学術雑誌論文 Crustal formation and evolution processes in the Natal Valley and Mozambique Ridge, off South Africa

13pp.66 - 81 , 2017-09
ISSN:18739652
内容記述
The evolution of seafloor spreading of Africa, South America, and Antarctica is key to understanding the initial break-up of Gondwana. Vector geomagnetic surveys were conducted in the Natal Valley and Mozambique Ridge, off South Africa. We summarize the nature of the crust using the results of dense vector geomagnetic anomaly data, as well as satellite gravity data. Based on both inversion and forward analytical results, we identified areas of stretched continental crust, with basaltic magma intrusion in parts, as the northern Natal Valley, north part of the Mozambique Ridge, and north part of the southern Natal Valley. Oceanic crust was identified in the south part of the southern Natal Valley and south part of the Mozambique Ridge. Magnetic isochrons M0–M10 were identified in the south part of the southern Natal Valley. Clear magnetic lineations were observed in the south part of the Mozambique Ridge, where some areas were distorted by hotspot volcanism. The location of the continental ocean boundary in the Natal Valley, along with a four-stage model of tectonic evolution of the study area since about 183 Ma, are newly proposed.
本研究ではゴンドワナ大陸の初期分裂過程の詳細を理解するため、アフリカ沖ナタルバレーおよびモザンビークリッジで船上地磁気3成分観測を行った。地磁気異常データ解析の結果と衛星重力データ等を用い、この海域の地殻の起源を明らかにした。観測海域北側では、玄武岩の貫入を伴う引き伸ばされた大陸地殻の存在を明らかにした。観測海域の南西側では、新たに地磁気年代M0–M10(約120Ma–130Ma)とフラクチャーゾーンを同定した。また、観測海域の南東側では、海底拡大と同時のホットスポット活動が示唆された。これらの結果をもとに、この海域での新たな大陸および海洋地殻の分布を明らかにし、ゴンドワナ大陸初期分裂に関わる183Ma以降の新たな海洋底拡大史を提案した。

このアイテムのアクセス数:  回

その他の情報