermore, the Tana and Alta River models to reservoir exploration in general. mation out of the Uralian foreland basin and systems directly onshore in northernmost Nor- Kara Sea into the Barents Sea Basin (Fig. 3C; way have long been interpreted to show numer- GEOLOGICAL BACKGROUND Puchkov, 2009; Glørstad-Clark et al., 2010; ous antecedent features (NE-flowing tributary Norina et al., 2014). At the same time, around channels deeply incised into the generally SSE- The northern Fennoscandian margin has the Permian-Triassic transition (Vigran et al., dipping topographic trend of N Fennoscandia, acted as a boundary between the mainly emer- 2014), smaller sedimentary systems started to and a highly asymmetric tributary pattern; gent Fennoscandian Shield and the Barents Sea prograde from the Fennoscandian Shield into Fig.