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Cratonic Basins Chapter 30 Cratonic basins PHILIP A. ALLEN and JOHN J. ARMITAGE Department of Earth Science and Engineering, Imperial College, South Kensington Campus, London, UK ABSTRACT Cratonic basins are sites of prolonged, broadly distributed but slow subsidence of the continental lithosphere, and are commonly filled with shallow water and terrestrial sedimentary rocks. They remain poorly understood geodynamically. A number of models have been proposed that fall into families involving cooling of stretched continental lithosphere, cooling related to mantle flow (dynamic topography), densification of the underlying lithosphere due to phase changes, the surface response to magmatism and/or plume activity, and long-wavelength buckling under in-plane stresses. The timing of initiation and spatial distribution of cratonic basin formation are linked to geodynamic phases within the overall framework of plate amalgamation and super- continental break-up and dispersal. Many cratonic basins initiated in the Neoproter- ozoic and Cambrian-Ordovician. Some suites of cratonic basins originated as broad ramp-like realms of subsidence tilting down to the adjacent passive margin, and were later “individualized” by secondary processes such as, for instance, reactivation of tectonic structures during intracontinental orogeny, and the emergence of intervening arches and domes. Several different mechanisms may therefore control the geological evolution and subsidence history of cratonic basins during their long life-times. We propose that a model of low strain rate extension accompanied and followed by cooling of the underlying lithosphere satisfactorily explains the long-term subsidence history of a range of cratonic basins. However, the precise role played by dynamic topography transmitted from large-scale mantle flow in initiating or modifying the elevation history of continental interiors remains an intriguing focus for further research. Keywords: continental lithosphere; stretching; strain rate; subsidence; stratigraphy INTRODUCTION foldbelts and rift complexes. The important con- sideration is that the lithosphere behaves stably “Intracratonic basins,” “cratonic basins,” “interior (Sloss 1988). cratonic basins,” and “intracontinental sags” are Cratonic basins are characterized by prolonged, circular to oval-shaped crustal sags, located on predominantly shallow-water and terrestrial sed- stable, relatively thick continental lithosphere imentation and a gross layer-cake type of stratig- (Sloss and Speed 1974; Sloss 1988). We restrict raphy (Sloss and Speed 1974; Quinlan 1987; Sloss the use of the term “cratonic basin” to those basins 1990; Leighton et al., 1991). Their subsidence located some distance from stretched or conver- history is prolonged, occasionally marked by an gent continental margins, distinct from rifts where initial stage of relatively fast subsidence, followed a history of continental extension is unequivocal, by a period of decreasing subsidence rate (Nunn but located on a variety of crustal substrates, and Sleep 1984; Stel et al., 1993; Xie and Heller irrespective of whether they are crystalline shields 2009) (Fig. 30.1), somewhat similar to that of ocean sensu stricto, accreted terranes, or ancient basins (Sleep 1971). Cratonic basins generally lack Tectonics of Sedimentary Basins: Recent Advances, First Edition. Edited by Cathy Busby and Antonio Azor. Ó 2012 Blackwell Publishing Ltd. Published 2012 by Blackwell Publishing Ltd. 602 Cratonic Basins 603 Age (Ma) 500 400 300200 100 0 1 0 0 600 6 9 12 5 7 11 4 2 3 8 2 2 10 1 Ghadames/Berkine Basin, Algeria, (Yahi et al.) 7 Northeast German Basin (Scheck & Bayer 1999) 2 Illinois Basin, Farley Well (Bond & Kominz 1984) 8 Southwest Ordos Basin (Xie 2007) 3 Michigan Basin (Bond & Kominz 1984) 9 Paris Basin (Prijac et al. 2000) 4 4 Williston Basin, North Dakota (Bond & Kominz 1984) 10 West Siberian Basin, Russia, Urengoy well (Saunders et al. 2005) 4 tectonic subsidence (km) 5 Williston Basin, Saskatchewan (Fowler & Nisbet 1985) 11 West Siberian Basin, Russia, Samotlar-39 well (Saunders et al. 2005) (water-loaded) Backstripped 6 Paraná Basin, Brazil, CB-3 well (Oliveira 1987) 12 Paraná Basin (Zalan et al. 1990) Fig. 30.1. Compilation of intracratonic basin subsidence curves. Source: Extended From Xie and Heller (2009). well-developed initial rift phases, marked by (2) In cross-section, cratonic basins are simple arrays of extensional faults and associated graben saucers, lacking major syn-tectonic faults and half-graben, though this may be due in part to (late post-sedimentary faulting during trans- the poor seismic imaging of the base of cratonic pression/transtension is more common), with basins preserved on land. Cratonic basins are sediment thicknesses typically less than