Paleo-elevation and subsidence of ~145 Ma Shatsky Rise inferred from CO2 and H2O fresh volcanic glasses
Paleo-elevation and subsidence of ~145 Ma Shatsky Rise inferred from CO2 and H2O fresh volcanic glasses
复制标题
根据 CO2 和 H2O 新鲜火山玻璃推断 ~145 Ma Shatsky Rise 的古海拔和沉降
DOI：
10.1016/j.epsl.2013.09.023
复制
发表时间：
2013
影响因子：
5.3
通讯作者：
W.
中科院分区：
文献类型：
--
作者：
Shimizu;K.;Shimizu;N.;Sano;T.;Matsubara;N.;Sager;W.
沙茨基海隆是位于西北太平洋的一个大型中生代洋台，由三个海脊组成（Tamu、Ori和Shirshov），形成于洋中脊三联点附近。已发表的深度估计表明，沙茨基海隆并没有像典型的海洋岩石圈那样正常沉降。根据火山玻璃中溶解的CO2和H2 O以及综合大洋钻探计划324号考察队5个地点采集的岩芯描述，我们估计了沙特基海隆火山喷发的古喷发深度。Shatsky隆起的初始最大海拔估计为周围海底以上2500-3500米，Shatsky隆起随后的沉降估计为2600-3400米。我们没有观察到沙茨基隆起和翁通爪哇高原报告的异常低的沉降。虽然我们无法分辨沙茨基隆起是起源于热地幔柱还是非地幔柱的可熔地幔，但沙茨基隆起的升降历史都受到从塔穆地块中心（约2600 m）向奥里地块侧翼（约3400 m）沉降趋势的制约。在热地幔柱起源的情况下，沙茨基隆起可能形成于年轻的（1.5Ma）预先存在的洋壳上，地壳总厚度为1.20km。在这种情况下，沙茨基隆起的中心随后被后来的（长期的）地壳生长抬升，形成了观测到的30公里厚的地壳。对于非地幔柱的起源，沙茨基隆起可能已经形成在扩张脊中心作为最初的厚地壳（厚约30公里），后来减少沉降所造成的浮力质量的安置-也许是一个耐火地幔残留物-下的沙茨基隆起中心。
Abstract Shatsky Rise, a large Mesozoic oceanic plateau in the northwest Pacific, consists of three massifs (Tamu, Ori, and Shirshov) that formed near a mid-ocean-ridge triple junction. Published depth estimates imply that Shatsky Rise has not subsided normally, like typical oceanic lithosphere. We estimated paleo-eruption depths of Shatsky Rise massifs on the basis of dissolved CO 2 and H 2 O in volcanic glass and descriptions of cores recovered from five sites of Integrated Ocean Drilling Program Expedition 324. Initial maximum elevations of Shatsky Rise are estimated to be 2500–3500 m above the surrounding seafloor and the ensuing subsidence of Shatsky Rise is estimated to be 2600–3400 m. We did not observe the anomalously low subsidence that has been reported for both Shatsky Rise and the Ontong Java Plateau. Although we could not resolve whether Shatsky Rise originated from a hot mantle plume or non-plume fusible mantle, uplift and subsidence histories of Shatsky Rise for the both cases are constrained based on the subsidence trend from the center of Tamu Massif (∼ 2600 m) toward the flank of Ori Massif (∼ 3400 m). In the case of a hot mantle plume origin, Shatsky Rise may have formed on young (∼ 5 Ma) pre-existing oceanic crust with a total crustal thickness of∼ 20 km. For this scenario, the center of Shatsky Rise is subsequently uplifted by later (prolonged) crustal growth, forming the observed∼ 30 km thickness crust. For a non-plume origin, Shatsky Rise may have formed at the spreading ridge center as initially thick crust (∼ 30 km thickness), with later reduced subsidence caused by the emplacement of a buoyant mass—perhaps a refractory mantle residuum—beneath the center of Shatsky Rise.