Glacial isostatic adjustment (GIA) imparts geographic variability in the amplitude and timing of local sea-level (LSL) change arising from glacial-interglacial oscillations relative to a global mean signal (eustasy). We modeled how GIA manifests in the stratigraphic record across four shelf-perpendicular transects moving progressively more distal to the Quaternary North American ice complex, subject to varying amounts of GIA during glacial-interglacial cycles. Along each transect, we obtained LSL histories for nine sites between 1 m and 250 m water depth from the output of a gravitationally self-consistent GIA model run from marine oxygen isotope stage (MIS) 11 to the present. We paired each site's unique LSL history with 50 identical annual sedimentation models to create a library of 400-k.y.-duration synthetic stratigraphic columns (each assuming no tectonics). Comparison of the suite of synthetic stratigraphic columns between transects for a given bathymetric depth reveals latitudinal differences in the stratigraphically determined number, magnitude, and age of glacial-interglacial cycles, as inferred from stratigraphic sequence count, apparent water-depth change, and age of preserved deglacial transgression. We conclude that, for many field locales, extraction of primary information about the number, scale, and duration of pre-Cenozoic glacial-interglacial cycles from continental shelf stratigraphic records near ice sheets demands a deconvolution of the GIA signal.Continental shelf stratigraphic architectures are unparalleled archives of Phanerozoic Eon glacial oscillations (e.g., Miller et al., 2004, 2012; Isaacson et al., 2008; Rygel et al., 2008; Loi et al., 2010; Hoffman, 2011). However, tectonics, dynamic topography, and sedimentation can distort the preservation of depositional sequences, the apparent water-depth change of facies juxtapositions, and the number of erosional surfaces, which can lead to discrepant reconstructions of the number, magnitude, and relative age of inferred glacial cycles from continental shelf stratigraphy (Jervey, 1988; Einsele, 1993; Catuneanu et al., 2009). Many reconstructions of pre-Cenozoic glaciations that account for solid earth deformation and sedimentation presume that glacial oscillations impart uniform changes in accommodation and, therefore, identical stratigraphic architectures (Ghienne et al., 2014). Yet, a rich geophysical literature indicates that glacial isostatic adjustment (GIA), defined as the gravitational changes and viscoelastic deformation of Earth's crust due to the loading and unloading of ice sheets and oceans, generates spatially variable sea-level change and accommodation (Farrell and Clark, 1976; Milne and Mitrovica, 2008; Tamisiea and Mitrovica, 2011; Creveling et al., 2018).Thus, shelf stratigraphy during glacial epochs represents a combination of the relative rates of (1) local sea-level (LSL) change imparted by GIA, (2) sedimentation, and (3) solid earth deformation. In this study, we