On the long-lasting sequences of coral reef terraces from SE Sulawesi (Indonesia): Distribution, formation, and global significance

Abstract

Many islands of the eastern Indonesian Archipelago exhibit Late Cenozoic sequences of coral reef terraces. In SE Sulawesi, on the Tukang Besi and Buton archipelagos, we identified 23 islands bearing such sequences. Remote sensing imagery and field mapping combined to U/Th and 14 C dating enable to establish a chronologic framework of the reef terrace sequences from Wangi-Wangi, Buton as well as on the neighbouring, smaller islands of Ular, Siumpu and Kadatua. We identified the terraces from the last interglacial maximum (MIS 5e) at elevations lower than 20 m except on W Kadatua where it is raised at 34 ± 5 m. Such elevations yield low to moderate Upper Pleistocene uplift rates (<0.3 mm yr À1). On SE Buton Island, a sequence culminates at 650 m and includes at least 40 undated strandlines. Next to this exceptional sequence, on the Sampolawa Peninsula, 18 strandlines culminate at 430 m. Dated samples at the base of this sequence (<40 m) yield mean Middle Pleistocene uplift rates of 0.14 ± 0.09 mm yr À1. Extrapolation of these uplift rates compared to the geological setting suggests that the sequences of the Sampolawa Peninsula provide a record of sea-level high-stands for the last 3.8 ± 0.6 Ma. The sequences on SE Buton Island therefore constitute the best preserved long-lasting geomorphic record of Plio-Quaternary sea-level stands worldwide.

Dating and morpho-stratigraphy of uplifted marine terraces in the Makran subduction zone (Iran)

“…The record from GPS surveys around the Oman Sea indicates active convergence between the subducting Arabian and overriding Eurasian plates of about 20 mm yr −1 (Fig. 1a) (Bayer et al, 2006;Frohling and Szeliga, 2016;Khan et al, 2008;Masson et al, 2007;Penney et al, 2017;Peyret et al, 2009;Vernant et al, 2004;Walpersdorf et al, 2014). Although most of this convergence seems to be accommodated by reverse faults within the prism, margin-parallel normal faulting is predominant in the coastal region (Back and Morley, 2016;Dolati and Burg, 2012;Ghorashi, 1978;Harms et al, 1984;Hosseini-Barzi and Talbot, 2003;Little, 1972;Platt and Leggett, 1986;Samadian et al, 1994Samadian et al, , 1996Samadian et al, , 2004Snead, 1993).…”

“…Although most of this convergence seems to be accommodated by reverse faults within the prism, margin-parallel normal faulting is predominant in the coastal region (Back and Morley, 2016;Dolati and Burg, 2012;Ghorashi, 1978;Harms et al, 1984;Hosseini-Barzi and Talbot, 2003;Little, 1972;Platt and Leggett, 1986;Samadian et al, 1994Samadian et al, , 1996Samadian et al, , 2004Snead, 1993). The seismic activity of the MSZ is low compared to other subduction zones around the globe, although most studies agree that the potential for tsunamigenic megathrust earthquakes exists (e.g., Heidarzadeh et al, 2008;Hoffmann et al, 2013a;Pararas-Carayannis, 2006;Penney et al, 2017;Shah-Hosseini et al, 2011;Smith et al, 2013). The Middle East earthquake catalog from Zare et al (2014), ranging from 1220 BCE to 2006, shows that earthquakes of M w > 5 are less densely clustered in the MSZ than in other seismically active regions of the Middle East, like the Zagros or Caucasus.…”

“…1a). The eastern part is more active, with several thrust earthquakes occurring in the region of Pasni, notably the M w 8.1 event of 1945 (Byrne et al, 1992;Hoffmann et al, 2013b;Quittmeyer and Jacob, 1979) and a recent event of M w 6.3 in 2017 (Penney et al, 2017). In the western Makran, the two last great earthquakes are historical events from 1008 and 1483 (Ambraseys and Melville, 1982;Heidarzadeh et al, 2008), though their exact magnitude, position and focal mechanism are poorly known (Musson, 2009).…”

“…Although the western MSZ is seismically quiet, evidence of past earthquakes, activity in the eastern segment and ongoing plate convergence indicate that the plate boundary might have been accumulating elastic strain for more than 500 years. Thus, the western MSZ has the potential to produce a catastrophic earthquake (Penney et al, 2017;Rajendran et al, 2013;Smith et al, 2013).…”

“…(a) Tectonic framework on a satellite image (Bing). Yellow arrows and circles represent GPS velocities and 95 % confidence ellipses, with a fixed Arabian plate reference, compiled by Penney et al (2017) from the literature (Bayer et al, 2006;Frohling and Szeliga, 2016;Khan et al, 2008;Masson et al, 2007;Penney et al, 2017;Peyret et al, 2009;Vernant et al, 2004;Walpersdorf et al, 2014). Red lines and arrows: simplified major fault structures and relative motions.…”