ca. located on continental lithosphere, away from 5 km, and rarely <6–7 km (as in the West Siber- the plate margin, but in some cases connected by ian, Illinois, and Parana basins). However, in a rift or failed rift zone to the ocean, as in the some cases, the circular planform shape is a Neoproterozoic Centralian Superbasin of Australia result of later compartmentalization of a pre- (Walter et al., 1995; Lindsay 2002), the Lower viously more extensive platform or ramp, as in Paleozoic Illinois and Oklahoma basins of USA the cratonic basins of north Africa, such as Al (Braile et al., 1986; Kolata and Nelson 1990), and Khufra, Murzuk, and Ghadames (Selley, 1972, the Mesozoic phase of the Chad Basin of north- 1997; Boote et al., 1998). central Africa (Burke 1976). This geometry sug- (3) The duration of subsidence is very long, mea- gests that many cratonic basins lie at the tips of sured in hundreds of millions of years (e.g., failed rifts extending into the continental plate at a Aleinikov et al., 1980), and backstripped tec- high angle from the extensional plate margin, tonic subsidence histories are commonly sub- which may be the site of former triple junctions linear to gently negative exponential (Xie and (Burke and Dewey, 1973). Heller, 2009) (Fig. 30.1). These long lifetimes of Although cratonic basins have their own indi- subsidence commonly comprise several basin viduality, which is to be expected in such long- phases separated by unconformities, giving lived basins, there are a number of prominent superimposed megasequences reflecting features common to the majority of examples. At changing patterns of the governing plate- first order, these include the following: scale tectonics. Taking the depositional mega- sequences most safely attributable to cratonic (1) The surface area enclosed by the zero isopach of basin subsidence, and neglecting long periods the basin-fill is commonly circular or elliptical, of non-deposition at megasequence bound- and large, with surface areas ranging from the aries, the cratonic basins of North America relatively small Anglo-Paris Basin (105 km2), accumulated sediment at rates of 20 to 30 m À through the large Hudson Bay (1.2 Â 106 km2) Myr 1 (Sloss 1988), which is extremely slow and Parana basins (1.4 Â 106 km2) to the giant compared to rifts, failed rifts, young passive Centralian Superbasin (2 Â 106 km2) and West margins, foreland basins, and strike-slip basins Siberian Basin (3.5 Â 106 km2) (Leighton and (Allen and Allen 2005), but relatively fast com- Kolata, 1990, p. 730; Sanford, 1987; Walter pared to the adjacent platforms. Laterally et al., 1995, p. 173; Vyssotski et al., 2006). equivalent platformal areas, such as the 604 Part 5: Plate Interior Basins and Basin Types Transcontinental Arch of USA, accumulated remained as cratonic basins throughout their his- ca. 1 km if sediment between Cambrian and tory but have existed long enough to have been À Permian, at a rate of 3–4 m Myr 1 (Sloss 1988). strongly affected by several tectonic mechanisms (4) Stratigraphy is predominantly terrestrial to of subsidence and uplift. Consequently, shallow-water, indicating that sedimentation there may be a primary mechanism for basin kept pace with tectonic subsidence through- formation, and different secondary mechanisms out. Cratonic basin megasequences commonly for later modification. start as a broad regional tilting of the continent, A large number of mechanisms have been as in the latest Proterozoic-Early Ordovician invoked to explain cratonic basins (see Hartley “Sauk” sequence of east-central North America and Allen, 1994, table 1; and review by Klein, (Sloss, 1963, 1988) (discussed below) and the 1995). Models, which are partly overlapping, Early Paleozoic (pre-Silurian) of north Africa include the following: (Selley, 1997). However, facies belts in bull’s- eye and teardrop patterns (exemplified by the . Thermal contraction following heating (Haxby Silurian carbonates and evaporites of the et al., 1976; Sleep and Sloss, 1980; Kaminski and Michigan Basin; Nurmi and Friedman, 1977) Jaupart, 2000) indicate that the circular outline of some . Localized extension related to magmatic upwell- cratonic basins is a primary, syndepositional ing that may be associated with plume activity feature and is not a result simply of post- (Klemme, 1980; Keen, 1987; Klein and Hsui, sedimentary tectonic deformation dissecting 1987; Ziegler and van Hoorn, 1989; Ziegler, 1990; a previously more extensive depocenter. Neumann et al., 1992; Zhao et al., 1994) Cratonic basins in low paleolatitudes are com- . Deep crustal phase changes (De Rito et al., 1983; monly dominated by chemical sediments, Fowler and Nesbit, 1985; Helwig, 1985; Artyushkov showing that particulate sediment supply and Bear, 1990; Artyushkov,
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