Tectonic reconstructions of the Cretaceous paleo-Pacific system show several significant tectonic and magmatic events, including the formation of several spreading centers, microplates and intra-oceanic arcs, and the initiation (>76–81 Ma) of magmatic activity which formed the Emperor-Hawaiian seamount chain. The Olyutorsky (syn. Achayvayam-Valaginsky, ~80 Ma) and Kronotsky (~90 Ma) intra-oceanic arcs were formed in the NW part of the paleo-Pacific and migrated northwest until their accretion onto the NW Asia margin in the Late Paleocene – Early Eocene and Late Eocene – Early Miocene, respectively. Tectonic remnants of these arcs are preserved as volcanic-sedimentary terranes in the accretionary basement of the Kamchatka Peninsula (Russia).

Fragments of the Olyutorsky terrane (OT) are exposed in Eastern Kamchatka, including (from south to north) in the Valaginsky Range (VR), Tumrok Range (TR), and Koryak Highlands (KH). The OT volcanic rocks are characterized by unusually primitive mafic-ultramafic compositions, with low- and high-K characteristics in the north (KH) and high-K in the south (VR and TR), respectively. The primitive compositions of these olivine-phyric (picrites) and basalts provides an opportunity to characterize the magmatic sources of intra-oceanic arcs during the Cretaceous.

High-Mg compositions in TR and VR (up to 40 wt% MgO) contain olivine phenocrysts with Fo content up to 94 mol% and high-Cr# spinel (up to 87 mol%), suggesting formation from an unevolved initial melt. Melt inclusions in spinel and olivine are Mg-rich (up to 15 wt% MgO) and have high K₂O contents (1.8–3.7 wt% for TR, and 2.3–3.9 wt% for VR). Picrite whole-rock compositions show strong HFSE depletion and LILE enrichment typical of modern arc rocks. However, LREE-Th enrichment is observed only in VR picrites, suggesting subduction-related modification is particularly strong in the source of magmas erupted in the southern OT. Isotopic compositions in OT picrites (⁸⁷Sr/⁸⁶Sr₈₀ 0.7026 to 0.7039, ε_Nd80 ± 10.6 to +8.4, ε_Hf80 + 20.6 to +16.7) resemble those in modern MORB (particularly Indian MORB) and arc picrites, suggesting that primitive OT arc magmatism originates in mantle wedge peridotite modified by melts and fluids derived from subducted oceanic crust without obvious contributions from continental and oceanic sediments. Compositional similarities between OT arc rocks and coeval early magmatism in the Emperor-Hawaiian melting anomaly suggests that the depleted component of the latter was an Indian-type MORB mantle in the paleo-Pacific region at the start of the Late Cretaceous.

Longitudinal variations in OT magmas compositions (e.g. high-K signature, subtly higher ⁸⁷Sr/⁸⁶Sr-²⁰⁶Pb/²⁰⁴Pb, and lower ε_Nd-ε_Hf in VR and TR) may be related to subduction of thicker and possibly older lithosphere in the southern segment of the Olyutorsky arc. Steeper dip angle and stronger deformation/flexure of the subducting plate below this part of the arc could drive the percolation of low-degree alkaline melts from the asthenosphere through the slab, resulting in generation of the “petit-spot” volcanoes, similar to those in the modern Japan Trench. Further subduction of such alkali-volcanoes may produce the high-K geochemical signature recorded in the southern OT arc terranes.

白垩纪古太平洋系统的构造重建显示了几个重要的构造和岩浆事件，包括几个扩张中心、微板块和洋内弧的形成，以及形成帝王的岩浆活动的开始（>76-81 Ma）。夏威夷海山链。Olyutorsky (syn. Achayvayam-Valaginsky, ~80 Ma) 和 Kronotsky (~90 Ma) 洋内弧形成于古太平洋的西北部分并向西北迁移，直到它们在晚古新世吸积到亚洲西北部边缘– 早始新世和晚始新世 – 早中新世，分别。这些弧的构造残余物在堪察加半岛（俄罗斯）的增生基底中作为火山沉积地体保存下来。

Olyutorsky 地体 (OT) 的碎片出露在堪察加东部，包括（从南到北）瓦拉金斯基山脉 (VR)、图姆洛克山脉 (TR) 和科里亚克高地 (KH)。OT 火山岩的特征是异常原始的基性-超镁铁质成分，北部（KH）分别具有低和高 K 特征，南部（VR 和 TR）分别具有高 K 特征。这些橄榄石质（苦橄榄岩）和玄武岩的原始成分为表征白垩纪洋内弧的岩浆来源提供了机会。

TR 和 VR 中的高镁成分（高达 40 wt% MgO）包含 Fo 含量高达 94 mol% 的橄榄石斑晶和高 Cr# 尖晶石（高达 87 mol%），表明由未演化的初始熔体形成。尖晶石和橄榄石中的熔体夹杂物富含镁（高达 15 wt% 的 MgO）并且具有高 K ₂ O 含量（TR 为 1.8-3.7 wt%，VR 为 2.3-3.9 wt%）。Picrite 全岩成分显示出现代弧岩典型的强烈 HFSE 耗竭和 LILE 富集。然而，LREE-Th 富集仅在 VR picrites 中观察到，表明与俯冲相关的修改在 OT 南部喷发的岩浆源中特别强烈。OT苦味酸盐中的同位素组成 ( ⁸⁷ Sr/ ⁸⁶ Sr ₈₀ 0.7026 至 0.7039, ε _Nd80 ± 10.6 to +8.4, ε _Hf80  + 20.6 to +16.7) 类似于现代MORB（特别是印度MORB）和弧形苦辉岩，表明原始OT弧岩浆作用起源于由俯冲洋壳衍生的熔体和流体改性的地幔楔橄榄岩，没有大陆和海洋沉积物的明显贡献。OT 弧岩与同时代早期岩浆活动在帝皇-夏威夷熔融异常中的成分相似性表明后者的耗尽成分是晚白垩世初期古太平洋地区的印度型 MORB 地幔。

OT 岩浆成分的纵向变化（例如高 K 特征、略高的⁸⁷ Sr/ ⁸⁶ Sr- ²⁰⁶ Pb/ ²⁰⁴ Pb 和较低的VR 和 TR 中的ε _Nd -ε _Hf）可能与较厚且可能较老的岩石圈的俯冲有关在Olyutorsky 弧的南段。这部分弧下俯冲板块的更陡倾角和更强的变形/弯曲可能会推动来自软流圈的低度碱性熔体通过板片渗透，导致“小点”火山的产生，类似于那些火山在现代日本海沟。这种碱性火山的进一步俯冲可能会产生记录在南部 OT 弧形地体中的高 K 地球化学特征。