How should I introduce heavier elements on this world?

Based on this question I asked a while ago, I would like to know how to safely introduce new heavier elements to the world by asteroids without wiping the entire life and even keeps handy quantity of civilization to stay alive and prosper.

Assuming the quantity that would be delivered is roughly similar to our current available (refers to ground ores and processed ores we had by now), how could I safely deliver them to the surface via asteroid or asteroids (either a huge one or many smaller chunks)?

Requirements:

1. Maximum half the globe would be affected heavily by the bombardments
2. Its effects should be roughly similar to the meteor that hit earth 65 million years ago (though smaller effects would be preferred, consider it as the upper allowed limit)
3. The materials must be readily harvested, any that land on the sea might not be attainable given current technology
4. Please provide rough estimate of the asteroid(s) and its approximate intervals, given the event must be sufficiently alarming enough to the natives

Forethought:

• I thought of the possibility to have some smaller (considerably big though) meteors over short periods of time spreads over large land area.
• Also the possibility to have much more smaller meteors spreads over larger areas and larger timespan (days, weeks?), though I don't know whether it would be convenient.

Edit 1: narrowing the question's scopes.

posted over 9 years ago

Hendrik Lie‭

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