The isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) and branched glycerol dialkyl glycerol tetraethers (brGDGTs) in marine sediments have been widely used for paleoceanographic reconstructions. However, their distributions in the deep ocean (> 4000 m) have not been well characterized. This study analyzed GDGTs in surface sediments from the seamount area of Marcus-Wake and Magellan, western Pacific Ocean (4431-5756 m). The results were further compared with published data of GDGTs in the South China Sea (SCS), equatorial Pacific Ocean, and Mariana Trench to reveal the provenance of GDGTs in the deep ocean and their suitability for paleoceanographic reconstruction. The ratios of GDGT-0/crenarchaeol (0.59–1.38) and GDGT-2/3 (10.65–14.78) indicate the contribution from benthic Thaumarchaeota in the seamount area. The isoGDGTs of the surface sediments from the seamount and the Mariana Trench regions were clustered for a redundancy analysis. They are characterized by the similar relative abundance of each isoGDGT, i.e. higher fractional abundance of GDGT-0 (26–49%) than those in the SCS (12–23%) and the equatorial Pacific Ocean (22–28%). This suggests isoGDGTs in the deep ocean (> 4000 m) are for both planktonic and benthic Thaumarchaeota and the benthic Thaumarchaeota likely produce excessive GDGT-0 in the seamount area. For brGDGTs, the higher IIIa/IIa ratios in the seamount area (1.67–4.83) than the marine-derived values (0.92), indicating in-situ production of brGDGTs. The discrepancy (0.7 to 5.0 °C) between sea surface temperature, deduced by TetraEther indeX (TEX₈₆), and the observed sea surface temperature is likely due to less input of isoGDGTs from the pelagic Thaumarchaeota but more from the benthic Thaumarchaeota.

海洋沉积物中的类异戊二烯甘油二烷基甘油四醚（isoGDGTs）和支链甘油二烷基甘油四醚（brGDGTs）已广泛用于古海洋学重建。然而，它们在深海（> 4000 m）中的分布尚未得到很好的表征。本研究分析了西太平洋 Marcus-Wake 和 Magellan 海山地区 (4431-5756 m) 表层沉积物中的 GDGT。将结果与已发表的南海 GDGTs 数据（ SCS)、赤道太平洋和马里亚纳海沟，以揭示深海 GDGT 的起源及其对古海洋重建的适用性。GDGT-0/crenarchaeol (0.59-1.38) 和 GDGT-2/3 (10.65-14.78) 的比率表明海山地区底栖生物的贡献。对来自海山和马里亚纳海沟地区的表层沉积物的 isoGDGT 进行聚类以进行冗余分析。它们的特点是每个 isoGDGT 的相对丰度相似，即 GDGT-0 的分数丰度 (26-49%) 高于SCS中的丰度(12–23%) 和赤道太平洋 (22–28%)。这表明深海（> 4000 m）中的isoGDGTs适用于浮游生物和底栖生物，而底栖生物可能在海山区域产生过量的GDGT-0。对于 brGDGT，海山区域的 IIIa/IIa 比率（1.67-4.83）高于海洋衍生值（0.92），表明 brGDGT 的原位生产。_{由 TetraEther indeX (TEX 86 )}推断的海面温度与观测到的海面温度之间的差异（0.7 至 5.0 °C）可能是由于来自远洋神秘生物的 isoGDGT 输入较少，但来自底栖神秘生物的输入较多。