Low‐temperature thermal history of the McArthur Basin: Influence of the Cambrian Kalkarindji Large Igneous Province on hydrocarbon maturation

Abstract

The McArthur Basin of the North Australian Craton is one of the very few places on Earth where extensive hydrocarbons are preserved that were generated from Mesoproterozoic source rocks, prior to the development of extensive multicellular life. It is, however, unclear precisely when hydrocarbons from these source rocks matured, and if this occurred as a singular event or multiple phases. In this study, we present new apatite fission track data from a combination of outcrop and sub‐surface samples from the McArthur Basin to investigate the post‐depositional thermal history of the basin, and to explore the timing of hydrocarbon maturation. Apatite fission track data and thermal modelling suggest that the McArthur Basin experienced a basin‐wide reheating event contemporaneous with the eruption of the Cambrian Kalkarindji Large Igneous Province in the North and West Australian cratons, during which thick (>500 m) basaltic flows blanketed the basin surface. Reheating at ca. 510 Ma coinciding with Kalkarindji volcanism is consistent with a proposed timing of elevated hydrocarbon maturation, particularly in the Beetaloo Sub‐basin, and provides a mechanism for petroleum generation throughout the basin. Subsequent regional cooling was slow and gradual, most likely facilitated by gentle erosion (ca. 0.01–0.006 km/Ma) of overlying Georgina Basin sediments in the Devonian–Carboniferous with little structural reactivation. This model provides a framework in which hydrocarbons, sourced from Mesoproterozoic carbon‐rich rocks, may have experienced thermal maturation much later in the Cambrian. Preservation of these hydrocarbons was aided by a lack of widespread structural exhumation following this event.

Intracontinental Fault Reactivation in High Heat Production Areas of Central Australia: Insights From Apatite Fission Track Thermochronology

“…The most plausible scenario facilitating cooling during the Late‐Paleozoic is denudational lag as sediments were slowly eroded following gentle exhumation of the region (e.g., Gleadow & Brown, 2000; Sueoka et al., 2012) during the Alice Springs Orogeny (Ahmad & Munson, 2013; Bradshaw & Evans, 1988; Raimondo et al., 2010), which terminated sedimentation in the Georgina Basin and drove erosion of the upper units. Similar slow cooling has been proposed in the McArthur Basin (Nixon, Glorie, Hasterok, et al., 2022), which further suggests a prevalence of slow, often lagging, cooling in sedimentary basins across the NAC during the Alice Springs Orogeny, with the majority of deformation and more immediate cooling focused in Proterozoic basement around pre‐existing fault structures (Glorie, Agostino, et al., 2017; Hall et al., 2016, 2018; Nixon et al., 2021; Shaw & Black, 1991; Spikings et al., 2006).…”

“…Exhumation is contemporaneous with the ca. 390-360 Ma Pertnjara-Brewer Event of the Alice Springs Orogeny (Ahmad & Munson, 2013;Bradshaw & Evans, 1988;Jones, 1972), which is also observed in the Pine Creek Orogen (Nixon et al, 2021) and McArthur Basin (Nixon, Glorie, Hasterok, et al, 2022) in the NAC, and the Musgrave Province (Glorie, Agostino, et al, 2017;Quentin de Gromard et al, 2019) and Peake and Denison Inliers (Hall et al, 2016) in the northern South Australian Craton. Few favorably oriented major Proterozoic faults are observed within the Murphy Province, which has deprived the region of potential for significant differential exhumation and resulted in largely monotonic cooling profiles.…”

A geospatial platform for the tectonic interpretation of low-temperature thermochronology Big Data

“…These observations, in turn, allow scientists to constrain the timing and rate of a breadth of geological processes which can affect the thermal state of the crust over geological time, including the advection of mass and heat due to the growth of mountain belts, extensional basin formation, and long-term denudation 1 – 4 . Consequently, low-temperature thermochronology is an important tool for studying surface weathering processes 5 , paleoclimate 6 – 8 , and climate change 9 , 10 , as well as for constraining the formation and preservation of various natural resources, such as hydrocarbons 11 , 12 , hydrothermal and supergene ore deposits 13 – 16 , and geothermal energy fields 17 , 18 . In certain instances, such analyses can even record thermal events related to localised conductive heat transfer related to igneous activity 19 , volcanic eruptions 20 , 21 , groundwater advection 22 , 23 , hydrothermal fluid flow 24 , faulting and shear heating 25 , 26 , wildfires 27 , or meteorite formation 28 .…”

PREPRINT: A global platform solution for Big Data in low-temperature thermochronology

“…These observations, in turn, allow scientists to constrain the timing and rate of a breadth of geological processes which can affect the thermal state of the crust over geological time, including the advection of mass and heat due to the growth of mountain belts, extensional basin formation, and long-term denudation (1-4). Consequently, lowtemperature thermochronology is an important tool for studying surface weathering processes (e.g., 5), paleoclimate (e.g., [6][7][8], and climate change (e.g., 9, 10), as well as for constraining the formation and preservation of various natural resources, such as hydrocarbons (11,12), hydrothermal and supergene ore deposits (13)(14)(15)(16), and geothermal energy fields (17,18). In certain instances, such analyses can even record thermal events related to localised conductive heat transfer related to igneous activity (19), volcanic eruptions (20,21), groundwater advection (22,23), hydrothermal fluid flow (24), wildfires (25), or meteorite formation (26).…”