b'Education matters structure of the lithosphere andThis thesis addresses several topicsoverturning the slab and producing slab sublithospheric upper mantle isrelated to the tectonic history of thetears. Model 2 interprets the anomaly created by jointly inverting availableSumatran-Andaman region. Firstly, Ias a westward dipping slab, required a seismic and non-seismic datasets. Theinvestigated the Martabe epithermalslablet derived from the Andaman Sea geochemical and geophysical modelsgold deposits using high-resolutionto have punctured the subducted Indian are then compared and jointly analysed40Ar/39Ar geochronology in orderplate. Model 1 fits within the tectonic to produce an integrated model ofto unravel the complex overprintingreconstructions published for this region lithospheric structure, the meltingalteration system. The results indicatebut requires a geodynamic mechanism to conditions and mantle processesthat there were five peak periods ofoverturn the slab, while Model 2 requires beneath the NVP. alunite growth around the Martabean unrecognised sutured subduction deposits at 1.40 to 1.70 Ma, 1.90 tozone within the Andaman Sea.Reuben Creighton, Australian2.08 Ma, 2.12 to 2.51 Ma and 3.22 and NationalUniversity: Using 3D3.48 Ma. Analysis of the Arrhenius plotsLastly, I report on a geomorphic analysis geodynamicslab models in tectonicput the closure temperature of aluniteaimed at assessing a different hypothesis reconstruction ranging between 390C and 519C, whichfor the evolution of the Sumatran Fault is above the temperature expected forSystem. Extensional structures in and In this thesis, two regions of convergentthe formation of the Martabe deposits.adjacent to restraining bends on the Cenozoic tectonics are investigated,This result gives confidence thatSumatran Fault System are unusual in and recent subduction is reconstructedthe measured ages from 40Ar/39Aran overall transpressive wrench regime. using 3D models that map the surfacegeochronology are for the formationIn addition, NW-SE trending tectonic of subducted slabs in the mantle. Inof alunite and not an age at which thelineaments appear to connect to offsets Iran, the subduction of the Neotethyssystem has cooled below the closureof the Sumatran Fault. Such features ocean prior to the collision of the Arabiantemperature. could be explained by westward rollback continent with Eurasia is reconstructed,of the hinge of the subducting Indian and the debates regarding the age ofSecondly, I created a 3D model of theplate driving NW-SE extension across continental collision, slab tearing, andsubducted slab beneath Sumatra andnorthern Sumatra. Slab-tearing may have the generation of adakitic magmatismthe Andaman Sea, and restored thelocalised rollback and created NW-SE are examined. From the magnitude ofmodelled slab geometry to the Earthstrending left-lateral strike-slip faults that reconstructed subducted lithosphere, asurface. This enabled recognition thatoffset the Sumatran Fault, eventually younger collision 28-27 Ma is favoured.the former spreading centres andrequiring the formation of new relay Tearing of the slab along the margintransform faults of the Wharton Fossilfaults to accommodate the ongoing occurs post-collision, initiating in theRidge localised a potential slab tear, thusrelative motion of the Sunda Block. The north-west at ~ 22 Ma and in central Irancircumventing otherwise enormousnew relay faults eliminate the obstacles at ~18 Ma. The second region of studydistortions that would have occurredcaused by offsets of the main fault strand. is the Pamir and Hindu Kush. Seismicduring subduction. SeismotectonicHowever, this model requires switching velocity anomalies and active deepanalysis suggests continuing movementbetween extended periods during which seismicity here have led to numerousduring subduction, in particular on thetransverse left-lateral strike-slip faults interpretations of the morphologytransform faults that once separated thedriven by differential slab rollback offset of the subducted lithosphere in thisspreading centres between the Indianthe Sumatran Fault, alternating with region. Two possible interpretations areand Australian plates. The emanation ofperiods during which there is a renewal modelled and evaluated with referencefluids from the deforming lithosphereof transpressional wrenching. Inferred to evidence from surface geology. Recentmay have localised both the Tobaswitches in the stress trajectories are extensional tectonics, evidenced bysupervolcano and the epithermal goldcomplementary to those documented in the exhumation of detachment fault- deposits at the Martabe. the Andaman Sea.bounded metamorphic domes, and geodetic evidence both favour a singleThirdly, tomography in the AndamanSuchir Patil, Australian National Eurasian slab rolling back, and producingregion is not characteristic of a simpleUniversity: Application of UAV coupled oroclinal bending in the Pamir. In thesubducting slab. Instead there arewith SfM-MVS to delineate the changing proposed model an extended basin onceunusual structures between 11N andlandscape of Lake Mungojoined the Tarim and Tadjik, floored by15N that have not been previously oceanic lithosphere. Subduction wasdiscussed. Tomographic anomalies canLake Mungo is a dry lake in the semi-triggered as it was overridden by thebe misleading and might be erasedarid environment of southeast Australia advancing Indian continent, around thewith improvements in tomographiclocated in southwestern New South time of the Oligocene-Miocene boundary.resolution. Nevertheless, we propose twoWales (NSW). It lies in the central portion Rapid rollback of the Pamir slab ahead ofinterpretations of the slab morphologyof the Willandra Lakes World Heritage the advancing Indian continent explainsthat explain a westward dip anomaly.Site. This region contains some of the current available evidence for extensionModel 1 consists of overturning theearliest evidence of Homo sapiens and exhumation during an episode ofsubducted Indian slab, a geometrysapiens outside Africa, establishing that large-scale collisional tectonics in thecommon for advancing hinges. However,humans had dispersed as far as Australia Miocene. an advancing Andaman trench is notby 42 000 years ago. Famous for its consistent with the relative motion of theoldest known cremation in the world Jack Muston, Australian NationalIndian plate. Instead, this morphologyand its significant archaeological traces, University: Volcanoes, ore deposits, andcould arise from the northward motionthe changing landscape in the recent the 3D slab geometry along the Andaman- of the Indian plate through the mantleyears has posed a threat to its heritage Sumatran subduction system rotating the edge of the Andaman slab,and history. Significant denudation in DECEMBER 2020 PREVIEW 34'