Layered tektites of southeast Asia: Field studies in central Laos and Vietnam

Abstract

Abstract-We have recovered 18 kg of layered tektites from 10 tektite-bearing localities in Laos and central Vietnam, including 5 localities around the town of Muong Nong (Laos). Several of these deposits originally contained several hundred kilograms of layered tektite fragments, and one fragmented mass may have been as large as 1000 kg. This is the largest single deposit of tektites yet reported.In this region, layered tektite fragments are found in isolated clusters usually associated with a pebbly laterite horizon that is 0-1 m below the surface. Near Khe Sanh, Vietnam, we estimate the abundance of layered tektite fragments to be -100 g/m2. This is greater than five times the abundance estimated for northeast Thailand (Fiske et al., 1996).In a region that extends from northeast Thailand, through central Laos, and into central Vietnam, we found only layered tektites, which confirmed the existence of a large (>50 000 km2) subfield of the Australasian strewn field with only layered tektites. The east-west extent of the "layered-only" subfield is well constrained. but little field data exist to constrain its north-south extent.

Large Aerial Bursts: An Important Class of Terrestrial Accretionary Events

“…region having dimensions of ,40 3 130 km in the southeast corner of Northeast Thailand and found only layered tektites. Schnetzler and McHone (1996) and Fiske et al (1999) investigated sites in a band crossing southern Laos and central Vietnam, and made similar observations. The only plausible explanation that has been proposed is that the splash forms that returned to the Earth's surface in this region fell into the still molten melt and were subsumed by it.…”

“…In recent papers Fiske (1996) and Fiske et al (1999) have argued that field recovery of layered tektites from one site in Thailand and one in Vietnam (for which no actual observations are reported) is inconsistent with formation by the ponding. I was part of the field team at the Thai site.…”

“…One of the first problems recognized as inconsistent with ejecting layered tektites from craters (without production of a melt sheet) is that there are large regions of SE Asia that contain only layered tektites (Wasson, 1991;Schnetzler, 1992;Wasson et al, 1995;Fiske et al, 1999). The "splash" ("spin-form" is a better descriptive) tektites that obtained their characteristic shapes (dumbbells, teardrops) by spinning during flight are not found in these regions.…”

“…If we assume that the shape was elliptical, these dimensions yield an area of 6.9 3 10 5 km 2 ; if the distribution was patchy the area covered would have been smaller, perhaps by a factor of 2. Fiske et al (1999) estimated that the area in which all tektites are layered has an area ,5 3 10 4 km 2 , and that the remaining areas in which layered tektites are recovered also contain splash tektites. Figure 4 shows the magnetic remanence relative to the plane of the layering measured in nine SE Asian layered tektites by de Gasparis et al (1975).…”

Australasian microtektites in the South China Sea and the West Philippine Sea: Implications for age, size, and location of the impact crater

“…Our results are consistent with most of the previously proposed locations of the source crater in Indochina (Stauffer, 1978;Hartung and Rivolo, 1979;Ford, 1988;Schnetzler, 1992;Hartung and Koeberl, 1994). Recent field expeditions indicate that there is a subfield of the Australasian strewn field with only Muong Nong-type tektites but devoid of splash-form tektites (Schnetzler, 1992;Wasson et af., 1995;Schnetzler and McHone, 1996;Fiske et al, 1999). This "Muong Nong-type only" area, supposedly very close to the source 1994).…”