Does enchanting a land with an aura that gives it a triggered ability make that land no longer a mana ability?

A mana ability is defined in CR 605.1. To qualify, an ability must: (a) be an activated or triggered ability, (b) not be a loyalty ability, (c) when it resolves, it could produce mana, AND (d) it does not target. However, CR 605.1b specifically states that a triggered ability is a mana ability only if it triggers from another mana ability AND could itself produce mana.

So if you enchant a land with an Aura that grants it a triggered ability (for example, one that triggers whenever the land is tapped), that triggered ability is not a mana ability unless it both triggers off a mana ability AND could produce mana. A standalone triggered ability that just happens to produce mana does not meet the full criteria.

The land's own activated mana abilities (like a basic land's inherent tap ability) are completely unaffected by the Aura. Those abilities remain mana abilities under CR 605.1a regardless of what the Aura adds. The Aura doesn't alter existing abilities; it only adds new ones.

Concrete example: Suppose an Aura gives a Forest the triggered ability "Whenever this land becomes tapped, you may draw a card." That triggered ability is not a mana ability — it doesn't produce mana and doesn't trigger from a mana ability. The Forest's normal {T}: Add {G} is still a mana ability and is unaffected. Meanwhile, if an Aura granted "Whenever a mana ability of this land is activated, add {C}," that would be a triggered mana ability under CR 605.1b.

In summary: the land's existing activated mana abilities stay mana abilities. A new triggered ability added by an Aura is only a mana ability if it satisfies CR 605.1b (triggers from a mana ability and could produce mana). Most Aura-granted triggered abilities will not qualify as mana abilities.