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Computational ghost imaging (CGI) enables an image to be recorded using a single-pixel detector. The image can be reconstructed from correlations between the scene and a series of known projected intensity patterns. In this work we investigate the performance of CGI using pseudo non-diffracting (ND) speckle patterns. We demonstrate an extended depth-of-field that is ∼ 2-3 times greater than that achievable with conventional speckle, when only computing each intensity pattern to a single depth. In addition, the average speckle grain size of ND speckle is reduced by a factor of ∼ 1.5 relative to conventional speckle, which enhances the lateral Rayleigh-limit resolving power of our reconstructed images. However, the point-spread function (PSF) of our imaging system takes the form of a Bessel beam, which manifests itself as long-range correlations between speckle grains in the projected patterns. We discuss the trade-off between enhancement of the depth-of-field and the lateral resolution when using ND speckle, at the expense of a reduction in image contrast. Our work demonstrates that the tailoring of lateral and axial correlations in projected intensity patterns permits PSF engineering in CGI.

High-speed video stereo-microscopy relies on illumination from two distinct angles to create two views of a sample from different directions. The 3D trajectory of a microscopic object can then be reconstructed using parallax to combine 2D measurements of its position in each image. In this work, we evaluate the accuracy of 3D particle tracking using this technique, by extending the number of views from two to four directions. This allows us to record two independent sets of measurements of the 3D coordinates of tracked objects, and comparison of these enables measurement and minimisation of the tracking error in all dimensions. We demonstrate the method by tracking the motion of an optically trapped microsphere of 5 μm in diameter, and find an accuracy of 2-5 nm laterally, and 5-10 nm axially, representing a relative error of less than 2.5% of its range of motion in each dimension.

We demonstrate a new method for measuring the sedimentation of a single colloidal bead by using a combination of optical tweezers and a stereo microscope based on a spatial light modulator. We use optical tweezers to raise a micron-sized silica bead to a fixed height and then release it to observe its 3D motion while it sediments under gravity. This experimental procedure provides two independent measurements of bead diameter and a measure of Faxén's correction, where the motion changes due to presence of the boundary.

The Parapara Group of northwest Nelson is a faulted sequence of folded and metamorphosed Permian‐Triassic sedimentary rocks. Stratigraphically, from bottom to top, the sequence consists of: massive black Draco Slate (new term), at least 200 m thick; Flowers Formation, which consists of the Pupu Conglomerate Member (20 m thick), Cross Member (new term; 35 m thick), Tarn Sandstone Member (new term; 35 m thick), and Pariwhakaoho Slate Member (30 m thick); and Walker Formation (>200 m thick). Fossils in the Cross Member indicate a Middle Permian (Ufimian‐Kazanian) age and have long been recognised as having affinities with similar faunas in Tasmania and eastern Australia. Dropstones within the Draco Slate and Flowers Formation indicate glacial influence. The geochemical composition of sandstones suggests a dominant continental arc source for the Parapara Group sediments. Thin (

Ion microprobe dating of zircon and monazite from high-grade gneisses has been used to (1) determine the timing of metamorphism in the Western Province of New Zealand, and (2) constrain the age of the protoliths from which the metamorphic rocks were derived. The Western Province comprises Westland, where mainly upper crustal rocks are exposed, and Fiordland, where middle to lower crustal levels crop out. In Westland, the oldest recognisable metamorphic event occurred at 360-370 Ma, penecontemporaneously with intrusion of the mid-Palaeozoic Karamea Batholith (c. 375 Ma). Metamorphism took place under low-pressure/high-temperature conditions, resulting in upper-amphibolite sillimanite-grade metamorphism of Lower Palaeozoic pelites (Greenland Group). Orthogneisses of younger (Cretaceous) age formed during emplacement of the Rahu Suite granite intrusives (c. 110 Ma) and were derived from protoliths including Cretaceous Separation Point suite and Devonian Karamea suite granites. In Fiordland, high-grade paragneisses with Greenland Group zircon age patterns were metamorphosed (M1) to sillimanite grade at 360 Ma. Concomitant with crustal thickening and further granite emplacement, M1 mineral assemblages were overprinted by higher-pressure kyanite-grade metamorphism (M2) at 330 Ma. It remains unclear whether the M2 event in Fiordland was primarily due to tectonic burial, as suggested by regional recumbent isoclinal folding, or whether it was due to magmatic loading, in keeping with the significant volumes of granite magma intruded at higher structural levels in the formerly contiguous Westland region. Metamorphism in Fiordland accompanied and outlasted emplacement of the Western Fiordland Orthogneiss (WFO) at 110-125 Ma. The WFO equilibrated under granulite facies conditions, whereas cover rocks underwent more limited recrystallization except for high-strain shear zones where conditions of lower to middle amphibolite facies were met. The juxtaposition of Palaeozoic kyanite-grade rocks against Cretaceous WFO granulites resulted from late Mesozoic extensional deformation and development of metamorphic core complexes in the Western Province.

