Geochemistry of volcanic glass from Mahanadi offshore region,eastern continental margin of India:Constraints on the contribution of latest Toba super-eruption  

作　　者：Muralidhar Kocherla Durbar Ray Manavalan Satyanarayanan Hilda Joao Virsen Gaikwad PB Ramamurty 

机构地区：[1]CSIR-National Institute of Oceanography,Dona Paula 403004,Goa,India [2]CSIR-National Geophysical Research Institute,Uppal Road,Hyderabad 500007,India

出　　处：《Acta Oceanologica Sinica》2024年第2期111-119,共9页海洋学报（英文版）

基　　金：We thank the Directors of CSIR-NIO and CSIR-NGRI,for supporting this study;This work is a part of a multidisciplinary program under the aegis of the National Gas Hydrate Program(NGHP),India,on gas hydrate exploration in the Eastern continental margin of India.The incharge of IPEV operations is thanked for providing onboard technical support and facilities.This research was funded by MoES,Govt.of India.Mr.Girish Prabhu and Mr.Vijay Khedekar are thanked for XRD and SEM analyses,respectively.This is NIO contribution no.7047.

摘　　要：The tephra layers in multiple sediment cores from the offshore region of the Mahanadi basin in the northern Bay of Bengal were investigated for possible volcanic sources. The glass shards from those tephra layers were studied for size distribution, texture, and elemental geochemistry to establish chronostratigraphic markers for regional and global Quaternary correlation. The textural features of fine-grained(silty) volcanic glasses suggest the distal source of these tephra deposits. Major element composition with elevated SiO_(2) contents ranging between75%–76% and dominance of K_(2)O(> 4.5%) over CaO(< 0.9%) suggest ashes have originated from siliceous rhyolitic melts, similar to the petrographic composition of tephra from the Toba volcano. The bulk trace element compositions of the same glass shards were comparable with those reported in the youngest Toba tephra reported elsewhere. Likewise, the LREE-dominated chondrite normalized REE profiles of tephra from the Mahanadi basin closely resemble the characteristic REE patterns in Toba ash from other parts of the Indian Ocean and thus confirmed the contribution of the youngest Toba super-eruption for this ash layers.

关 键 词：Mahanadi basin Bay of Bengal volcanic glass glass morphology glass-chemistry 

分 类 号：P736[天文地球—海洋地质] P317[天文地球—海洋科学]