held factors 2 and 3 constant to focus on the extent to which factor 1 controlled the local stratigraphic expression of the number, scale, and age of “glacioeustatic” oscillations and, hence, obscured the along-strike correlation of glacial-interglacial depositional sequences.To explore the contribution of GIA to stratigraphic architectures, we developed a numerical model that creates computer-generated stratigraphic columns by combining LSL histories with identical model sedimentation histories under the assumption of no tectonic deformation. LSL histories refer to time series of local sea level, relative to the present, that capture spatial variability in GIA.We computed the marine oxygen isotope stage (MIS) 11 to present-day (400 k.y.) LSL histories for nine bathymetric depth sites—from 1 to 250 m depth—along each of four shelf-perpendicular transects spanning the Pacific coast of North America, a region variably impacted by GIA during Quaternary glacial-interglacial cycles (Figs. 1A–1C; Fig. S1 in the Supplemental Material1). These LSL predictions were generated from a gravitationally self-consistent sea-level theory (Kendall et al., 2005) that adopted the global ice-load history of Raymo and Mitrovica (2012) and the best-fitting regional one-dimensional (1-D) viscosity structure inferred by Creveling et al. (2017) for MIS 5 sea-level indicators. The model included an elastic lithosphere thickness of 95 km and uniform upper- and lower-mantle viscosities of 1020 Pa·s and 5 × 1021 Pa·s, respectively. The LSL histories represent model estimates of local accommodation change, i.e., the change in sea surface versus radial surface of the crust due to GIA (Mitrovica and Milne, 2003) at 1 k.y. time steps, which we linearly interpolated to annual resolution. Sediment loading (Dalca et al., 2013) and compaction (Ferrier et al., 2017) were not incorporated.We paired each of the 36 LSL histories (i.e., nine sites along four transects; Fig. S1) with the same 50 sedimentation histories. Each history drew annual depositional and erosional events (n = 400,000) from a truncated double-Pareto probability distribution function (PDF; Fig. 1D) for Cenozoic siliciclastic shelf sedimentation, with a mean of 30 ± 4 cm/k.y. (1σ; Trampush and Hajek, 2017). Model accumulation was comparable to late Pleistocene cores from Integrated Ocean Drilling Program (IODP) shelf sites within the area (Lyle et al., 2000; Akiba et al., 2009).The numerical model generated synthetic stratigraphic columns on top of an initial bathymetry (set to modern) by tabulating 400 k.y. sediment accumulation at each site assuming no lithification (Fig. 2). For every model year, local accommodation, or the modeled water depth, dictated sediment accumulation (Fig. 2A; Jervey, 1988). Sediment accumulated, or eroded, when positive accommodation exceeded the thickness of an annual depositional or erosional sedimentation event (Fig. 2B). When a depositional event filled accommodation, any remainder of the event