THE formation of the high-pressure, high-temperature rocks known as granulites has traditionally been attributed to metamorphism in the deeper parts of continental collision zones and magmatic arcs1-3. More recently, greater consideration has been given to the possibility of granulite formation during continental rifting4-6, and in particular4 to whether granulites are forming today beneath the North American Basin and Range province. Here we report thermobarometric data and single-zircon U-Pb ages for an analogous, but much more deeply exhumed, extensional terrain in Fiord-land, New Zealand7,8, where Early Cretaceous granulites underwent renewed granulite-facies metamorphism at significantly shallower crustal levels following the extensional collapse of magmatically thickened continental crust. Our data show that granulite-facies metamorphism can take place during continental extension, and demonstrate that in western New Zealand it was accompanied at higher structural levels by the emplacement of one or more metamorphic core complexes7-9, in keeping with the model postulated4 for the Basin and Range province.

We report what we believe to be the first use of a multilongitudinal-mode frequency-doubled microchip laser to pump a doubly resonant optical parametric oscillator (OPO). This compact OPO is based on potassium titanyl phosphate (KTP) and operates with a low pump power threshold of 35 mW. The OPO output consists of a single pair of signal and idler modes even though it is pumped with a multilongitudinal-mode pump laser. We achieved smooth tuning (1.7 GHz) of the output frequencies by temperature tuning of the pump laser.

[1] Low-pressure (P)–high-temperature (T) metamorphism previously attributed to crustal thickening accompanying nappe emplacement in the Paleoproterozoic Willyama Supergroup at Broken Hill is reinterpreted as a response to crustal extension (D1) and bimodal magmatism commencing circa 1700 Ma. D1 deformation occurred under amphibolite-granulite facies conditions, producing layer-parallel fabrics (S1) and metapelitic mineral assemblages in which andalusite dominated over sillimanite. Crustal extension ceased soon after 1640 Ma to be followed by crustal thickening, higher-pressure metamorphism, and northeast vergent recumbent folding (D2) attendant on inversion of the original D1 extensional structures. D2 recumbent folding has previously gone unrecognized but probably peaked around 1600 Ma before further amphibolite facies metamorphism between 1600 and 1590 Ma accompanying upright folding and northwest directed thrust faulting (D3). In the light of this revised tectonothermal history, geodynamic models erected to explain elevated thermal gradients and low-P–high-T granulite facies metamorphism in tectonically thickened crust may not be as relevant to Broken Hill as once thought. Above average crustal temperatures and low-P–high-T metamorphism in the Willyama Supergroup more likely occurred in response to voluminous magmatic intrusion accompanying crustal thinning, mantle upwelling and emplacement and unroofing of midcrustal rocks along a major detachment surface. A second major structural and/or stratigraphic break in the Willyama Supergroup is indicated by the absence of D1 fabrics from the uppermost part of the sequence.

