کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6433714 | 1636761 | 2014 | 13 صفحه PDF | دانلود رایگان |
- Anomalous seafloor mounds from the Natal Valley are described for the first time.
- The mounds represent macro-scale morphological features.
- These mounds are not caused by typical deep ocean basin processes.
- We suggest a link to the southward propagation of the East African Rift System.
The Natal Valley (southwest Indian Ocean) has a complicated and protracted opening history, as has the surrounding southwest Indian Ocean. Recently collected multibeam swath bathymetry and 3.5Â kHz seismic data from the Natal Valley reveal anomalous seafloor mounds in the northern Natal Valley. The significance, of these domes, as recorders of the geological history of the Natal Valley and SE African Margin has been overlooked with little attempt made to identify their origin, evolution or tectonic significance. This paper aims to describe these features from a morphological perspective and to use their occurrence as a means to better understand the geological and oceanographic evolution of this basin. The seafloor mounds are distinct in both shallow seismic and morphological character from the surrounding seafloor of the Natal Valley. Between 25Â km and 31Â km long, and 16Â km and 18Â km wide, these features rise some 400Â m above the sedimentary deposits that have filled in the Natal Valley. Such macro-scale features have not previously been described from the Natal Valley or from other passive margins globally. They are not the result of bottom water circulation, salt tectonics; rather, igneous activity is favoured as the origin for these anomalous seafloor features. We propose a hypothesis that the anomalous seafloor mounds observed in the Natal Valley are related to igneous activity associated with the EARS. The complicated opening history and antecedent geology, coupled with the southward propagation of the East African Rift System creates a unique setting where continental rift associated features have been developed in a marine setting.
Journal: Tectonophysics - Volume 630, 3 September 2014, Pages 300-312