The burning heart - The Proterozoic geology and geological evolution of the west Musgrave Region, central Australia

The Musgrave Province is one of the most geodynamically significant of Australia's Proterozoic orogenic belts, lying at the intersection of the continent's three cratonic elements - the West, North and South Australian Cratons. While remoteness and cultural sensitivity have slowed geological research into this region, recent collaborative programs in Western Australia (the west Musgrave Province) have done much to address this. This Focus Review provides a synthesis of this, and previous, work investigating the Mesoproterozoic to Neoproterozoic geological evolution of the province. The Musgrave Province is a Mesoproterozoic to Neoproterozoic belt dominated by granites formed and deformed during several major events. A cryptic juvenile basement is exposed mainly in the east Musgrave Province as c. 1600-1550. Ma orthogneiss and in the west Musgrave Province as isolated outcrops of granulite-facies metagranites of the c. 1575. Ma Warlawurru Supersuite. Zircon Hf-isotopic data suggest an earlier major juvenile crust-forming event at c. 1950-1900. Ma. There is, however, no evidence that the province evolved over Archean crust. The c. 1600-1550. Ma period probably involved evolution within a primitive arc setting, perhaps developed on c. 1950-1900. Ma oceanic or oceanic-arc crust. Voluminous calc-alkaline plutonism was accompanied by clastic and volcaniclastic basin formation during the 1345-1293. Ma Mount West Orogeny. This stage traced the evolution of a continental arc reflecting the final amalgamation of the combined North and West Australian Craton with the South Australian Craton. The intervening c. 1400. Ma primitive crust - the Madura Province - on which the proto-Musgrave Province had evolved, was consumed during amalgamation. The thickened crust resulting from this accretion was drastically thinned at the beginning of the c. 1220-1150. Ma Musgrave Orogeny as this central part of the new combined craton entered an extraordinary period of high heat flow characterised by c. 100. m.y. of ultrahigh-temperature metamorphism and high-temperature, anhydrous, alkali-calcic magmatism sourced from MASH chambers developed at the base of the thinned crust. The ridged cratonic architecture and a massive accumulation of high radiogenic heat producing granites within the mid crust perpetuated a thin crustal regime. Voluminous magmatism was again triggered during the c. 1090-1040. Ma Giles Event with the evolution of the magmatism-dominated, Ngaanyatjarra Rift. This event was likely initiated through renewed movement along translithospheric faults that intersected the thermally perturbed Musgrave Province, pinned at a cratonic junction. Mantle-derived bimodal magmatism extended more or less continuously for 50. m.y., producing one of the world's largest layered mafic intrusions and supervolcano-sized additions of juvenile felsic crust, in the form of alkali-calcic to alkali, A-type, rhyolite deposits. Together, the Albany-Fraser Orogen, which developed over the southern margin of the West Australian Craton, and the Musgrave Province mark the preserved edge of the North and West Australian Craton. These two belts show remarkable chronological links between c. 1345 and 1150. Ma but contrasting histories before and after that period. Their period of shared evolution reflects collision and accretion of the South Australian Craton, but their tectonic setting and basement geology throughout that event were very different

Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery

Background: Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery. Methods: A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury. Results: A total of 4164 patients were included, with a median age of 68 (i.q.r. 57\u201375) years (54\ub79 per cent men). Some 1153 (27\ub77 per cent) received NSAIDs on postoperative days 1\u20133, of whom 1061 (92\ub70 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4\ub76 versus 4\ub78 days; hazard ratio 1\ub704, 95 per cent c.i. 0\ub796 to 1\ub712; P = 0\ub7360). There were no significant differences in anastomotic leak rate (5\ub74 versus 4\ub76 per cent; P = 0\ub7349) or acute kidney injury (14\ub73 versus 13\ub78 per cent; P = 0\ub7666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35\ub73 versus 56\ub77 per cent; P < 0\ub7001). Conclusion: NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement