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The terrestrial Permian-Triassic boundary event bed is a nonevent

¹Department of Geology, Colby College, Waterville, Maine 04901, USA
²Council for Geosciences, Private Bag x112, Silverton, Pretoria 0001, South Africa

View larger version (46K): [in this window] [in a new window]   Figure 1. Locality map showing Bethulie region, South Africa, and study sites on the Bethel, Heldenmoed, and Fairydale farms (3026AD TampasFontein 1:50000 1980 Quad map [Pretoria, South Africa, Council for Geosciences]). Dashed lines mark farm boundaries. Stars are discussed laminite intervals and are illustrated in Figures 2 and 3; circles are correlatives not discussed. Contour interval = 20 m.

View larger version (103K): [in this window] [in a new window]   Figure 2. Bethel and Heldenmoed farms heterolithic units. Outcrops are identified by stars in Figures 1 and 3. A: Laminites on Bethel Farm (30°25'321''S, 26°15'918''E) as described by Ward et al. (2000) and Smith and Ward (2001). Moschorhinos is reported from the nodule horizon (Retallack et al., 2003). Scale in decimeters. B: Lateral correlative on the Bethel Farm (30°25'105''S, 26°15'859''E), where tabular and low-angle cross-bedded sandstone dominates. Scale in decimeters. C: Lateral correlative on the Heldenmoed farm (30°24'999''S, 26°15'846''E), where green-gray siltstone is heavily weathered and there is no evidence for sandstone-siltstone couplets. D: Laminite interval on the Heldenmoed farm (30°25'003''S, 26°5'875''E). Scale in decimeters. E: Lateral correlative of laminite interval (30°25'062''S, 26°16'006''E) on Heldenmoed farm where medium-grained tabular and planar cross-bedded sandstone are overlain by green-gray coarse siltstone. Scale in decimeters. F: Smith and Botha's (2005, Fig. 3) EPP (End-Permian Paleosol) identified on the Bethel farm that is stratigraphically below the Heldenmoed laminites. Neveling stands within white circle marking stratigraphic position of datum used to correlate across this side of valley. Vertical arrow indicates Early Triassic recovery faunal interval as recognized by Botha and Smith (2006).

View larger version (32K): [in this window] [in a new window]   Figure 3. Contrasting correlations of laminite intervals across the Bethel and Heldenmoed farms. EPP—End-Permian Paleosol. A: Correlation proposed by Ward et al. (2000) and subsequent workers with the laminite unit interpreted as unique isochronous, basin-wide event bed deposited in response to the Permian-Triassic extinction. B: Empirical correlation based on facies relationships with respect to traceable bounding surfaces of sandstone datums that overlie the laminites on the Bethel and Heldenmoed farms.

View larger version (55K): [in this window] [in a new window]   Figure 4. Relationship of End-Permian paleosol (EPP) concretions as reported by Retallack et al. (2003, their Fig. 3A) to the laminite interval at Lootsberg Pass (31°50'952''S, 24°52'525''E). A: Photomosaic of EPP nodules in channel-form siltstone overlying heterolithic unit. Arrows mark erosional contact between units. B: Line illustration of facies relationships in A. Laterally tracing the sandstone overlying the nodules reveals that interbedded sandstone and siltstone couplets are stratigraphically equivalent to nodules rather than overlying them.