The origin of the Charcot Anomaly, Antarctic Peninsula, and implications for the tectonic evolution of the mid-Cretaceous Pacific Gondwana margin.
Understanding of Cretaceous plate motions, and closure of the global plate circuit, is hampered by the "Cretaceous Normal Superchron” (CNS) between 120 and 84 Ma, an interval of very stable geomagnetic field that produced no magnetic striping over the ocean floor. This coincided with eruption o...
| Main Authors: | , , , , , |
|---|---|
| Format: | Conference Object |
| Language: | unknown |
| Published: |
2013
|
| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/33234/ https://hdl.handle.net/10013/epic.41723 |
| Summary: | Understanding of Cretaceous plate motions, and closure of the global plate circuit, is hampered by the "Cretaceous Normal Superchron” (CNS) between 120 and 84 Ma, an interval of very stable geomagnetic field that produced no magnetic striping over the ocean floor. This coincided with eruption of several oceanic large igneous provinces (LIPs), huge outpourings of magma (> 100,000 km3) that created vast regions of volcanic and related rocks (Coffin and Eldholm, 1993), concentrated in time in what is called a superplume event, and associated with a global episode of plate reorganisation (Matthews et al., 2012). Lack of sea floor magnetic striping during the CNS has complicated the task of reconstructing plate motions in detail, leaving large uncertainties in the relative positions of continents, oceans, and the LIPs they bear. Perversely, prolonged stability of the geomagnetic field at these times means that sea floor magnetic striping, which is normally used to reconstruct plate motions, does not form when changes in plate motions can be at their greatest. 123 million years ago, one of the largest LIPs in Earth history was erupted in the palaeo-Pacific Ocean (Chandler et al., 2012; Taylor, 2006) at the beginning of the CNS, the 5 million km2 Ontong Java-Nui super-plateau (OJN; 2/3 the area of Australia). Shortly afterwards, as a result of the changes in palaeo- Pacific plate configuration associated with its formation, it is thought to have split into at least three component parts that are recognised today (e.g. Fig. 1) (Taylor, 2006), the Ontong-Java, Manihiki and Hikurangi plateaus (Fig. 1). 105 million years ago, still within the CNS, a global reorganisation of plate motions, associated with mountain building events on continental margins, was triggered by changes in subduction along the Gondwana margin in the vicinity of West Antarctica (Matthews et al., 2012). Matthews et al. (2012) presented two hypotheses for this to account for global plate reorganisation: 1) increased ridge crest–trench interaction at ... |
|---|