Mass Wasting and Uplift on Crete and Karpathos During the Early Pliocene Related to Initiation of South Aegean Left-Lateral, Strike-Slip Tectonics
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Mass wasting and uplift on Crete and Karpathos during the early Pliocene related to initiation of south Aegean left-lateral, strike-slip tectonics W.J. Zachariasse† Stratigraphy and Paleontology group, Faculty of Geosciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands D.J.J. van Hinsbergen Paleomagnetic Laboratory “Fort Hoofddijk,” Faculty of Geosciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, The Netherlands A.R. Fortuin Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands ABSTRACT nal Miocene unconformity. Hiatuses in some related either to paroxysm (Fortuin, 1978), places in Crete and on Karpathos, however, regional uplift and erosion of the lower Pliocene Reconstruction of the vertical motion his- indicate that slope failures continued to occur (Meulenkamp et al., 1979b), submarine sliding tory of Crete and Karpathos (southeastern although on a smaller scale and less frequent due to foundering of fault blocks during the Aegean region, Greece) from the Messinian than before. early Pliocene (Peters, 1985), or slope failures to Recent revealed a previously poorly docu- Connecting the change from subsidence to during deep submergence at the beginning of the mented late Messinian phase of strong sub- uplift in the earliest Pliocene with the onset of Pliocene of a rejuvenated relief that was shaped sidence with rates of 50–100 cm/k.y. followed left-lateral, strike-slip tectonics in the south- during the terminal Miocene (van Hinsbergen by stasis during the fi rst 250 k.y. of the Plio- eastern Aegean arc would make this major and Meulenkamp, 2006). The discussion thus cene and then by uplift of 500–700 m during strike-slip system much older (by ~2 m.y.) seems to revolve, to a large extent, around the the late early to early middle Pliocene. Uplift than the generally accepted age of middle to question of whether the emplacement of mass continued up to Recent albeit at a slower late Pliocene. A recently postulated scenario fl ows followed from uplift during the early Plio- pace and at different rates in different areas. of “Subduction Transform Edge Propagator” cene or from foundering of fault blocks either The lower Pliocene in Crete and Karpathos is (STEP) faulting to explain the south Aegean during early Pliocene or terminal Miocene. characterized by widespread occurrences of strike-slip system predicts rates, distribution, Subsidence of the Cretan basins seems to have mass-wasting deposits, which were emplaced and amount of uplift as rebound to south- occurred until at least the latest Miocene (van over a period of time spanning the fi rst 1.35 westward retreat of the subducted slab along Hinsbergen and Meulenkamp, 2006). The uplift m.y. of the Pliocene. The origin of these mass- a transform fault zone that is in line with of Crete was placed in the middle of Pliocene wasting deposits has long been enigmatic our fi ndings on Crete and Karpathos and time (Fortuin, 1978; Meulenkamp et al., 1994; but is here related to uplift which started in explains the absence of compressional struc- van Hinsbergen and Meulenkamp, 2006) with Crete as early as ca 5 Ma. It is suggested that tures associated with the uplift, as well as the local emergence as early as ca 3.4 Ma (ten Veen the beginning uplift following strong subsid- ongoing southwestward motion of Crete. and Kleinspehn, 2003), which seems to take the ence of various fault blocks until late in the edge off the claim of very early Pliocene uplift. Messinian is related to the onset of south Keywords: Crete, vertical motion history, early Data on vertical motions during this time span Aegean strike-slip faulting. We postulate that Pliocene mass wasting, Messinian, geodynam- are lacking for Karpathos. small-scale tilting of fault blocks by trans- ics, Aegean. Uncertainties with respect to the origin of the tensional strike-slip faulting and increased widespread lower Pliocene mass fl ows on Crete seismic activity generated slope failures and INTRODUCTION and Karpathos thus concentrate on two major subsequent sliding of poorly cemented lower points. The fi rst one focuses on the age range Pliocene and uppermost Messinian Lago The lower Pliocene in Crete and Karpathos of the mass fl ows: are individual mass fl ows Mare sediments overlying the terminal Mio- (Greece) is unusual in that sediments of this separated in time, and if so, what is their precise cene erosional unconformity. The absence of age are in many places represented by unstrati- age range? Secondly, did early Pliocene basins mass-wasting deposits after 3.98 Ma, while fi ed, mass fl ow deposits of typically several experience strong subsidence or uplift, or stasis, uplift continued, is most likely the result