English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

During Leg 27 basalt was recovered from three sites in the eastern Indian Ocean on the Perth, Argo, and Gascoyne abyssal plains. Basaltic basement of Upper Jurassic to Lower Cretaceous age was encountered at Sites 259 and 261. The upper part of the basement consists of highly altered basaltic breccia which grades downward into more compact and generally fresher rock. Relatively fresh specimens are quartz-normative tholeiites and olivine tholeiites, chemically similar to ocean ridge basalts; altered specimens are enriched in K2O and somewhat depleted in SiO and Na2θ. These are the oldest basalts known from the Indian Ocean, and they are believed to represent ancient oceanic crust formed during early rifting off Western Australia. Basalt sills were encountered at Site 260 and at the top of the basalt sequence at Site 261. At Site 260 the sill intrudes middle to lower Albian sediments and is probably much younger than basalt basement at adjacent sites. At Site 261 the sill has intruded at the base of the sedimentary sequence and its relative age is unknown. Both sills consist of relatively fresh quartznormative tholeiite characterized by very low K2O ( 12%) and by strong enrichment in REE relative to chondrites. This basalt probably represents intraplate activity at some time after formation of the basement.

Basalts from the Eastern Indian Ocean, DSDP Leg 27