"merely caused" is correct and usable in written English.
You can use it to indicate that something happened but that it was not a significant cause of something else. For example, "The truck's late arrival merely caused a minor delay in the project."
Such independent explanations for beliefs can sometimes be correct, as in the case of someone given a post-hypnotic suggestion, in which case we may regard her judgment as merely caused and the reasons offered as mere rationalization.
The mortgage crisis hasn't merely caused millions of home foreclosures, cost big Wall Street firms tens of billions of dollars and forced layoffs.
Qaddafi's use of violence to defend himself merely caused the rebellion against him to spread — and provoked NATO to get involved — until, eventually, the uprising swallowed him.
The global recession sent the economies of rich countries into a tailspin, but merely caused the emerging economies to slow down a bit.
Whatever the explanation, the decline in deaths was not merely caused by the drop in driving as the Great Recession wore on.
No accidents have heppened with the device A Frenchman who tried to cause an accident by deliberately applying too much pressure merely caused the cork to fly out and a lot of wine with it, but the bottle was undamaged.
They say that the kind of mischief that today might merely cause delays and frustrations could eventually have more serious and far-reaching consequences.
However, it now seems to be the rule that merely causing sufficient offence on social media can be enough to get the perpetrator a jail term.
Such measures will merely cause further damage to Greece's already-stressed social fabric, rendering it incapable of providing the support that our reform agenda desperately needs.
In an often quoted statement published in Studio International in 1967 he wrote: "One merely causes things to reveal themselves to the sculptural awareness.
Barely enough of the drug was found for even a therapeutic dose, which merely causes patients to fall into light sedation.
