The blockchain does not generate big data, it only acts as a storage or a ledger for the said data, but the algorithm of bitcoin, its transactions, addresses and whatnot is what produces all the data stored in the blockchain. The most important thing a blockchain can do is how it acts as a public ledger and also maintaining the credibility and integrity of the data stored within the chain. If the latter isn't followed or fulfilled by the former, there's no differentiating blockchain into any other public ledger systems.