Geochemistry of basement clasts from sediment core CRP-3 in the ross Sea, Antarctica

Distribution patterns and petrographical and mineral chemistry data are described for the most representative basement lithologies occuring as clast in the c. 824 m thick Tertiary sedimentary sequence at the CRP-3 drillsite. These are granule to bolder grain size clasts of igneous and metamorphic rocks. Within the basement clast assemblage, granitoid pebbles are the predominant lithology. They consist of dominant grey biotic-bearing monzogranite, pink biotite-hornblende monzogranite, and biotite-bearing leucomomonzgranite. Minor lithologies include: actinolite-bearing leucotonalite, microgranite, biotite-hornblende quartz-monzonitic porphyr, and foliated biotic leucomonzogranite. Metamorphic clasts include rocks of both granitic and sedimentary derivation. They include mylonitic biotic orthogneiss, with or without garnet, muscovite-bearing quartzite, sillimanite-biotite paragneiss, biotite meta-sandstone, biotite-spotted schist, biotite-clacite-clinoamphibole meta-feldspathic arenite, biotite-calcite-clinozoisite meta-siltstone, biotite±clinoamphibole meta-marl, and graphite-bearing marble. As in previous CRP drillcores, the ubiquitous occurence of biotite±hornblende monzogranite pebbles is indicative of a local provenance, closely mirroring the dominance of these lithologies in the on-shore basement, where the Cambro-Ordovician Granite Harbour Intrusive Complex forms the most extensively exposed rock unit.

本数据集描述了CRP-3钻探位点（CRP-3 drillsite）处厚约824米的第三纪（Tertiary）沉积序列中，以碎屑（clast）形式产出的典型基底岩性的分布模式、岩石学（petrographical）及矿物化学数据。该类碎屑的粒径范围为砾石级至巨砾级，涵盖火成岩（igneous rock）与变质岩（metamorphic rock）两类。
在基底碎屑组合中，花岗质岩砾石（granitoid pebble）为优势岩性，主要由三类岩石组成：含黑云母（biotite）的灰色二长花岗岩（monzogranite）、含黑云母-角闪石（hornblende）的粉色二长花岗岩，以及含黑云母的淡色二长花岗岩（leucomonzogranite）。次要岩性包括含阳起石（actinolite）的淡色英云闪长岩（leucotonalite）、细晶花岗岩（microgranite）、含黑云母-角闪石的石英二长斑岩（quartz-monzonitic porphyry），以及具片理（foliated）的含黑云母淡色二长花岗岩。
变质岩碎屑涵盖花岗质源与沉积质源两类岩石，具体包括：含或不含石榴子石（garnet）的糜棱岩化（mylonitic）含黑云母正片麻岩（orthogneiss）、含白云母（muscovite）石英岩（quartzite）、矽线石（sillimanite）-黑云母副片麻岩（paragneiss）、黑云母变质砂岩（meta-sandstone）、黑云母斑点片岩（spotted schist）、黑云母-方解石（calcite）-斜角闪石（clinoamphibole）变质长英质砂屑岩（feldspathic arenite）、黑云母-方解石-斜黝帘石（clinozoisite）变质粉砂岩（meta-siltstone）、含黑云母±斜角闪石变质泥灰岩（meta-marl），以及含石墨大理岩（marble）。
与此前的CRP钻探岩芯一致，含黑云母±角闪石的二长花岗岩砾石的普遍产出特征指示其为本地物源区（provenance），这与陆上基底中此类岩性的占比高度吻合——寒武-奥陶纪格兰德港侵入杂岩（Granite Harbour Intrusive Complex）是陆上基底中出露最广泛的岩石单元。