* Carroll to remain in position until successor is appointed
* BHP's Vanselow, Xstrata's Davis in frame as replacements
* Shares rise over 4 percent on the news
By Clara Ferreira-Marques and Sinead Cruise
LONDON, Oct 26 (Reuters) - Anglo American's Chief Executive Cynthia Carroll has quit after more than five years in the job, under pressure from investors over the mining group's lagging share price and continued dependence on strike-hit South Africa.
A geologist by training, New Jersey-born Carroll ruffled feathers when she moved from the aluminium industry to become the first non-South African, the first woman and the first outsider to take the top job at Anglo in 2007.
Rejecting suggestions Carroll was pushed out, Chairman John Parker, her long-standing supporter, said there had been "differences of opinion" with shareholders but the decision to step down was Carroll's own, as she approached her seventh year in a "very gruelling and demanding role".
"Institutional pressure has been building for some time to replace Cynthia, so the news will be welcomed," one of Anglo's 15 largest shareholders said.
"Ultimately, running Anglo is one of the toughest jobs around and, although Cynthia made a good start as CEO, the feeling is the company has gone backwards in the last two to three years."
Carroll's efforts to streamline a mining group with colonial roots that became a sprawling conglomerate, her campaign to cut billions in costs and efforts to shift Anglo's centre of gravity away from South Africa have won her support among investors.
A campaign to improve ties with South Africa's government has also won praise - South Africa's mines minister, Susan Shabangu, said Carroll's departure was a "disappointment".
But Carroll's relationship with investors became troubled after big-ticket acquisitions such as the Minas Rio iron ore project in Brazil - an early bid to diversify Anglo's portfolio, which suffered cost overruns and delays.
Anglo has yet to give a final cost for Minas Rio, bought in a $5.5 billion deal at the top of the commodities cycle, but analysts say spending could rise to $8 billion from current forecasts of $5.8 billion, already twice original estimates.
"Her strategic moves didn't always hit the mark. The acquisition of Minas Rio, promptly followed by a dividend cut, was a particular low point," another of Anglo's 15 top investors said. Anglo scrapped its 2008 dividend to preserve cash.
Crippling strikes in platinum and iron ore mines in South Africa in recent weeks have revived long-standing worries over Anglo's exposure to the country, aggravating concerns about a share price that has underperformed its peers.
Despite her cost cuts, according to analysts at Macquarie, under Carroll Anglo has lost one-third of its value on a U.S. dollar market capitalisation basis and is now worth $25 billion less. Other major miners are worth at least the same as they were at the start of 2007.
Anglo's recent deals - including its decision to take control of diamond mining giant De Beers, raising its stake in Kumba Iron Ore and a July coal deal in Mozambique - have arguably done little to move away from a region that has held back its shares and, earlier this month, prompted an outlook downgrade from rating agency Standard & Poor's.
So far this year, Anglo stock has lagged the sector by almost 20 percent. Shares rose on news of Carroll's departure and at 1415 GMT were up 4.4 percent at 1939.5 pence, while the broader UK mining sector was up 0.8 percent..
The board did not immediately name a successor - a detail some analysts and industry sources took as a sign that the decision, though not unexpected, was to some degree unplanned. Parker told reporters there was no rush to pick a replacement for Carroll and that the 55-year-old would stay in place until a replacement was appointed, which could take months.
"For whoever comes in, the challenge of Minas Rio and the challenge of restructuring the platinum industry in South Africa doesn't go away," said analyst Des Kilalea at RBC in London. "To some extent, it's probably the most difficult mining company to manage at the moment."
Industry analysts, industry sources and investors point to at least two likely successors for Carroll - Brazilian Alex Vanselow, the former chief financial officer of BHP Billiton and South African-born Mick Davis, the outgoing chief executive of Xstrata.
Parker - in a reference to a storm over Davis' pay, one of the highest on Britain's FTSE - said Anglo could not afford him.
An internal replacement is less likely, but analysts point to Chris Griffith, a platinum veteran who was plucked from his job at the helm of Kumba in July to run Anglo American Platinum . His recent move, though, may rule him out.
A new name may not prove an immediate solution for Anglo's troubles, from cost pressures to Brazilian delays, even if the company could use the opportunity to review its involvement in South Africa as well as platinum, and sell a stake in the costly Minas Rio project or write down its value.
The biggest challenge is expected to be South Africa, where strikes have spread to Anglo American Platinum (Amplats), the world's top producer of the precious metal. The unrest has revived talk of a spin off of Amplats, in which Anglo currently owns an almost 80 percent stake - something Carroll has opposed.
Strikes have also hit Anglo's Kumba iron ore unit, which alone has accounted for almost half the miner's profit.
Kumba's Sishen mine has begun to ramp back up, but Amplats workers have not yet returned to the Rustenburg, Union and Amandelbult operations, which include some of its most labour intensive shafts, and those that have suffered deepest margin compression since 2008.
The group is expected to conclude a review of the platinum business by the end of the year.