1998年5月
Preservation of biogenic opal-A in earliest Cretaceous radiolarian claystone from the western Pacific
JOURNAL OF SEDIMENTARY RESEARCH
- ,
- 巻
- 68
- 号
- 3
- 開始ページ
- 435
- 終了ページ
- 439
- 記述言語
- 英語
- 掲載種別
- 出版者・発行元
- SEPM-SOC SEDIMENTARY GEOLOGY
Tuffaceous claystone with anomalously well-preserved radiolarian tests of Berriasian age was collected from the oceanward slope of the Mariana trench using the Japanese submersible Shinkai 6500. The rock is porous and light, slightly calcareous, and has experienced neither significant compaction nor deformation. Younger Cretaceous cherts are composed of recrystallized opal-CT and quartz silica phases, in which tests were destroyed, dissolved, and deformed. However, the oldest claystone still contains radiolarian tests of biogenic opal-A and dehydrated opal-A (opal-A'), showing slight dissolution,
This anomalous preservation of reactive biosilica required isolation from ordinary chemical and physical diagenetic conditions since deposition. The unusually weak diagenesis might occur from either avoidance of deep burial or unique chemical and physical microenvironments controlled by the clay-rich composition. The latter mould include the effect of high pore-fluid pressure due to low permeability, which may favor the anomalous preservation found in this rock.
This anomalous preservation of reactive biosilica required isolation from ordinary chemical and physical diagenetic conditions since deposition. The unusually weak diagenesis might occur from either avoidance of deep burial or unique chemical and physical microenvironments controlled by the clay-rich composition. The latter mould include the effect of high pore-fluid pressure due to low permeability, which may favor the anomalous preservation found in this rock.
- リンク情報
- ID情報
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- ISSN : 1527-1404
- eISSN : 1938-3681
- Web of Science ID : WOS:000073565100006