Table 1 Summary of the reported mechanical, rheological and erosional factors controlling formation of a triangle zone (passive roof thrust duplex). The table shows how individual parameters favour either the initiation of an active or a passive roof thrust. These factors are compared to the External Dinarides fold-and-thrust belt
Parameter | Active roof thrust | Passive roof thrust | Likelihood | Details of regional geological setting |
|---|---|---|---|---|
Heterogeneities in the mechanical stratigraphy (Couzens-Schultz et al., 2003; Couzens & Wiltschko, 1996) | Low | High | High | Mainly carbonates in the overburden low grade metamorphic shales in the Paleozoic, no data from the southern External Dinarides |
Upper detachment (Costa & Vendeville, 2002; Couzens-Schultz et al., 2003; Dean et al., 2013; Jamison, 1996) | Weak | Strong | High | Mechanical difference east and west of the Split-Karlovac Fault likely favoured the along-strike contrasting style of deformation |
Influence of pre-existing structure/Lateral facies changes (Albanese & Sulli, 2012; Erickson, 1995; Malz et al., 2016; Mohn et al., 2014) | Low | High | High | Middle Triassic half graben (Lawrence et al., 1995; Smirčić et al., 2020), Lemeš Basin (Velić et al., 2002; Vitzthum et al., 2022) |
Low | High | Possible | Pre-triangle zone crustal thickening, due to nappe stack | |
Differential Erosion & Syn-tectonic deposits (Erdős et al., 2015; Fillon et al., 2013; Mugnier et al., 1997) | Low | High | Low | No erosion data, but high erosion within the Velebit Mtn., no syn-tectonic deposits in the frontal Velebit part |
Shortening rate (Couzens-Schultz et al., 2003) | Low | High | Excluded | No data; excluded, higher amount of shortening in the active roof thrust segment (Balling et al., 2021b) |
Buttress (backstop) (Albanese & Sulli, 2012; Couzens-Schultz et al., 2003; Erickson, 1995; Jamison, 1996) | No | Yes | Excluded | Not known in the Adriatic Sea and considered unlikely |