Question: where are the two major regions where dense water masses are created
[{'answer': 'North Atlantic', 'provenance': [{'wikipedia_id': '387457', 'title': 'Thermohaline circulation', 'start_paragraph_id': 1, 'start_character': 514, 'end_paragraph_id': 1, 'end_character': 528, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Southern Ocean', 'provenance': [{'wikipedia_id': '387457', 'title': 'Thermohaline circulation', 'start_paragraph_id': 1, 'start_character': 629, 'end_paragraph_id': 1, 'end_character': 643, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '387457', 'title': 'Thermohaline circulation', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 1146, 'bleu_score': 0.9894455409323081, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14500647454113419505}, 'section': 'Section::::Overview.:Formation of deep water masses.\n'}]}]