The phrase "a key chunk of" is correct and usable in written English.
It can be used to refer to an important or significant portion of something, often in discussions about information, data, or concepts.
Example: "In our analysis, a key chunk of the data revealed trends that we hadn't anticipated."
Alternatives: "an essential part of" or "a crucial segment of".
The main motion calls for a key chunk of the bill (part 2) be thrown out.
If it lost Britain, the EU would lose its historically most solid democracy, a major military power and a key chunk of its economic weight.
Queensland Nickel, which though presently a loss maker stands as a key chunk of Palmer's known fortune, will likely have to lay its cards on the table to have any prospect of the government helpfully pulling those levers.
A key chunk of Crowe's strategy fell into place with the $165 million acquisition in April of little software startup XCOM Technologies.
But they need to be able to do so on Apple's devices which make up a key chunk of the market.
After it went public, Google bought key chunks of its business, including YouTube and ad firm DoubleClick.
Key chunks of the NGWS platform will be hosted on the Internet, according to the company.
In all the excitement over new renewable and efficient energy solutions, we sometimes forget a key fact: a huge chunk of U.S. carbon emissions come from the transportation sector, and that sector is under monopoly control.
It's like pressing the delete key on a whole chunk of life.
The first room is a small white-wall gallery, from which one enters a cluttered closet, a filthy office bathroom, a dingy home bathroom, an office corridor, an abandoned off-track betting outfit... slightly off-key details accumulate: a chunk of ginger depends from a soap dispenser, for instance -.
Maybe that's why so many of his portraits of O'Keeffe -- they constitute a big chunk of the "key set" -- are so tiresome.