was discarded (Fig. 2C). Forced regression induced erosion to the elevation of the LSL lowstand (Fig. 2D). If subsequent LSL rise generated positive accommodation again, then the process was repeated (Fig. 2E). To facilitate the correlation of synthetic stratigraphies within individual transects, and laterally between transects, the model identified subaerial unconformities (SUs; where forced regression resulted in subaerial exposure), correlative conformities (CCs; where forced regression did not result in subaerial exposure), and maximum flooding surfaces (MFSs; where maximum accommodation occurred between two SUs or their CCs; Fig. 2F; Johnson and Murphy, 1984; Van Wagoner et al., 1987, 1988; Galloway, 1989; Hunt and Tucker, 1992; Posamentier and Allen, 1999). Only the preserved depositional events and surfaces were stacked into synthetic stratigraphic columns (Fig. 2G).To quantitatively compare records, for each column, the model computed (1) a count of genetic stratigraphic sequences (GSSs), consisting of transgressive-regressive systems tracts (Fig. 2G; Galloway, 1989); (2) the difference in water depth between the oldest and youngest depositional event within each systems tract (Fig. 2G); and (3) the year of transgression after a SU within a given transect. By excluding physical processes such as loading, compaction, and lithification, and by asserting identical sedimentation histories and an initial topography, we did not seek to predict the real lithostratigraphy at these sites, but rather isolate the systematic effects of GIA on a local stratigraphic architecture. Incorporating local estimates for these features would enhance the geographic complexity imparted by GIA.During glaciations, the imposed LSL history differed both within individual transects (Fig. S1) and between transects down the coastline (Fig. 1C). The loading of a growing ice sheet caused a depression of the underlying crust, displacing mantle material laterally to create a peripheral bulge (Fig. 1B; Farrell and Clark, 1976). Across a deglaciation phase, the subsequent melting of the ice sheet led to (1) postglacial rebound of the crustal depression and subsidence of the peripheral bulge, resulting in LSL rise, and (2) gravitational effects that caused water to migrate away from the ice sheet, culminating in LSL fall. Because factor 1 tended to dominate over factor 2, and the magnitude of both effects dropped with distance from the ice load, the net result was that deglacial LSL rise decreased southward across the subsiding outer flank of the peripheral bulge (i.e., transects 2–4 [T2–4]). Additionally, the trend flattened out by the latitude of T3, so the LSL predictions for T3–4 showed reduced variability (Fig. 1C).T1 was located close to the edge of the ice load at maximum extent, and a large drop in LSL associated with gravitational effects combined with a more moderate crustal displacement across the deglaciation phase to culminate in a muted LSL change relative to T2–4. The