of tens of meters thick and made up of ill-sorted following strong subsidence until and including progressive compaction and cementation of mixtures of deep marine, lower Pliocene marls the Messinian? Solving these issues is a prereq- the increasingly deeper buried Lago Mare and components of older Neogene strata (up to uisite to any meaningful discussion that would and lower Pliocene sediments, thereby pre- several meters across) fl oating in marly matrix. center on the question of how mass wasting fi ts venting slope failure to a depth of the termi- These unusual deposits were fi rst described in in with the vertical motion history of Crete and some detail from the Ierapetra region by For- Karpathos. If mass wasting is causally related †E-mail: [email protected] tuin (1977), and since then their origin has been to vertical motions, then how did this process GSA Bulletin; July/August 2008; v. 120; no. 7/8; p. 976–993; doi: 10.1130/B26175.1; 8 fi gures; 1 table; Data Repository item 2008050. 976 For permission to copy, contact [email protected] © 2008 Geological Society of America Late Miocene and Pliocene history of Crete EURASIA BLACK SEA CAUCASUS NAFZ Figure 1. Map of the Aegean SM GREECE T 40 NA region. HT—Hellenic Trench; KFZ—Kephalinia Fault Zone; MI—Milos; NAT—North TURKEY Aegean Trough; NAFZ—North KFZ C y s Anatolian Fault Zone; RB— c l a d e Mi Rhodos Basin; PST—Pliny Rhodos M HT SAMC Karpathos and Strabo Trenches; SAMC— e RB d Crete i t Southern Aegean Metamorphic e r r a ARABIA n PST Complex; SM—Sea of Mar- e an Ridge mara. AFRICA 30 N 0200400 600 20 25 30 35 40 45 come about? And if not, what are the alterna- GEOLOGIC SETTING ment of a large E-W–trending, supra-detach- tives? In this paper, we present for the fi rst time ment basin on Crete accommodating the fl uvial- a detailed description of the lithology, strati- Crete and Karpathos are emerged parts of the lacustrine sediments of the Males river system graphic context, and depositional environment Aegean arc located to the north of the Medi- (van Hinsbergen and Meulenkamp, 2006). This of these lower Pliocene mass fl ows in Crete terranean Ridge, the surface expression of the early supra-detachment basin dates back to and Karpathos along with an accurate chronol- accretionary complex, that marks the modern 12–11 Ma and became increasingly fragmented ogy. Furthermore, we will quantify Messinian Hellenic subduction zone (Fig. 1). The Aegean in the course of the late Miocene by dominantly to middle Pliocene vertical motions for differ- arc represents the southern termination of the N-S–striking faults refl ecting arc-parallel exten- ent areas in Crete and Karpathos by calculating Aegean lithosphere and has migrated south- sion associated with ongoing outward motion depositional depth values for samples from 38 ward several hundreds of kilometers relative to of the Aegean arc (ten Veen and Meijer, 1998; sections and outcrops spanning the critical time Eurasia since Eocene times as a result of pro- Fassoulas, 2001; van Hinsbergen and Meulen- span after correcting for sediment infi ll and cesses including south(west)ward rollback of kamp, 2006). Finally, some time between the eustasy. It should be noted, however, that a subducting African lithosphere and associated latest Miocene and the late Pliocene, within the reconstruction of the vertical motion history is backarc extension, gravitational collapse, and same time span as the uplift of Crete, a large greatly hampered by the Messinian Salinity Cri- westward extrusion of Anatolia (Dewey and system of left-lateral, strike-slip faults including sis, which refers to a short period in the history Şengör, 1979; Le Pichon et al., 1982; Meu- those forming the prominent offshore Pliny and of the Mediterranean (5.96–5.33 Ma; Krijgsman lenkamp et al., 1988; Jacobshagen, 1994; Fas- Strabo trenches was formed in the southeast- et al., 1999) of massive salt extraction followed soulas et al., 1994; Meijer and Wortel, 1997; ern sector of the Aegean arc. The net result of by desiccation and refi lling during the earliest Cianetti et al., 2001; Jolivet, 2001; Armijo et activity along this fault system is transpression Pliocene at 5.332 Ma (Lourens et al., 2004). In al., 2004, Kreemer and Chamot-Rooke, 2004). resulting in uplift and counterclockwise rota- particular, the removal of a signifi cant portion North-south–directed, syn- and post-orogenic tion in the south Aegean region (Le Pichon et of the Messinian sediment cover by drawdown- extension via low-angle detachments exhumed al., 1979; Peters and Huson, 1985; Duermeijer related erosion during the terminal Messin- metamorphic complexes in the Aegean region et al., 1998; Mascle et al., 1999; Woodside et ian complicates the reconstruction of vertical since the Oligocene (Lister et al., 1984; Gau- al., 2000; ten Veen and Kleinspehn, 2003; van motions within the critical time span.