Question: what type of magma formed at mid-ocean ridges
[{'answer': 'basalt', 'provenance': [{'wikipedia_id': '1821971', 'title': 'Mid-ocean ridge', 'start_paragraph_id': 8, 'start_character': 479, 'end_paragraph_id': 8, 'end_character': 485, 'bleu_score': 1.0, 'section': 'Section::::Description.:Volcanism.\n'}]}, {'answer': 'gabbro', 'provenance': [{'wikipedia_id': '1821971', 'title': 'Mid-ocean ridge', 'start_paragraph_id': 8, 'start_character': 779, 'end_paragraph_id': 8, 'end_character': 785, 'bleu_score': 1.0, 'section': 'Section::::Description.:Volcanism.\n'}]}]