Late Mesozoic continental extension combined with more recent transpression along the mid-Tertiary Alpine Fault have combined in Fiordland to uplift and expose unusually deep structural levels of a mid-Cretaceous metamorphic core complex. High pressure Early Cretaceous granulite facies orthogneisses occupy the axial region of this complex and were emplaced from deeper levels beneath a thinned and ductilely deformed cover sequence comprising mid- Palaeozoic granites, metasediments and metavolcanic rocks. Emplacement of the core complex was associated with widespread resetting of mineral isotopic systems in the (amphibolite facies) cover sequence whilst at higher crustal levels in the once- contiguous regions of Westland and Nelson crustal extension was accompanied by high-level silicic magmatism, normal faulting and nonmarine sedimentation in rapidly-subsiding fault-bounded asynmetric basins. Although the original boundary between the orthogneisses and cover sequence may have been intrusive, the present contact is a ductile shear zone in which the granulites have been rnylonitized and retrogressed to the amphibolite facies. Strongly lineated rnylonites in this zone developed before 93 Ma consistent with emplacement of the core complex during continental rifting and breakup of the Pacific margin of Gondwana, and prior to the onset of seafloor spreading in the Tasman Sea.

We report a continuous-wave, doubly resonant optical parametric oscillator (OPO) based on the nonlinear material periodically poled KTiOPO(4) and its application to spectroscopy. The OPO, which is pumped by a diode-pumped frequency-doubled Nd:YLF laser at 523 nm, has a low pump-power threshold of 25 mW and can deliver 10 mW of single-frequency output at 1.65 mum for a pump power of 200 mW. The idler wavelength can be temperature tuned at a rate of 0.73 nm/( degrees )C , and smooth tuning of the output frequency over ~3 GHz is achieved by smooth tuning of the pump laser. We demonstrate the practicality of the OPO by recording the absorption spectrum of methane near 1649 nm.

Detrital-zircon age spectra have been determined for sedimentary rocks from the Delamerian orogen, southern Australia. In Neoproterozoic sedimentary rocks, patterns progressively change from Mesoproterozoic- to Neoproterozoic-dominated detritus and there are few zircons that are close to the depositional age. The base of the Cambrian Kanmantoo Group marks an abrupt change in provenance to detrital patterns dominated by Ross and Delamerian (600–500 Ma) and Grenvillean ages (1200–1000 Ma). These patterns are strikingly similar to those obtained from Lachlan fold belt sedimentary rocks, indicating that the sedimentation recorded in the Kanmantoo Group marks a change from deposition of sediments derived from the Australian cratons to those representative of the early Paleozoic Gondwana mudpile. If sedimentary rocks with zircon-provenance characteristics such as those of the Kanmantoo rocks extend under elements of the Lachlan fold belt, they would provide suitable protoliths for the S-type granites of southeastern Australia.

Permian-Triassic strata from Parapara Peak in the Takaka terrane, western province, New Zealand, are dominated by detrital zircon peaks at ca. 240 Ma comparable to the Torlesse terrane of the eastern province. This contrasts with lower Paleozoic strata (Onekaka schist), which is comparable to other lower Paleozoic terranes (including adjacent Buller terrane) from the Gondwana margin that are characterized by detrital zircon patterns with characteristic peaks at ca. 500‐650 Ma and ca. 1000‐1150 Ma, a less distinct peak around 1400‐1700 Ma, and scattered Archean ages. These data indicate the close proximity of the eastern and western provinces by Permian time and a probable source region of Parapara Peak strata and Torlesse terrane in the New England fold belt of southeast Australia.

Ion-microprobe zircon U/Pb age data are presented for two metasedimentary sequences in Fiordland, New Zealand: one is a correlative of the Lachlan fold belt in southeast Australia and incorporates metamorphosed Ordovician turbidites intruded by 350–370 Ma S-type granites, and the other is equivalent in age to the older Delamerian fold belt and is derived from Cambrian-Ordovician protoliths (Kanmantoo Group) intruded by 480 Ma granitic orthogneiss. The latter was exhumed from lower crustal depths and is considered to be representative of basement not only in New Zealand but also in the formerly contiguous regions of southeast Australia and Antarctica. This basement underwent melting and low-pressure–high-temperature metamorphism at 350–370 Ma and yields detrital zircon with ages identical to those of inherited zircon in the mid-Paleozoic S-type granites.

The Delamerian orogen (southeast Australia) and the Wilson terrane (northern Victoria Land, Antarctica) constitute a formerly continuous lower Paleozoic fold-and-thrust belt developed along the paleo-Pacific margin of eastern Gondwana. Major folds and thrust faults in these regions, rooted in mid-crustal detachment zones, transported Cambrian-Ordovician granites and high-temperature- low-pressure metamorphic rocks divergently toward their respective western craton margins and eastern orogen margins and associated cover sequences. The structural imprints are related to the accretion of lower Paleozoic terranes at the eastern margin of the Delamerian orogen and the Wilson terrane. The continuity of the contemporaneous structure patterns in Australia and Antarctica is evidence for continuous convergent tectonism along the lower Paleozoic-Pacific margin of Gondwana.