proximity of T1 to the ice load introduced large shore-perpendicular gradients in the predicted sea-level signal (Fig. S1A). In contrast, peripheral bulge and gravitational effects at transects further south tended to have significantly smaller shore-perpendicular gradients, although ocean loading effects (Nakada and Lambeck, 1989; Mitrovica and Milne, 2003) may have contributed to these gradients (Figs. S1B–S1D).Figure 3 illustrates a selection of the sequence-stratigraphic and lithostratigraphic architectures that arose from the pairing of MIS 11 to present-day LSL histories with one random, but representative, sedimentation history. From each depth-site library (n = 50), a comparison of synthetic stratigraphic columns within individual transects revealed that, as bathymetric accommodation increased downdip toward the basin, so too did overall stratigraphic thickness, the number of preserved GSSs (Figs. 3A and 3B), and the water-depth change within a regressive system tract (Figs. 3C and 3D).A comparison of intermediate-depth (100–200 m) synthetic stratigraphic columns between transects (along depositional strike) exposed significant differences in these factors with a consistent geographic pattern (Figs. 3A and 3D). For example, T1 consistently preserved the longest columns with the highest count of GSSs (e.g., four sequences at 130 m depth), which pinched out at T2 to two sequences and expanded again toward T3–4 to approximately three sequences (Fig. 3A). For all sedimentation scenarios, the difference in mean count of GSSs between transects was highest and statistically significant (p < 0.05) for the 130–200 m depth sites (Fig. 3B; Table S1). Similarly, between transects, the apparent change in water depth within a GSS varied widely (Fig. 3C); for example, T2 recorded the largest local change in water depth leading into the Last Glacial Maximum (LGM) lowstand for sites 200 m and deeper and, thus, the largest apparent magnitude of ice-volume growth (Figs. 3C and 3D; Table S2). However, these geographic patterns in the number and magnitude of glacial cycles did not hold true for the 1–50 m and 250 m depth sites, as these columns were more statistically similar to each other (Figs. 3B and 3C), due to the limited and unlimited bathymetric accommodation, respectively, relative to the magnitudes of LSL variations (Fig. 1C).Figure 4 presents actual age distributions for the year of preserved transgressive deposition atop the local MIS 2 (LGM) lowstand SU or CC at selected depth sites. Model runs revealed up to a 5 k.y., or 1/24 of the most recent glacial-interglacial cycle, updip diachroneity as sea-level rise reached progressively shallower depth sites (Fig. 4, same color distribution across depth sites). Across-shelf diachroneity was more pronounced (Fig. 4, different color distributions for the same depth site). For example, across the 130 m depth sites, local transgression at T4 resumed ~8 k.y., or 1/15 of the cycle, earlier than at T1 (16.89 ka ± 4.41 