ZusammenfassungNach herk6mmlichen plattentektonischen Vorstellungen soll eine inaktive Subduktionszone am nordwesflichen Kontinentalrand von Sabah liegen. Reflexionsseismische Mei~da-ten der BGR zeigen jedoch, daf~ hier autochthone kontinentale Kruste mit einer oligoz~inen-friihmioz~inen Karbonatplattform progressiv yon einem allochthonen Gesteinsverband ikberschoben wird. Fortschreitender Zusammenschub seit dem frfihen Mioz~in fiihrte zur Anlage yon vier Deformationszonen: Tekonische Schuppen (Zone III); zwei iibereinander geschobene Verschuppungssysteme (Zone IV); G~irtel mit mehrphasiger Deformation (Zone V) und Durchspief~ungsstrukturen (Zone VI). AbstractWidely accepted plate tectonic models suggest that an inactive subduction zone lies along the north-west continental margin of Sabah. In contrast, interpretation of reflection seismic data acquired by BGR shows an autochthonous continental terrane comprising an Oligocene to Early Miocene carbonate platform being progressively overthrust by an allochthonous rock complex. Progressive compression resulted in the development of four structural zones: Imbrica'ced thrust sheets (Zone III); two thrust sheet systems one on top of the other (Zone IV); a complex zone with multiphase deformation (Zone V); and piercement ridges (Zone VI). R6sum6Les modules g6odynamiques que l'on admet habituellement comportem une zone de subduction inactive le long de la marge continentale nord-occidentaIe de Sabah. Toutefois, des mesures de sismique-r6flexion ex6cut6es par le BGR font apparakre qu'~ cet endroit, une cro~lte continentale autochtone, comportant une plateforme carbonat6e oligoe~ne 6omioc~ne, est chevauch6e progressivement par un complexe allochtone. La compression, qui s'est manifest& progressivement depuis le Miocene inf6rieur, a engendr~ quatre zones structurales: un ensemble d'6cailles tectoniques (zone III); deux syst~mes de lames tectoniques charri6s l'un sur l'autre (zone IV); une zone complexe ~ d6formation rrmltiphas& (zone V); des structures d'extrusion tectonique (zone VI). Karl ~emyr (3oHa 3), ~Ba aa~lBnra qemyfi~aTl, tx C~CTeM apyr Ha ~pyra (3oHa 4) norc c inoro~a3oBofi ~eqbopia-~Hefi (3OHa 5) H ~iamq3om,ie cTpyKTypl, I (3oHa 6).

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SUMMARY Borehole breakouts and drilling‐induced tensile fractures (DITFs) were interpreted in 61 wells in the Cooper Basin indicating an average maximum horizontal stress orientation of 101°N. A total of 890 borehole breakouts and 608 DITFs were interpreted in the Cooper Basin. The approximately east–west maximum horizontal stress orientation is consistent over much of the basin, except in the Patchawarra Trough where maximum horizontal stress rotates to a northwest–southeast orientation. This rotation in maximum horizontal stress orientation is consistent with in situ stress data to the northwest of the Cooper Basin. The stress field in the Cooper Basin appears to mark the apex of a major horseshoe‐shaped rotation in maximum horizontal stress direction across central eastern Australia. Finite element modelling of the in situ stress field of the Indo–Australian Plate (IAP) using a range of plate‐scale tectonic forces is able to match the regional maximum horizontal stress orientation over most of Australia reasonably well, including the mean east–west maximum horizontal stress orientation in the Cooper Basin. However, plate boundary–scale modelling does not adequately match the horseshoe‐shaped stress rotation across central eastern Australia. The average east–west maximum horizontal stress orientation in the Cooper Basin indicates that stresses from tensional forces acting along the Tonga–Kermadec subduction zone are not transmitted into the interior of the Australian plate. The majority of the tensional forces associated with the Tonga–Kermadec subduction zone are most likely accommodated along the numerous spreading centres within the Lau–Havre backarc basin. A number of more localized stress anomalies have also been identified. These cannot be explained by plate‐scale tectonic forces and are possibly a result of geological structure and/or density contrasts locally perturbing the stress field.

10The Cenozoic tectonic evolution of Thailand is widely considered to have been primarily 11 controlled by forces generated at the eastern Himalayan syntaxis. This hypothesis is supported by 12 earthquakes in northern Indochina and southern China, which reveal a fan shaped present-day 13 maximum horizontal stress (S Hmax ) pattern centered on the eastern Himalayan syntaxis. However, 14 the distance to which forces generated by the Himalayan syntaxis influence the stress pattern in 15 Indochina is not known. We analyzed caliper and image logs from 106 petroleum wells for 16 borehole breakouts and drilling-induced fractures. A total of 558 breakouts and 45 drilling-17 induced fractures were interpreted in six basins, indicating that a north-south regional present- processes also influence the stress field in Thailand. We suggest that stresses generated by the 27 Sumatran-Andaman subduction zone may also have resulted in significant deformation in 28 offshore Thailand and that the stress pattern may also be perturbed at very local (several km) 29 scales by mechanically weak faults. 30 31