Thurston Island (West Antarctica) between Gondwana subduction and continental separation: a multi-stage evolution revealed by apatite thermochronology

first_imgThe first low‐temperature thermochronological data from Thurston Island, West Antarctica, provide insights into the poorly constrained thermo‐tectonic evolution of the paleo‐Pacific margin of Gondwana since the Late Paleozoic. Here we present the first apatite fission track (AFT) and apatite (U‐Th‐Sm)/He (AHe) data from Carboniferous to mid‐Cretaceous (meta‐) igneous rocks from the Thurston Island area. Thermal history modeling of AFT dates of 145–92 Ma and AHe dates of 112–71 Ma, in combination with kinematic indicators, geological information and thermobarometrical measurements, indicate a complex thermal history with at least six episodes of cooling and reheating. Thermal history models are interpreted to reflect Late Paleozoic to Early Mesozoic tectonic uplift of pre‐Jurassic arc sequences, prior to the formation of an extensional Jurassic–Early Cretaceous back‐arc basin up to 4.5 km deep, which was deepened during intrusion and rapid exhumation of rocks of the Late Jurassic granite suite. Overall Early to mid‐Cretaceous exhumation and basin inversion coincided with an episode of intensive magmatism and crustal thickening and was followed by exhumation during formation of the Zealandia‐West Antarctica rift and continental break‐up. Final exhumation since the Oligocene was likely triggered by activity of the West Antarctic rift system and by glacial erosion.last_img read more

Biden signs immigration orders as Congress awaits more

first_imgWASHINGTON (AP) — President Joe Biden has signed a second spate of orders to undo his predecessor’s immigration policies, demonstrating the powers of the White House and its limitations without support from Congress. His orders on family separation, border security and legal immigration bring to nine the number of executive actions on immigration during his first two weeks in office. With proposed legislation to give legal status and a path to citizenship to all of the estimated 11 million people in the country who don’t have it, Biden has quickly taken aim at many of former President Donald Trump’s sweeping changes to deter immigration, both legal and illegal.last_img

Lloyd’s insurer Apollo to stop covering Adani’s Carmichael coal mine in September 2021

first_imgLloyd’s insurer Apollo to stop covering Adani’s Carmichael coal mine in September 2021 FacebookTwitterLinkedInEmailPrint分享Reuters:Lloyd’s of London firm Apollo has written insurance for Adani Enterprises’ Carmichael thermal coal mine which expires in Sept 2021 but is not planning to provide any further insurance for the mine, according to a memo seen by Reuters.Carmichael has provoked controversy in Australia because it would open up a new thermal coal basin at a time of growing concerns over global warming, in a region that is in need of jobs. Adani has begun construction at Carmichael, which will start by producing 10 million tonnes of coal per year together with an associated rail project, and expects first production in 2021.“We participate in one construction liability policy in respect of Adani Carmichael…this particular policy terminates in September 2021 after which we will no longer provide any insurance cover for this project,” chair of Apollo Syndicate Management Julian Cusack said in the memo.“We have recently declined to participate in an additional policy relating to the port and rail extension and have agreed that we will not participate in any further insurance policies for risks associated with this project.”Cusack confirmed to Reuters via LinkedIn that he had written the memo. Adani did not immediately respond to a request for comment.Lloyd’s of London, which has more than 90 syndicate members, does not have an overarching policy on coal, though the Stop Adani campaign says 17 Lloyd’s insurers have ruled out insuring the mine.[Carolyn Cohn]More: Lloyd’s insurer Apollo to stop underwriting Adani coal mine from September 2021last_img read more