k.y. [1σ] vs. 8.95 ka ± 7 k.y., respectively). Wherever diachroneity existed for MIS 10, 8, and 6 transgressive surfaces, the local expression of a given surface could appear up to ~150 k.y., or >1 cycle, earlier at T1 (Fig. S2).If glacioeustasy were a global signal, and tectonics and sedimentation were everywhere identical, then stratigraphic columns between transects at the same bathymetric depths would be indistinguishable and retain the same information about sea-level and ice-volume change. Instead, intermediate-depth sites on the continental shelf displayed the largest departures from one another. This is a direct reflection of the contribution of GIA to the preservation and character of glacial-interglacial stratigraphic cycles produced by this forward model.The library of stratigraphic records at the most ice-proximal intermediate site, T1 at 130 m depth, consistently preserved the highest number of glacial cycles, the earliest ages for deglaciations (save for LGM), and, as expected from the LSL curve (Fig. 1C), the smallest magnitude of LSL change. In contrast, T2 at 130 m depth, located on the outer flank of the peripheral bulge, recorded the least number of glacial cycles, and the magnitude of LSL change leading into the LGM was obscured by erosion (Figs. 3C and 3D). The intermediate-depth sites better revealed the retrogradation and progradation of lithofacies in response to GIA-induced LSL change at individual transects. However, even when sedimentation and tectonics were held identical across the coastline, GIA caused locations between transects to preserve a different number of glacial-interglacial cycles, apparent magnitude of LSL lowstand, and age of preserved transgressive deposition after a SU/CC in the stratigraphic record.These model experiments reveal that GIA can complicate the along-strike correlation of continental shelf stratigraphic records across 102–103 km distances (T1–T2), and farther (T3–T4; Figs. 3A and 3D). Depending on the preserved field margin relative to the contemporaneous ice margin, a stratigrapher may conclude conflicting information about the same glacial epoch.GIA creates geographically variable LSL change through glacial-interglacial cycles. In this study, we demonstrated how GIA-induced changes in LSL and accommodation alter the preservation of glacial-interglacial GSSs in continental shelf stratigraphic records. When tectonics, sedimentation, and bathymetric depths are identical, synthetic stratigraphic columns between transects display different information about the number, magnitude, and timing of ice-volume change. As a result, accurate correlation of continental shelf synthetic stratigraphic columns over several glacial oscillations is most difficult between sites proximal to the former ice sheet (T1) and those on the outer flank of the peripheral bulge, though closest to the bulge crest (T2). The accurate correlation of columns trending southward across the more distant sections of the outer flank of