Continental strike-slip rifts and their stratigraphic signature: application to the Bangong/Nujiang zone (Tibet) and the South Penninic zone (Alps)

Abstract

Our literature studies show that the thermal regime along continental strike-slip rifts is inconspicuous and that they are "low-volcanicity rifts" at best. Along with that, young continental strike-slip rifts exhibit no signs of major thermally controlled doming. We suggest that the larger the strike-slip component of a rift is, the less likely major thermal doming is causally associated with the rift zone. Since vertical lithosphere movements are reflected in the stratigraphic record of a rifted area, different rift modes (strike-slip, dip-slip) may be distinguished by analyzing the relevant sequences. Two ancient and especially suitable strike-slip rift margins in Tethyan mountain belts, the Bangong/Nujiang zone of Tibet and the South Penninic zone of the Alps, were analyzed with regard to their uplift history. The results confirm recent regional rift models which indicate in both cases that rifting was dominated by strike-slip. The stratigraphic approach may provide significant clues as to the mode of paleorifting when structural data are unavailable.

Tectonic and sedimentary basin evolution of the eastern Bangong–Nujiang zone (Tibet): a Reading cycle

“…Because Scythian terrestrial deposits are restricted to only the Qiangtang block and the Scythian is of only short duration (Harland et al 1990: 4 million years; Haq and Van Eysinga 1998: 5 million years), we don't attribute the Scythian emergence to a major, rift-related regional uplift. Because rifting evidently occurred, but was not accompanied by major pre-and/or synrift doming, as is typical for grabentype rifts, we concluded that Triassic continental separation was due to transtension (Mattern et al 1998). As of the Late Triassic, major facies differences were recognized on both sides of the BNZ by Chang et al (1989), who concluded that the Lhasa and Qiangtang blocks formed one continuous platform until the Late Triassic when the DNB opened between them.…”

“…Because the rift flank sequences indicate transtensional basin formation (Mattern et al 1998) and because transpression played a major role in the destruction of the oceanic basin floor, the DNB's evolution represents a Reading cycle (see Introduction ;Reading 1980;Mitchell and Reading 1989) despite tectonic events unique to the DNB's cycle.…”

“…Subsequently, Yu et al (1991) interpreted the BNZ as a pull-apart basin zone. Studying the stratigraphy of both the Qiangtang and Lhasa blocks that lack indication of rift-related thermal doming, as is typical for graben-type rifts, Mattern et al (1998) concluded that the early Dongqiao-Naqu basin (DNB) was a strike-slip-dominated rift.…”

Radiolarian age constraints on Mesotethyan ocean evolution, and their implications for development of the Bangong–Nujiang suture, Tibet

“…It is variously regarded as a collisional suture (Coulon et al 1986), a continent-arc or continent-forearc collision zone overprinted by a continent-continent collision (Pearce & Deng 1988), a rift (Taner & Meyerhoff 1990), a strike-slip dominated rift (for the Dongqiao-Nagqu basin) (Mattern et al 1998), a strike-slip basin (Schneider et al 2003), or a back-arc basin (Haines et al 2003). More recently, Guynn et al (2006) proposed accretion of a microcontinent to the Qiangtang terrane in the Early-Mid-Jurassic (Amdo basement).…”