当前位置: X-MOL 学术J. South Am. Earth Sci. › 论文详情
Ediacaran ophiolite relics in the SE Brazilian coast: Field, geochemical and geochronological evidence from metabasites and paragneisses
Journal of South American Earth Sciences ( IF 1.704 ) Pub Date : 2020-11-20 , DOI: 10.1016/j.jsames.2020.103040
Gabriel Godinho Capistrano; Renata da Silva Schmitt; Silvia Regina de Medeiros; Thayla Almeida Teixeira Vieira

Metabasites and paragneisses from the high-grade Ediacaran-Cambrian Cabo Frio Tectonic Domain, SE Brazilian coast, are investigated with field, geochronological (U-Pb combined with Lu-Hf), isotopic (Sm-Nd) and geochemical analyses. These units, tectonically interleaved with a Paleoproterozoic basement, record the pre-collisional setting within the eastern Ribeira Orogen. The four analyzed metabasite bodies indicate tholeiitic basalts/gabbros with OIB affinity as protoliths tending to high-Mg terms, also corroborated by their higher LILE, LREE and HFSE contents, in comparison to the E-MORB and N-MORB basalts. The Nb and Ta (Nb/Yb – alkaline proxy) and Ti/Yb (plume-melting proxy) resemble present-day OIBs values. One metabasite provided mainly metamorphic zircon crystals (n = 20) with a U-Pb age of 530 Ma. Only three crystals show oscillatory zoning, revealing ages of 1890 Ma, 676 Ma and 580 Ma. The Paleoproterozoic zircon, interpreted as a xenocryst, and the Epsilon Nd values (+3 and −6) for whole rock indicate crustal contamination. U-Pb data from detrital zircon of two paragneiss layers, structurally below and above the metabasite, constrain maximum depositional ages of 626 Ma and 549 Ma, respectively. The older has a major 750-620 Ma zircon source, similar to the age of Cryogenian magmatic units in the African terranes. The sediments of this layer are here interpreted as deposited in a distal continental passive margin, coeval with the OIB magmatism (metabasites) crystallized near or at the Ocean-Continent Transitional zone. The upper paragneiss layer shows a major juvenile Ediacaran detrital zircon source between 620 and 550 Ma, with mainly positive Epsilon Hf values (0 to +13). It also presents disrupted blocks of the metabasites, forming a sedimentary breccia. This latter evidence, in addition to its medium P-high T metamorphic paragenesis, supports the hypothesis of an accretionary prism system. The metabasites are here interpreted as ophiolite relics from an Ediacaran Ocean that predated the Gondwana amalgamation. The subsequent ca. 550-530 Ma continental collision preserved this tectonic sliver between the Paleoproterozoic continental crust, below, and the Ediacaran forearc sedimentary sequence, above (Palmital Succession). The formed Cambrian suture was later reactivated as one of the Cretaceous rift branches that evolved to the South Atlantic.

更新日期:2020-11-21
全部期刊列表>>
施普林格,自然编辑
ERIS期刊投稿
欢迎阅读创刊号
自然职场,为您触达千万科研人才
spring&清华大学出版社
城市可持续发展前沿研究专辑
Springer 纳米技术权威期刊征稿
全球视野覆盖
施普林格·自然新
chemistry
物理学研究前沿热点精选期刊推荐
自然职位线上招聘会
欢迎报名注册2020量子在线大会
化学领域亟待解决的问题
材料学研究精选新
GIANT
ACS ES&T Engineering
ACS ES&T Water
屿渡论文,编辑服务
ACS Publications填问卷
阿拉丁试剂right
林亮
南方科技大学
朱守非
华东师范大学
胡少伟
有机所林亮
隐藏1h前已浏览文章
课题组网站
新版X-MOL期刊搜索和高级搜索功能介绍
ACS材料视界
上海纽约大学
浙江大学
廖矿标
天合科研
x-mol收录
试剂库存
down
wechat
bug