the peripheral bulge (T3 and T4) is easier. The range in bathymetric depths over which this pattern is observed will shift depending on initial bathymetry, sediment accumulation rates, and LSL histories. Improved understanding of the signal of GIA in continental stratigraphic records can refine reconstructions of the number, magnitude, and age of glaciations inferred from this physical archive.This research was made possible by U.S. National Science Foundation award 2046244, a Geological Society of America (GSA) graduate student research grant, and the Oregon State University George and Danielle Sharp Fellowship. We thank J.X. Mitrovica for LSL histories and thoughtful discussion, and Steven Holland and two anonymous reviewers whose comments improved this paper.

中文翻译：

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冰川均衡调整对大陆架地层对比的影响

冰川均衡调整 (GIA) 赋予了相对于全球平均信号 (eustasy) 的冰川间冰期振荡引起的局部海平面 (LSL) 变化幅度和时间的地理变异性。我们模拟了 GIA 如何在地层记录中体现在四个架子垂直样带上，这些断面逐渐远离第四纪北美冰复合体，在冰期-间冰期周期中受到不同数量的 GIA 影响。沿着每个样带，我们从海洋氧同位素阶段 (MIS) 11 到现在运行的重力自洽 GIA 模型的输出中获得了 1 m 和 250 m 水深之间的 9 个地点的 LSL 历史。我们将每个站点独特的 LSL 历史与 50 个相同的年度沉积模型配对，以创建一个包含 400-ky 的库 -duration 合成地层柱（每个都假设没有构造）。比较给定测深深度的横断面之间的合成地层柱套件揭示了地层确定的冰间冰期旋回的数量、幅度和年龄的纬度差异，从地层序列计数、表观水深变化和年龄推断保存下来的冰川海侵。我们得出结论，对于许多现场环境，从冰盖附近的大陆架地层记录中提取有关新生代前冰期-间冰期循环的数量、规模和持续时间的主要信息需要对 GIA 信号进行反卷积。无与伦比的显生宙冰川振荡档案（例如，Miller et al., 2004, 2012; Isaacson et al., 2008; Rygel 等人，2008 年；Loi 等人，2010 年；霍夫曼，2011）。然而，构造、动态地形和沉积作用会扭曲沉积层序的保存、并列相的明显水深变化以及侵蚀面的数量，这可能导致重建的数量、幅度和相对年龄存在差异。从大陆架地层学推断的冰川周期（Jervey，1988；Einsele，1993；Catuneanu 等，2009）。许多解释了固体地球变形和沉积的前新生代冰川作用的重建假设冰川振荡会产生均匀的适应变化，因此会产生相同的地层结构（Ghienne 等人，2014 年）。然而，丰富的地球物理文献表明，冰川均衡调整（GIA），定义为由于冰盖和海洋的加载和卸载导致地壳的重力变化和粘弹性变形，产生空间可变的海平面变化和调节（Farrell 和 Clark，1976；Milne 和 Mitrovica，2008；Tamisiea 和 Mitrovica，2011 ；Creveling 等人，2018 年）。因此，冰川时期的陆架地层学代表了 (1) GIA 赋予的局部海平面 (LSL) 变化、(2) 沉积和 (3) 固体地球的相对速率的组合形变。在这项研究中，我们将因子 2 和 3 保持不变，以关注因子 1 在多大程度上控制了“冰川运动”振荡的数量、规模和年龄的局部地层表达，从而掩盖了冰川沿走向的相关性。 -间冰期沉积序列。为了探索 GIA 对地层结构的贡献，我们开发了一个数值模型，该模型在假设没有构造变形的情况下，通过将 LSL 历史与相同的模型沉积历史相结合来创建计算机生成的地层柱。LSL 历史是指相对于现在的当地海平面的时间序列，它捕捉了 GIA 中的空间变异性。我们计算了九个测深深度站点的海洋氧同位素阶段 (MIS) 11 到今天 (400 ky) 的 LSL 历史——从 1 到 250 m 深度——沿着横跨北美太平洋沿岸的四个大陆架垂直样带中的每一个，该区域在第四纪冰期-间冰期周期中受到 GIA 的不同影响（图 1A-1C；补充材料中的图 S1） . 这些 LSL 预测是根据重力自洽海平面理论 (Kendall et al., 2005) 生成的，该理论采用 Raymo 和 Mitrovica (2012) 的全球冰负荷历史和最适合的区域一维 (1- D）Creveling 等人推断的粘度结构。(2017) 用于 MIS 5 海平面指标。该模型包括 95 km 的弹性岩石圈厚度和 1020 Pa·s 和 5 × 1021 Pa·s 的均匀上、下地幔粘度。LSL 历史代表了局部适应变化的模型估计，即由于 GIA（Mitrovica 和 Milne，2003）在 1 ky 时间步长下海面相对于地壳径向表面的变化，我们将其线性插值到年度分辨率。沉积物加载 (Dalca et al., 2013) 和压实 (Ferrier et al., 2017) 未纳入。我们将 36 个 LSL 历史中的每一个（即沿四个样带的 9 个地点；图 S1）与相同的 50 个沉积历史配对。每个历史都从新生代硅质碎屑陆架沉积的截断双帕累托概率分布函数（PDF；图 1D）中得出年度沉积和侵蚀事件（n = 400,000），平均值为 30 ± 4 cm/ky（1σ；Trampush 和哈耶克，2017）。模型积累与该地区综合海洋钻探计划 (IODP) 陆架站点的晚更新世岩心相当（Lyle 等人，2000；Akiba 等人，2009）。数值模型在初始测深顶部生成合成地层柱（设置为现代）通过在假设没有石化的情况下将每个地点的 400 ky 沉积物积累制表（图 2）。对于每个模型年份、当地住宿条件或模型水深，决定了沉积物的积累（图 2A；Jervey，1988）。当正适应超过年度沉积或侵蚀沉积事件的厚度时，沉积物积累或侵蚀（图 2B）。当沉积事件填满住宿时，该事件的任何剩余部分都被丢弃（图 2C）。