(Adds environmental protester, Norway's Svindal withdrawing)
* Heavy fog forces delays in several mountain events
* Transgender Italian says held by police after protest
* Putin projects new, softer image at Games
* American pair skate for historic gold in ice dance
By Mike Collett-White
SOCHI, Russia, Feb 17 (Reuters) - Thick fog wreaked havoc with mountains events at the Winter Games on Monday, but the weather will be of no concern when Meryl Davis and Charlie White bid to become the first Americans to win the Olympic ice dance title later in the day.
After a week of uninterrupted sunshine, conditions have changed radically among the peaks of the Caucasus.
The men's biathlon 15km mass start event, already carried over from Sunday evening, was postponed again and will be held on Tuesday, while the men's snowboard cross competition was also moved to Tuesday.
Organisers are sensitive to safety concerns after a series of injuries at the Rosa Khutor Extreme Park over the weekend.
The worst accident involved Russian ski cross athlete Maria Komissarova, who underwent surgery for more than six hours on Saturday to attach a metal implant to her spine.
The 23-year-old was flown to a specialist clinic in Germany on Sunday where she will have a second operation, according to Russian Sports Minister Vitaly Mutko.
The injury was a rare piece of bad news at Russia's first Winter Olympics, where thrilling sporting action and state-of-the-art venues have impressed visitors and dispelled some of the doubts and criticism that marked the buildup to the Games.
President Vladimir Putin has been in the crowds at the Olympic Park on the Black Sea coast and up in the mountains, engaged in cosy chats with teams and Olympic officials and even turned up at Komissarova's bedside to offer support.
This is the "new" Putin on show. The pictures of him in action - riding horses bare-chested or shooting a tiger with a tranquiliser dart - have at least for now been carefully put to one side.
The Russia that Putin wants to portray at the Games is a caring country that has come a long way since the austere days of the Soviet Union. The leader he wants to portray is a man with whom the West can do business.
There has been little sign of protest, despite international outcry over Russian legislation banning homosexual propaganda among minors, and as yet Islamist militants opposed to Putin and the Games have not carried out their threats to attack Sochi.
In a rare display of dissent, a transgender former member of the Italian parliament, Vladimir Luxuria, held up a sign saying "Gay is OK" in Russian in the Olympic Park on Sunday.
She said she was detained by Russian police for about three hours and was told she could not display pro-gay slogans in public. Police declined immediate comment.
Critics of the law say it discriminates against gays and has fuelled violence against homosexuals.
International Olympic Committee spokesman Mark Adams said: "We hope that the Games will not be used as a platform for demonstrations."
Separately, a Russian man was detained in Sochi for demonstrating against the jailing of an environmentalist angered by the effects of huge Olympic construction projects.
A regional court last week rejected Yevgeny Vitishko's appeal against a three-year prison sentence on charges of damaging the regional governor's property, which he denies.
Vitishko's supporters say he is being punished for publicising environmental problems caused by the Olympics, and say the case was politically motivated.
On the 10th full day of sporting contest, the men's biathlon mass start and the snowboard cross competition were postponed until Tuesday, as the fog set in.
Norway's Aksel Lund Svindal was heading home without competing in his final two races at the Sochi Games after failing to win a medal, failing to live up to high expectations after he had shown great form so far this season.
And Olympic Nordic combined gold medallist Eric Frenzel of Germany is set to miss Tuesday's large hill event because of a virus, officials said.
Down in Sochi, excitement was building ahead of the free dance section of the ice dance competition at the Iceberg Skating Palace.
Davis and White raised the bar with Sunday's spectacular short dance display to a medley of songs from 'My Fair Lady', putting them in sight of Olympic history in one of the most popular events of any Winter Games.
The twice world champions are now one routine away from becoming only the fourth non-Russian couple to win the Olympic ice dance title.
"It felt awesome. When we were going out, we said, 'Let's do it for each other,'" said White. "We're letting it flow."
Host Russia goes for gold in the first bobsleigh medal of the Games at the Sanki Sliding Centre, where Alexander Zubkov set the pace at the halfway stage in the two-man event.
After China's women failed to turn their dominance of freestyle aerials into Olympic gold, it is the turn of the men with Liu Zhongqing and Qi Guangpu expected to fight it out with defending champion Alexei Grishin of Belarus for the title.
Unlike the last two Olympics, where Austria easily won the team ski jumping event, the competition looks likely to be a tightly contested affair.
Germany, Japan, Norway and Slovenia all pose a serious challenge and could leave the Austrians empty-handed. (Reporting by Reuters Olympic team in Sochi and Rosa Khutor; editing by Keith Weir/Peter Rutherford)