济南市历下区龙洞地区新近纪上新世一第四纪更新世白彦组地质特征

残存于济南市历下区龙洞一带下古生界出露区岩溶负地形中的砾岩体，总体呈浅褐灰色，由砾石及胶结物组成。灰岩、白云岩砾石，砾径大小不一，呈次棱角一次圆状，燧石砾、褐铁矿砾成熟度高、磨圆度好，表面光洁，呈蜡状光泽，钙质孔隙式及接触式胶结，已硬结成岩，砾岩体与周围呈角度不整合接触关系。通过对比研究，初步认定其为新近纪上新世一第四纪更新世白彦组沉积，这一新发现填补了该区岩石地层单位的一项空白，为研究地质构造发展史提供了重要的佐证。

Geological Characteristics of Neogene Baiyan Group in Longdong Area in Lixia District of Jinan City

Conglomerate ore bodies exposed in lower Paleozoic karst terrain residued in Longdong area in Lixia district of Jinan city are overall pale brown - gray. They are composed of gravel and cement. Diame- ter sizes of limestone and dolomite gravels are different. They are sub - angular and sub - rounded types. Flint gravels and limonite gravels have high maturity and good roundness. Their smooth surfaces are waxy luster with calcium pore type and contact cement. Conglomerate has an angular unconformity contact rela- tionship with the surrounding areas. By contrast and study, it is primarily determined that it is Neogene Baiyan group deposition. This new discovery can fill the blank of lithostratigraphic units in this area. It wll provide important evidences for studying the history of geological structures.