强制回归导致对 LSL 低位海拔高度的侵蚀（图 2D）。如果随后的 LSL 上升再次产生正调节，则重复该过程（图 2E）。为了促进单个样带内和样带之间横向合成地层的相关性，该模型确定了地面不整合面（SU；强制回归导致地面暴露）、相关整合（CC；强制回归未导致地面暴露）和最大泛滥表面（MFS；两个 SU 或它们的 CC 之间发生最大调整；图2F；约翰逊和墨菲，1984；范瓦格纳等人，1987 年，1988 年；加洛韦，1989；亨特和塔克，1992；Posamentier 和艾伦，1999）。只有保存下来的沉积事件和表面被堆叠成合成地层柱（图 2G）。为了定量比较记录，对于每一柱，模型计算（1）成因地层序列（GSS）的计数，由海进-海退系统组成大片（图 2G；加洛韦，1989 年）；(2) 各系统域内最古老和最年轻沉积事件的水深差异（图2G）；(3) 在给定横断面内的 SU 之后的海侵年份。通过排除加载、压实和石化等物理过程，通过断言相同的沉积历史和初始地形，我们并没有试图预测这些地点的真实岩石地层，而是隔离 GIA 对当地地层结构的系统影响。结合对这些特征的当地估计将增强 GIA 赋予的地理复杂性。在冰川作用期间，施加的 LSL 历史在单个横断面（图 S1）和沿海岸线的横断面之间（图 1C）都不同。不断增长的冰盖的加载导致下伏地壳的凹陷，横向移动地幔物质以产生外围凸起（图1B；Farrell和Clark，1976）。在冰消期，随后冰盖的融化导致（1）地壳凹陷的冰后反弹和外围隆起的沉降，导致 LSL 上升，(2) 重力效应导致水从冰盖迁移，最终导致 LSL 下降。因为因素 1 往往比因素 2 占主导地位，并且两种影响的幅度随着与冰载荷的距离而下降，最终结果是冰期 LSL 上升在外围隆起的下沉外侧向南下降（即横断面 2-4 [T2-4]）。此外，由于 T3 的纬度使趋势趋于平缓，因此 T3-4 的 LSL 预测显示变异性降低（图 1C）。T1 最大程度位于靠近冰荷载的边缘，LSL 大幅下降与引力效应相关，再加上冰消期更温和的地壳位移，最终导致相对于 T2-4 的 LSL 变化不大。T1 与冰荷载的接近在预测的海平面信号中引入了大的海岸垂直梯度（图 S1A）。相比之下，尽管海洋载荷效应（Nakada 和 Lambeck，1989；Mitrovica 和 Milne，2003）可能促成了这些梯度（图 S1B- S1D)。图 3 说明了从 MIS 11 与当今 LSL 历史与一个随机但具有代表性的沉积历史的配对产生的序列地层和岩石地层结构的选择。从每个深度站点库 (n = 50) 中，对单个样带内合成地层柱的比较表明，随着水深适应向盆地的下倾增加，总体地层厚度、保存的 GSS 数量（图 3A 和 3B）以及海退系统域内的水深变化（图 3C 和 3D）也是如此。中深度（100-200 米）的比较）横断面（沿沉积走向）之间的合成地层柱暴露了这些因素的显着差异，具有一致的地理格局（图3A和3D）。例如，T1 始终保留具有最高 GSS 计数的最长柱（例如，130 m 深度的四个序列），其在 T2 处收缩为两个序列，并再次向 T3-4 扩展至大约三个序列（图 3A） . 对于所有沉积情景，对于 130-200 m 深度的站点，横断面之间的 GSS 平均计数差异最高且具有统计学意义（p < 0.05）（图 3B；表 S1）。相似地，在横断面之间，GSS内水深的明显变化变化很大（图3C）；例如，T2 记录了 200 m 及更深的地点进入末次盛冰期（LGM）低位的最大局部水深变化，因此，冰量增长的最大表观幅度（图 3C 和 3D；表 S2） ）。然而，冰川周期的数量和幅度的这些地理模式不适用于 1-50 m 和 250 m 深度的站点，因为这些柱在统计上更相似（图 3B 和 3C），由于相对于 LSL 变化的幅度，分别是有限和无限的测深适应（图 1C）。图 4 显示了在选定深度地点的局部 MIS 2（LGM）低水位 SU 或 CC 顶部保存的海侵沉积年份的实际年龄分布. 模型运行显示高达 5 ky，或最近的冰期间冰期循环的 1/24，随着海平面上升到达逐渐变浅的深度地点，上倾穿时性（图 4，深度地点的颜色分布相同）。跨货架穿时性更为明显（图 4，同一深度站点的不同颜色分布）。例如，在 130 m 深度的站点中，T4 的局部海侵恢复了约 8 ky，或周期的 1/15，早于 T1（分别为 16.89 ka ± 4.41 ky [1σ] 与 8.95 ka ± 7 ky） . 无论 MIS 10、8 和 6 海侵表面存在历时性，给定表面的局部表达可能在 T1 早期出现高达 ~150 ky 或 >1 个周期（图 S2）。如果冰川是一个全球信号，构造和沉积在任何地方都是相同的，那么在相同测深深度的横断面之间的地层柱将无法区分，并保留有关海平面和冰量变化的相同信息。相反，大陆架上的中等深度站点显示出最大的相互偏离。这直接反映了 GIA 对由该正向模型产生的冰期-间冰期地层旋回的保存和特征的贡献。最接近冰的中间地点 T1 深度为 130 m 的地层记录库始终保存着冰川周期的最高数量，冰川消退的最早年龄（LGM除外），并且正如LSL曲线（图1C）所预期的那样，LSL变化的最小幅度。相比之下，T2 在 130 m 深度，位于外围凸起的外侧，记录了最少数量的冰川周期，并且导致 LGM 的 LSL 变化的幅度被侵蚀所掩盖（图 3C 和 3D）。中深度站点更好地揭示了岩相响应 GIA 引起的单个样带 LSL 变化的回生和进积。然而，即使在整个海岸线的沉积和构造保持相同时，GIA 也会导致横断面之间的位置保持不同数量的冰期-间冰期旋回、LSL 低水位的表观大小以及地层中 SU/CC 后保留的海侵沉积年龄这些模型实验表明，GIA 可以使 102-103 公里距离（T1-T2）和更远距离（T3-T4；图 3A 和 3D）的大陆架地层记录的沿走向相关性复杂化。根据保存的田野边缘相对于同期冰缘，地层学家可能会得出关于同一冰期的相互矛盾的信息。GIA 通过冰期-间冰期循环产生地理上可变的 LSL 变化。在这项研究中，我们展示了 GIA 引起的 LSL 和适应变化如何改变大陆架地层记录中冰期间冰期 GSS 的保存。当构造、沉积和测深深度相同时，横断面之间的合成地层柱显示有关冰量变化的数量、幅度和时间的不同信息。因此，大陆架合成地层柱在几个冰川振荡中的准确相关性在靠近前冰盖（T1）的地点和外围凸起外侧的地点之间是最困难的，尽管最接近凸起顶部（T2）。在外围凸起（T3 和 T4）外侧更远的部分向南趋势的柱子的准确关联更容易。观察到这种模式的测深深度范围将根据初始测深、沉积物积累速率和 LSL 历史而变化。对大陆地层记录中 GIA 信号的更好理解可以改进从该物理档案中推断出的冰川数量、规模和年龄的重建。这项研究由美国促成 美国国家科学基金会奖 2046244，美国地质学会 (GSA) 研究生研究资助，以及俄勒冈州立大学乔治和丹妮尔夏普奖学金。我们感谢 JX Mitrovica 的 LSL 历史和深思熟虑的讨论，以及 Steven Holland 和两位匿名审稿人，他们的评论改进了本文。