The so-called Grey Glacier in the Torres del Paine National Park suffered the rupture earlier this week and authorities have warned that if it breaks into smaller fragments, it could become an obstacle for navigation routes.
Chile’s Conaf forestry service shared images of the enormous block of blue-white ice, which measured 350m (1,148ft) long by 380m (1,247ft) wide.
Park officials said ruptures like this are rare and had not occurred since the early 1990s.
Dr Ricardo Jaña, a glaciologist from the Chilean Antarctic Institute, said the iceberg was far larger than he had initially anticipated.
He said: “This is a situation we had anticipated, but the most singular and anecdotal thing is that it is an iceberg of much larger dimensions, which is notable.”
However he said the ice looks compact and consistent, meaning it is less likely to break up into smaller pieces.
The director of the National Forestry Corporation, Elizabeth Muñoz, said the situation is being monitored by satellites and a vessel, but did not give any further details.
The Grey Glacier is located in the Southern Patagonian ice field, just west of the Cordillera del Paine. Before dividing in two at its front end, the glacier is 6km wide and more than 30m high.
Torres del Paine is one of Chile’s largest an most popular national parks and welcomed more than 250,000 visitors last year.
It has also been named as the fifth most beautiful place in the world by National Geographic and the 8th Wonder of the World by TripAdvisor after a four-month contest in which people voted on 330 locations.
This is not the first significant fracture of a glacier during the year.
A one trillion tonne iceberg came off Antarctica recently and has been followed by scientists who seek to control the consequences of that fracture.