Triassic to Early Jurassic climatic trends recorded in the Jameson Land Basin, East Greenland: clay mineralogy, petrography and heavy mineralogy

Abstract

During the Early Triassic the Jameson Land Basin (Central East Greenland) was located around 30°N, in the Northern arid belt, but by the Early Jurassic was positioned at a latitude of approximately 50°N. This study examines the record of this transition through a largely continental succession using clay mineralogy, sedimentology, petrography and heavy mineralogy. The Jameson Land Basin is aligned north-south and is 280 km long and 80 km wide. Following an Early Triassic marine phase the basin was filled by predominantly continental sediments. The Early-to-Late Triassic succession comprises coarse alluvial clastics (Pingo Dal Formation) overlain by a succession of finegrained evaporite-rich playa/lacustrine sediments (Gipsdalen Formation), indicative of arid climatic conditions. The overlying buff, dolomitic and then red lacustrine mudstones with subordinate sandstones (Fleming Fjord Formation) record reduced aridity. The uppermost Triassic grades into dark organic-rich, and in places coaly, mudstones and buff coarse-grained sandstones of lacustrine origin that belong to the Kap Stewart Group, which spans the Triassic-Jurassic boundary, and appear to record more humid climatic conditions. Clay mineralogy analyses highlight significant variations in the kaolinite/illite ratio, from both mudstone and sandstone samples, through the Triassic and into the earliest Jurassic. Complementary heavy mineral analyses demonstrate that the variations recognised in clay mineralogy and sandstone maturity through the Triassic-Early Jurassic succession are not a product of major provenance change or the effect of significant diagenetic alteration. The observed variations are consistent with sedimentological evidence for a long-term trend towards more humid conditions through the Late Triassic to Early Jurassic, and the suggestion of a significant pluvial episode in the mid-Carnian.

Distinct petrographic responses to basin reorganization across the Triassic–Jurassic boundary in the southwestern Barents Sea

“…These observations are in line with palynological records in the Nordkapp Basin that reflect an increase in humidity towards the end of the Carnian (Hochuli & Vigran, 2010). A similar climatic trend was reported from east Greenland, where an increase in the kaolinite/illite ratio is recognized through the Late Triassic to the Early Jurassic succession (Decou, Andrews, Alderton, & Morton, 2017). Müller (2003) also recognized a long-term shift from arid/semi-arid to humid climate conditions in the northern North Sea region during the Rhaetian to Early Jurassic.…”

Structural evolution and basin architecture of the Traill Ø region, NE Greenland: A record of polyphase rifting of the East Greenland continental margin

“…The lower part of the Scoresby Land Group contains marine macrofauna that include ammonoids and bivalves. The basal contact is observed on Traill Ø and is conformable with the underlying Permian strata (Clemmensen, 1980;Christiansen, 1990;Seidler et al, 2004;Bjerager et al, 2006;Andrews et al, 2014;Decou et al, 2016).…”

The Triassic of Traill Ø and Geographical Society Ø, East Greenland: Implications for North Atlantic palaeogeography

“…The extensive Triassic strata of Jameson Land and Scoresby Land have been the subject of considerable study (Andrews, Kelly, Braham, & Kaye, 2014;Clemmensen, 1977;Clemmensen, 1978aClemmensen, , 1978bClemmensen, 1980aClemmensen, , 1980bClemmensen & Andreasen, 1976;Clemmensen, Kent, & Jenkins, 1998;Decou, Andrews, Alderton, & Morton, 2016;Grasmück & Trümpy, 1969;Kürschner & Herngreen, 2010;Perch-Nielsen, Birkenmajer, Birkelund, & Aellen, 1974). However, the relationship of these regions to the more discontinuous and poorly studied outcrops of Traill Ø and Geographical Society Ø (Figure 1) to the north is not fully understood.…”