ESH: Development of Luminescene Banding in Speleothems as a High Resolution Climatic Record

9809138白色以前的研究表明，腐殖物质，主要是富里酸，纳入次生方解石晶体的洞穴洞穴沉积物产生一个明显的发光带。 这些条带在圆柱形石笋的纵剖面和从平面流石沉积物中切下的芯或板中观察得最清楚。 这些条带的宽度在10 - 100微米的数量级上，似乎代表了每年的干湿循环，其中每个条带代表了石笋一年的生长。 在条带内有许多额外的细节。 一个1米高的石笋可能含有代表20,000年沉积的条带。 因此，发光带，是一个非常高的分辨率的气候记录的潜力。本建议的目的是建立一个健全的基础，古气候解释的发光带在洞穴沉积物。 有三个主要目标。(i)构建一个仪器，将测量激光激发发光强度沿着的洞穴沉积物的纵向截面与高光度精度，空间分辨率为几微米，和跟踪的空间位置在几微米。 这是通过使用现有的微焦点拉曼光谱仪作为基础仪器，并构建一个计算机控制的机械平台来平移石笋板来实现的。(ii)进行一系列广泛的测量，相互比较从同一标本的多个断面获得的记录，从同一洞穴内同一地点收集的标本，以及从一个小地理区域内的洞穴收集的标本。 需要这些测量来建立发光带记录的再现性，并测试方法来匹配重叠但不相同年龄的洞穴沉积物的记录。(iii)为最近的洞穴沉积物生长构造发光带剖面图，与当代气候记录进行比较。 这是一个校准步骤，将发光强度的特定变化与历史记录中的已知降水和其他气候事件相关联。(iv)构建跨越晚全新世洞穴沉积物的剖面图，以便将发光带的细节与其他近期古气候记录进行比较。(v)如果项目（i - iv）按计划进行，该项目将为更广泛地研究更早的洞穴记录奠定基础，该记录可追溯到更新世。

9809138WhitePrevious research has shown that humic substances, mainly fulvic acid, incorporated into the secondary calcite crystals of cave speleothems produce a distinct luminescence banding. The bands are best observed in longitudinal sections of cylindrical stalagmites and in cores or slabs cut from planar flowstone deposits. The bands have widths on the order of 10 - 100 micrometers and appear to represent annual wet and dry cycles where each band represents one year's growth of the stalagmite. There is much additional detail within the banding. A 1-meter high stalagmite might contain bands representing 20,000 years of deposition. The luminescence bands, therefore, have the potential for being a very high resolution climatic record.The intent of this proposal is to establish a sound basis for the paleoclimatic interpretation of the luminescence banding in speleothems. There are three main objectives.(i) Construct an apparatus that will measure laser excited luminescence intensity along longitudinal sections of speleothems with high photometric accuracy, spatial resolution of a few micrometers, and tracking of spatial position within a few micrometers. This is to be accomplished by using an existing microfocus Raman spectrometer as a base instrument and constructing a computer controlled mechanical stage to translate the slab of stalagmite.(ii) Conduct an extensive series of measurements intercomparing the records obtained from multiple transects of the same specimen, specimens collected from the same location within the same cave, and specimens collected from caves within a small geographic area. These measurements are needed to establish the reproducibility of luminescence banding records and to test methods for matching the records for speleothems of overlapping but not identical ages.(iii) Construct luminescence-banding profiles for very recent speleothem growth to compare with contemporary climatic records. This is a calibration step to correlate specific variations in luminescence intensity with known precipitation and other climatic events in the historical record.(iv) Construct profiles spanning late Holocene speleothems so that the details of luminescence banding may be compared with other recent paleoclimatic records.(v) If items (i - iv) work out as planned, this project would lay the groundwork for a more extensive study of speleothem records extending farther back into the Pleistocene.