Gary Roberts set up all three goals for the pacesetters, laying on first-half efforts for Sam Morsy and Ollie Banks and a third for Eoin Doyle immediately after the break.
There was further good news for Chesterfield elsewhere as many of their nearest challengers dropped points, including second-placed Scunthorpe who were held to a goalless draw at Hartlepool.
Scunthorpe have now drawn four on the trot as they slip further adrift of the leaders.
Fleetwood, third at the start of the day, suffered a surprise 2-1 defeat at home to York for whom Wes Fletcher struck a last-gasp winner.
Conor McLaughlin's 45th-minute own goal had put York ahead only for Fleetwood to equaliser through substitute Mikael Mandron in the 72nd minute but the visitors claimed the spoils thanks to Fletcher.
Replacing Fleetwood in third were managerless Oxford, who were the only side in the top 10 aside from Chesterfield to record a League Two win this weekend after they defeated AFC Wimbledon 2-1.
Goals either side of half-time from Tom Newey and veteran striker David Connolly - who joined on loan from Portsmouth on deadline day - put Oxford in charge and they held on despite Charlie Wyke pulling a goal back 15 minutes from time.
Rochdale were beaten 1-0 at home by Dagenham, who recorded their first away win since October thanks to Rhys Murphy's close-range finish on 63 minutes.
Burton remain level-pegging with sixth-placed Dale on 47 points after drawing 1-1 at home with Exeter, Adam McGurk's ninth goal of the season quickly cancelling out an own goal by home skipper Ian Sharp in the 56th minute.
At the other end of the table, rock-bottom Northampton earned a 1-1 draw at Cheltenham under new manager Chris Wilder but they still find themselves further adrift at the basement following Torquay's win at Portsmouth.
Former Oxford boss Wilder could hardly have had a worse start to his reign when Jamie Cureton put Cheltenham ahead inside the opening minute but the Cobblers salvaged a point thanks to Matty Blair's second-half strike.
There was bad news elsewhere for Northampton though as second-bottom Torquay moved six points above them with 1-0 triumph at Pompey, Billy Bodin netting the winner in the 27th minute.
A first-half Anton Forrester goal helped Bury climb out of the bottom three with a 1-0 triumph over fellow strugglers Wycombe, while Plymouth salvaged a 1-1 draw from their home match with Mansfield as Lewis Alessandra's strike six minutes into injury-time cancelled out Matt Rhead's 74th-minute opener.
Saturday's other League Two match, Accrington's Lancashire derby at home to Morecambe, was abandoned after 56 minutes with the score 0-0 after heavy rain made some areas of the pitch unplayable.
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- Ollie Banks
- Sam Morsy