Approach To A Comparison Between The Cenozoic Radiolarian Ooze And Its Older Analogues

Cenozoic radiolarian ooze depoited in equatorial ocean basins, siliceous rock deposited in palaeo-ocean basin which has vanished in orogenic belt, analogous and different between them. The depositional environment of modern radiolarian ooze is unique, the only conditions has to be met is the high productivity of the ocean surface. however, before Jurassic, foraminifer has not taken an advantage status in plankton species, siliceous sediments can be found in lots of faces, not only in ocean basin, but also around ocean islands, island arc system, the continental margin, continental shelf and even the shallow water environment. The samples refer to my dissertation are: 1.Cenozoic radiolarian ooze collected from East Pacific ocean bed; 2.Chert gathered from Paleo-Tethys Ocean.Testing these samples for element content with ICP-MS, analyzing and comparing the datas, we can finds:1. Cenozoic radiolarian ooze formed in the equatorial open ocean environment, less deposits, deposition rate is very low, and hiatus formed constantly because of bottom current erosion. PC7055 cores come from the East Pacific, with the length of 11.13m, contain the incomplete geology evolution history record from the Oligocene to now, MnO/TiO2,δCe and other indicators show that: the radiolarian ooze depoited in open ocean environment, have the MnO/TiO2>0.5 and significant negativeδCe anomalies (average 0.28), meanwhile Na2O/K2O show radiolarian ooze affected by volcanism.2. siliceous rocks from Paleo-Tethys refer to my paper, fromed in the deep-sea basins, oceanic islands, island arc, continental margin, deep-sea resedimentation and even shallow shelf and other tectonic - sedimentary environment. They are smiliar with radiolarian ooze that depoited in modern ocean in material composition, and also shows that extensively distribution of siliceous plankton shell, before the calcareous ooze a leading role in ocean sediments. Cherts from different tectonic-sedimentary faces have a obvious difference between the MnO/TiO2,δCe, Na2O/K2O. Because of the diagenesis, siliceous rock have different MnO/TiO2,δCe and Na2O/K2O value compared with Cenozoic radiolarian ooze, but have more common in MnO/TiO2, Na2O/K2O. Ce are sensitive to the chemical environment, and so we need to be careful when we use theδCe.3. The deposition and material composition of Siliceous rocks and siliceous ooze are relatively simple, sedimentary association and chemical element analysis are the basic tools to distinguish the sedimentary background geology evolutionary characteristic. Preliminary analysis shows that, MnO/TiO2, Na2O/K2O,δCe are important indicators to characteristicthe siliceous sediments.4. More operational and authoritative discriminant index for tectonic sedimentary environment of Siliceous rocks are still needed. The research system of Siliceous oozes especially the old siliceous rock need more work to do. The characteristic of Si isotope,O isotope and the inert gas isotope can provide more information, more energy and enthusiasm should be devoted.