Xinjiang Petroleum Geology ›› 2025, Vol. 46 ›› Issue (5): 637-646.doi: 10.7657/XJPG20250515

• OIL AND GAS GEOLOGY ABROAD • Previous Articles    

Evaluation of Paleoweathering Characteristics of Igneous Rock Basements

LIANG Fei(), NIU Jun(), HE Jin   

  1. School of Petroleum, Karamay Campus, China University of Petroleum (Beijing), Karamay, Xinjiang 834000, China
  • Received:2025-03-11 Revised:2025-05-17 Online:2025-10-01 Published:2025-09-30

Abstract:

Paleoweathering crusts are of significant importance for understanding the interactions between the lithosphere and the atmosphere, as well as the rock-water reactions within weathering profiles during burial diagenesis process. This study systematically analyzed petrological, mineralogical, and geochemical characteristics of various igneous rock basements, including gabbro-diorite (GA1 basement), basaltic andesite (GA1 effusive rock interval), quartz diorite (TB8 basement), and granite (BK2/05 basement). The mobility offsets of easily migrating elements such as K, Ca, and Na were quantified using the degree of migration, and the results were cross-referenced with mineral quantitative analysis data from whole-rock X-ray diffraction (XRD) and the petrological features to clarify the burial diagenetic characteristics of the paleoweathering crust in the study area. Subsequently, based on the mineral and element contents, a quantitative correction was applied to Ca content, followed by a correction for K content. The corrected results displayed a well-defined weathering trend in the A-C-K triangular chart, validating the methodology for correction. Using the corrected parameters, the chemical index of alteration (CIA) was employed to quantify the degree of chemical weathering. Additionally, corrections for the original weathering products were performed by integrating protolith characteristics and paleoclimate features, revealing the original weathering characteristics of the paleoweathering profile. Finally, after normalization using weathering indices, the corrected weathering characteristics of each profile exhibited strong correlations with the climatic evolution trends during the Early to Middle Permian.

Key words: southwestern Germany, igneous rock, chemical weathering, paleoweathering characteristic, diagenetic fluid, evaluation method

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