Origin of late Quaternary dune fields on the Southern High Plains of Texas and New Mexico

Abstract

Mostly stabilized late Holocene eolian sands on the Southern High Plains of the United States were studied to determine their origins and to assess whether present dune stability depends more strongly on sediment supply, sediment availability, or transport limitations. Geomorphic, sedimentological, and geochemical trends indicate that late Holocene dunes formed under westerly paleowinds, broadly similar to those of today. Mineralogical and geochemical data indicate that the most likely source for the sands is not the Pecos River valley, but the Pleistocene Blackwater Draw Formation, an older, extensive eolian deposit in the region. These observations suggest that new sand is supplied whenever vegetation cover is diminished to the extent that the Blackwater Draw Formation can be eroded, in agreement with modern observations of wind erosion in the region. We conclude, therefore, that Southern High Plains dunes are stabilized primarily due to a vegetation cover. The dunes are thus sediment-availability limited. This conclusion is consistent with the observation that, in the warmest, driest part of the region (where vegetation cover is minimal), dunes are currently active over a large area. Geochemical data indicate that Southern High Plains dunes are the most mineralogically mature (quartz rich) sands yet studied in the Great Plains, which suggests a long history of eolian activity, either in the dune fields or during deposition of the Blackwater Draw Formation.

Mineralogical maturity in dunefields of North America, Africa and Australia

“…Much of the Monahans field occurs upwind of the known extent of the sandy facies of the Blackwater Draw Formation (Fig. 8), although Muhs and Holliday (2001) pointed out that an older aeolian sand unit, called the Judkins Formation, occurs beneath the Monahans dunes. The Judkins Formation has not been studied in great detail, but where exposed, it appears to have many characteristics of the Blackwater Draw Formation.…”

“…On the basis of several lines of evidence, Muhs and Holliday (2001) concluded that sands of the Muleshoe dunefield are probably derived mostly from the Blackwater Draw Formation. Sands of the Muleshoe dunefield are 94 -97% SiO 2 and most have (K 2 O + Na 2 O + Al 2 O 3 ) contents of 2 -4%, which makes them highly mature mineralogically (Fig.…”

“…8). A recent study by Muhs and Holliday (2001) showed that the sands of these dunefields are very high in quartz and very low in plagioclase and Kfeldspar. Dune orientations and modern wind directions (Fig.…”

“…Map showing the distribution of aeolian sand (grey areas) in the Southern High Plains of Texas, New Mexico and Oklahoma, names of dunefields studied, and modern sand roses. Aeolian sand distribution from compilation by Muhs and Holliday (1995); sand roses are from Muhs and Holliday (2001). Also shown (thin solid line) is the distribution of the sandy or loamy facies of the Blackwater Draw Formation (from Holliday, 1989).…”

“…However, aeolian geomorphologists have not generally exploited the composition and degree of mineralogical maturity of dune sands in studies of sediment transport and aeolian landscape evolution. Studies conducted in the Great Plains region of North America indicate that there are significant differences in the degree of mineralogical maturity from dunefield to dunefield, suggesting different source sediments, transport history, or weathering history (Muhs and Holliday, 2001;Muhs et al, 1997a;Arbogast and Muhs, 2000). In this paper, the potential for using mineralogical maturity as a key to dunefield origins and history is explored, using examples from the Great Plains and southwestern deserts of the United States (Figs.…”