Blueschists in southeastern Queensland, Australia, record a Carboniferous history of subduction and metamorphism at >6 kbar. A later thermal overprint associated with intrusion of S type granitoids ca. 306 Ma and regional greenschist facies metamorphism accompanied formation of ductile fabrics in the lower plate of an oceanic-protolith metamorphic core complex. Late Carboniferous extensional deformation in this part of the New England orogen may have accompanied outstepping of the subduction trench, or rollback and steepening of the paleo-Pacific plate during development of a wide zone of asthenospheric upwelling and continental back-arc extension. -Authors

The present configuration of Wilson Group, Bowers Supergroup and Robertson Bay Group in northern Victoria Land (Fig. 1) has been attributed to high-angle block-faulting1–3 or more recently4 to major strike-slip faulting along the Lanterman and Leap Year Fault zones. In this latter interpretation4, adjacent units have allochthonous relationships and constitute separate geological terranes. We offer additional support for the concept of allochthonous terranes in northern Victoria Land but suggest here an alternative model to explain terrane juxtapositions. Our model emphasizes the role of thrust tectonics and implies severe structural telescoping of entire terranes with significant loss of intervening crust. We further suggest that this occurred during the Lower Palaeozoic Ross Orogeny in response to the collision of Antarctica with a westwardly directed eastern continental block. This requires that the northern Victoria Land segment of Gondwana was a zone of major plate convergence throughout the Cambrian–early Ordovician period.

Margarite is both abundant and widespread throughout a sequence of interstratified amphibolite, hornblendite, and metamorphosed anorthosite from the upper Lyvia River, central Fiordland. These rock types comprise part of a metamorphosed layered intrusion. Assemblages recorded from these rocks are the product of two distinct phases of metamorphism. First generation assemblages typically comprise plagioclase (An84–96), hornblende, kyanite, and minor corundum. Clinozoisite and chlorite occur as late stage breakdown products of plagioclase and hornblende. Margarite developed during the second phase of metamorphism. Within the corundum-bearing rocks replacement of corundum or plagioclase by margarite can be observed directly. On the basis of these observations the following reaction is evident: 1 corundum+1 anorthite+1H2O=1 margarite. In other assemblages the formation of margarite can be attributed to the breakdown of kyanite and clinozoisite according to the reaction: 2 kyanite+2 clinozoisite=1 margarite+3 anorthite. Margarite is found, however, to contain appreciable amounts of paragonite solid-solution (up to 28 mol%) and plagioclase produced (second generation) is not pure anorthite but of intermediate compositions (An46–62). The reaction therefore involves the introduction of both soda and silica. Margarite also crystallized independently of clinozoisite according to a reaction of the general form: 5 pargasite+17 kyanite+19 H2O =8 margarite+4 chlorite+7 plagioclase. Application of available experimental data suggests that the margarite formed between 550 and 720 ° C up to a maximum pressure of 9.5 kb. Whereas the involvement of albite component (second generation plagioclase) will tend to lower the temperatures and pressures necessary for the occurrence of margarite, this effect is partially offset by the significant amounts of paragonite end-member held within the margarite. An independent estimate of the metamorphic conditions in metapelites suggests that the introduction of albite lowers equilibration temperatures by about 2 ° C for every 1% albite.

Using a combination of computer modelling and experimental observation we have studied the dynamic behaviour of a doubly-resonant optical parametric oscillator (OPO). When pumped above threshold, it is observed that a finite time is required for the output of the OPO to be established. Specifically, for a doubly-resonant OPO based on KTP with a cavity length of 11 mm, pumped at 523 nm and phase-matched to give near degenerate output, we observe a build-up time for the OPO output of the order of 1 μs. The observations are in excellent agreement with our numerical modelling and can be attributed completely to the time required for the OPO output to build-up from the parametric fluorescence.