LONDON (Reuters) – Hedge fund Elliott Associates and Jane Street Global Trading JSGT) are seeking to sue the London Metal Exchange (LME) for a combined $472 million after the LME cancelled nickel trades on March 8 when prices soared to top a record $100,000 a tonne. The nickel trading debacle is the biggest crisis to hit the world’s oldest metals forum in decades. The trades were cancelled because some LME members with short positions could not pay the margins – that cover losses in the event of member defaults – required by the exchange’s clearing house LME Clear. At one point on March 8 that…