Global sea-level changes and substantial vertical displacement along the Monte Grande Fault (MGF) in the lower Río Ica Valley of south-central Peru influenced the accumulation of bioclast-bearing and diatom-bearing Miocene siliciclastic sediments in an area of the East Pisco forearc basin (EPB) colloquially known as Laberinto. Two depositional hiatuses in the Laberinto area (~17–14 Ma, ~12.5–10 Ma) manifest as sediment-filled erosional depressions a few kilometers in breadth. Erosion of the older depression was preceded by an ~18-Ma massive debris flow, possibly triggered by motion on the MGF causing lower Miocene lithoclastic olistoliths of up to two hundred meters length to spill off the footwall block. Sediment shed from the same footwall block may have formed previously recognized early Miocene deltas. From 14 to 13 Ma, the older depression filled with sediments herein assigned to the provisionally named Laberinto, Pampa, and Naranja members of the Pisco Formation, the latter member being characterized by marine delta foreset beds. The three members are at least partly correlative with the Pisco-0 sequence of the Pisco Formation. The younger depression was overrun at 10 Ma by debris flows of lithoclastic and granitic cobbles and boulders, then filled with diatomaceous silty sand with 5-m-sized lithoclastic olistoliths. The two lithologies constitute the provisionally named Mature Formation. Radiometric and newly revised biochronological data from throughout the EPB coupled with new diatom data from the Laberinto area have provided new insights into the correlation of sequences within the Chilcatay and Pisco formations and the interaction of local and basin-wide tectonism and global eustatic sea-level events across the basin.

全球海平面变化和沿秘鲁中南部里奥伊卡河谷下游的蒙特格兰德断层 (MGF) 的大量垂直位移影响了东皮斯科前弧区域含生物碎屑和含硅藻的中新世硅质碎屑沉积物的积累盆地 (EPB) 通俗地称为 Laberinto。Laberinto 地区的两个沉积间断（~17-14 Ma，~12.5-10 Ma）表现为几公里宽的沉积物侵蚀洼地。旧洼地的侵蚀发生在大约 18 Ma 的大规模碎屑流之前，这可能是由 MGF 上的运动引发的，导致下中新世长达 200 米的碎屑石碎石从下盘块体溢出。来自同一下盘地块的沉积物可能形成了先前公认的早中新世三角洲。从 14 到 13 马，充满沉积物的较老洼地被指定为暂时命名为 Pisco 组的 Laberinto、Pampa 和 Naranja 组，后者的特征是海相三角洲前床。这三个成员至少部分与 Pisco 地层的 Pisco-0 层序相关。年轻的凹陷在 10 Ma 被碎屑岩和花岗石鹅卵石和巨石的碎屑流淹没，然后充满硅藻质粉砂和 5 米大小的碎屑石碎石。这两种岩性构成了临时命名的成熟地层。