Keywords
Equatorial Atlantic
spreading
transform fault
gravity anomalies
Section
Abstract
The morphology of lenticular transformed basins (LTB) in transform fault zones is examined, using the Romanche LTB as an example. Such systems are unique for the Global Ocean and reflect a complex combination of spreading and strike-slip processes of thin oceanic crust. The following morphostructural provinces are identified within the LTB: an accretionary massif province with a sealed passive trough valley, an active transform trough province, and northern and southern framing provinces. A morphostructural map has been compiled. The morphology of a series of marginal ridges located on the Northern Framing Ridge of the Romanche LTB is examined. These ridges formed in local transpression settings and are sensitive to changes in geodynamic regimes. It is hypothesized that they may be markers of regional geodynamic restructurings. An attempt is made to trace the formation and transformation history of the eastern marginal ridge. Two abrasion levels and a carbonate platform with a ring-reef structure indicate a complex, at least two-stage, uplift history of the Fillsbury Ridge.
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